EEVblog Electronics Community Forum

Electronics => Metrology => Topic started by: TiN on September 16, 2015, 08:30:29 am

Title: Repair worklog : Old rusty HP 3458A
Post by: TiN on September 16, 2015, 08:30:29 am
Received final item for volt-nut freaks - 3458A. It's old unit with chassis corrosion from seller in Philippines, which we already discussed in Buy/Sell section here..

So far initial inspection:

* U100 processor MC68HC000P8 had paper sticker BAD (A5 board manufactured 1990)
* Missing button cap on power switch, guard switch and front/rear switch.
* Missing fuse binding post for amps on front panel
* Rust on steel chassis
* Mark "X" on mains power transformer
* Mark "X" on analog board 66501 (manufactured 1996)
* Error message RAM 1 LOW
* Missing voltage reference board (so calibration is meaningless, even if it's still intact in 1990 year DS1220)..
* Missing fuse holder for mains
* Damaged plastic rear panel
* No legs

Smell like lots of work, lots of debug folks.
Title: Re: Repair : Old rusty HP 3458A
Post by: krivx on September 16, 2015, 08:46:53 am
What's the plan? DIY or OEM voltage reference assembly? Will you get this functioning and then refinish/repair the enclosure?
Title: Re: Repair : Old rusty HP 3458A
Post by: Vgkid on September 16, 2015, 08:57:40 am
This will be interesting...
Following.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 16, 2015, 09:46:28 am
Looking forward to this  :popcorn:
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 16, 2015, 12:01:21 pm
Ok, back home with unit now. Let's see what we are dealing with..

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/face_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/face.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bottom_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bottom.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/side_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/side.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/back_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/back.jpg)

Steel chassis is rusty on rear side. Not nice treatment for such an instrument. :(

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/open_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/open.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/rusty_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/rusty.jpg)

Removing covers...

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/dirty_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/dirty.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/dca_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/dca.jpg)

All analog stuff is contained in aluminum box, isolated from steel frame by plastic inserts. HP calls those boards inside as "inguard", rest boards are "outguard".

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/open1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/open1.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/open2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/open2.jpg)

View on both sides without covers. As we can see, no A9 voltage reference present  |O

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/top_open_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/top_open.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bot_open_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bot_open.jpg)

Inguard PSU. Some PCB damage around CR12 visible.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/ingrd_psu_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/ingrd_psu_bot.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/ingrd_psu_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/ingrd_psu_top.jpg)

Outguard primary PSU. All seems ok.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/outg_psu_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/outg_psu_bot.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/outg_psu_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/outg_psu_top.jpg)

68000 CPU, RAM, ROM and digital logic, board A5. Dated 1990, while rest of analog PCBs dated 1996.
Probably seller changed digital PCB afterwards?

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_bot.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_top.jpg)

Removing inguard PSU for now, adding jumpwire instead of fuse (don't have suitable cap), turning on...

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/digital_only_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/digital_only.jpg)

Aha. Nice and bright VFD, which is cool. Now will remove Dallas NVRAMs , and solder sockets instead, so we can troubleshoot this RAM 1 LOW.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 16, 2015, 01:29:30 pm
Removed DS1235Y's, installed collect sockets.
Installed DS1230Y into RAM LOW, now getting message RAM TEST 1 HIGH, which is a good sign.

I don't have any more DS1230Y's, only 1245's :(
Need to order some ebay DS1230Y's and 1220 as well :)
Title: Re: Repair : Old rusty HP 3458A
Post by: free_electron on September 16, 2015, 02:54:53 pm
before you go on power cycling this thing (and cause more damage.)

take it completely apart and wash the digital boards first in a mixture of 50% distilled water and 50% pure alcohol (ipa). let soak for a while .
then wash in pure alcohol ( to displace water )

do NOT blow on the boards to assist evaporating the alcohol ! evaporation cools down so it pulls moisture out of the air that then condensates ...
use a hairdryer set to a low temperature to avoid this from happening.

meanwhile : sandblast the chassis to get the rust off.

it looks to me like these machines have been in a 'flood'. during a topical storm some building flooded and these have been dipped ...

as for the precision analog sections : don;t wash those yet. inspect very carefully under a microscope to detect any residual water stains. if none can be found : leave alone. if you find water stains: wash them.

Title: Re: Repair : Old rusty HP 3458A
Post by: jlmoon on September 16, 2015, 03:14:36 pm
 :-+ +1 to FreeElectron.  Very good advice!!!
Title: Re: Repair : Old rusty HP 3458A
Post by: MadTux on September 16, 2015, 05:40:52 pm
Boards are looking better than I expected. So not everything is lost yet.

I would contact the seller and ask him to give you a reference board for free, since it wasn't mentioned as missing.

Apart from sand blasting, you can also treat the rusted steel parts with dilute phosphoric acid. It will convert the iron oxide to a thin, transparent, insoluble iron(III)phosphate layer that will also act as a rust protection layer, similar to the aluminum oxide layer on aluminum parts. https://en.wikipedia.org/wiki/Iron%28III%29_phosphate

Badly rusted stuff is best cleaned by cathodic electrolysis (use the part to be cleaned as negative electrode) together with a non corrosive electrolyte (e.g. sodium carbonate, beware of any halide salts, since they will corrode stuff like crazy after treatment). The hydrogen that gets generated on the cathode will flake away larger oxide particles while protectig the remaining non corroded metal from further attack.

Don't use it for too long however, because the (monoatomic) hydrogen might eventually lead to hydrogen embrittlement

Good luck
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 16, 2015, 06:44:00 pm
Thanks for advices.
Only boards powered currently are A5, outguard supply and front panel.

Already checked most analog boards, it does not look like anything was flooded at all, not even dust on PCBs.
So I don't touch analog stuff just yet.

First step would be fixing digital side (ordered memories already), and checking power supplies (transformer, outguard, inguard).
Two zeners on inguard PSU (CR11,CR12) are shorted, so need replace those too.

Transformer output to inguard seems real fishy, secondary resistances <0.5ohm (5-pin connector P1) and output only 7VAC.  :-BROKE
Title: Re: Repair : Old rusty HP 3458A
Post by: free_electron on September 16, 2015, 07:05:05 pm
i'd still clean those boards first. the problem is we dnot know what the machine was submerged in.. freshwater ? saltwater ? what is the salts content ? any salt deposit combined with humidity is a disaster waiting to happen. dendrite growth... one dendrite and it's game over for this beuatiful machine

that's why the 50/50 mix of distilled water and alcohol. alcohol cannot dissolve salts. water does.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 16, 2015, 07:54:11 pm
It does look like the seller gathered together all the worst boards from his other 3458's and shoved them into a single unit. I don't mean he diagnosed them as faulty but looked at the labels someone previously diagnosed and marked and pulled out those boards and put together a whole unit, then assumed all the boards and transformers not marked bad were good and parted them out to sell seperately? (and the good VREF too)

The swine!  :palm:

Of course it is still repairable and the MCU is working and the VFD looks nice. The other unit on ebay looks in worse condition.

But definitely clean at least the digital and power boards with IPA and distilled water, and of course don't even put a fingerprint (or voltage) on the analogue boards yet!

But what do I know? I think I'm teaching a grandma to suck eggs here!  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 16, 2015, 07:59:46 pm
I actually quite surprise how clean the boards are, would have expected much more corrosion on those boards. Reason why I didn't make a offer and take it. Plus I had bad luck with that seller. Let just say signal generator I bought from them was suppose to be working and was missing parts and in worst condition then expected. To make matters worst someone was inside it strip most the screws, hook DC fan to AC fan port and mark the power supply board a XX, so they knew it was defective, even manage to hook the LCD front panel backwards, so it would have never work in it's condition. Don't get how they figure in working condition?. The only reason didn't leave a Negative, was due to they sent another one out and was able to repair the power supply off the first one, took the good RF board off the second one and case since it had no rust and still in good shape. Rebuilt the RF boards with new Philips modules and make a complete working and back within spec. Replaced all out of spec capacitors. Cost some money and time, won't buy from them again. Just wondering what they do over there in the Philippines? Leave this stuff pile outside?



Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on September 16, 2015, 08:03:18 pm
The Keithley 2001 was a restoration of glory, what will this one be? "glory squared" perhaps?

Really looking forward to your progress.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 16, 2015, 08:09:56 pm
Just wondering what they do over there in the Philippines? Leave this stuff pile outside?
Some pretty bad natural disasters / acts-of-god for the heathens daring to copulate for reasons other than procreation, like https://en.wikipedia.org/wiki/Typhoon_Haiyan (https://en.wikipedia.org/wiki/Typhoon_Haiyan)

Faced with that kind of $billions damage, a lot is going to end up scrapped. There are a lot of very very poor people in the Phillipines who make a living literally scavenging the landfill rubbish tips this will have been dumped in. A child will have been given $1 tops for finding this and it has passed through many hands before it ends up with someone who has the nous and capital to flog it on ebay.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 16, 2015, 08:53:02 pm
68000 CPU, RAM, ROM and digital logic, board A5. Dated 1990, while rest of analog PCBs dated 1996.
Probably seller changed digital PCB afterwards?

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_bot.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_top.jpg)


They more likely kept most the good boards and swapped defective ones in and took voltage reference board.
Title: Re: Repair : Old rusty HP 3458A
Post by: MadTux on September 16, 2015, 09:25:55 pm
They more likely kept most the good boards and swapped defective ones in and took voltage reference board.
Defective isn't a problem, since you can change broken chips and or replace them with sockets to have it easier in the future. Only a matter of time, equipment and skill.

But if trace on PCB or vias are corroded away, then the PCB and thereby the instrument is usually done. It's dead Jim, nothing you can do. So I guess TiN was actually quite lucky, since that wasn't exactly clear from low res ebay photos. And I have seen and had far worse PCBs in my hands. Mostly salt water and battery damage that was neglected for years.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 16, 2015, 09:50:56 pm
They more likely kept most the good boards and swapped defective ones in and took voltage reference board.
Defective isn't a problem, since you can change broken chips and or replace them with sockets to have it easier in the future. Only a matter of time, equipment and skill.

But if trace on PCB or vias are corroded away, then the PCB and thereby the instrument is usually done. It's dead Jim, nothing you can do. So I guess TiN was actually quite lucky, since that wasn't exactly clear from low res ebay photos. And I have seen and had far worse PCBs in my hands. Mostly salt water and battery damage that was neglected for years.

True...Shock how clean the PCB's are, would have expected a lot of corrosion damage. Looks like it was left outside, but not flooded. So water stay outside the case pretty much is what I suspect, otherwise damage would have been a lot worst. Have seen and dealt with the worst. Sucks when a battery or capacitors leak everywhere on the board eating away at traces and pads, or other components.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 16, 2015, 11:38:19 pm
To give little more coverage, here are closeup on PCBs, so you  can see condition.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb1.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb2.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb3_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb3.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb4_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb4.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb5_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb5.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb6_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/pcb6.jpg)

Only visible residues are on outguard PSU board. A5 digital board looks much more dusty than any other board, so it's likely was swapped.
Other boards are all within 1995-1996 year, I think they are original.

What worry me a bit, is a transformer. Anybody have good one to measure windings resistance / voltage on P1 connector which goes to inguard PSU?
Not sure if data posted here (http://www.prc68.com/I/HP3458DVM.shtml) is 100% valid.

Also how about firmware? Mine is Rev.6, anyone have Rev.9 dumps for future update?

3458-88860 Rev6 firmware ROM dump (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/fw/REV6/03458-88860.BIN)
3458-88861 Rev6 firmware ROM dump (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/fw/REV6/03458-88861.BIN)
3458-88862 Rev6 firmware ROM dump (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/fw/REV6/03458-88862.BIN)
3458-88863 Rev6 firmware ROM dump (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/fw/REV6/03458-88863.BIN)
3458-88864 Rev6 firmware ROM dump (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/fw/REV6/03458-88864.BIN)
3458-88865 Rev6 firmware ROM dump (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/fw/REV6/03458-88865.BIN)
Title: Re: Repair : Old rusty HP 3458A
Post by: eas on September 17, 2015, 12:16:59 am
Thanks for posting. I'm looking forward to seeing how this progresses.
Title: Re: Repair : Old rusty HP 3458A
Post by: Radio Tech on September 17, 2015, 12:44:04 am
Hope you  get this going and thanks for posting this. :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on September 17, 2015, 03:10:24 am
I can make time tomorrow to measure the transformer windings. I will have to clear the bench to make some room.

Rev 8 or 9 will be pretty much the same functionally. Maybe there is something available  ::)

Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on September 17, 2015, 02:07:17 pm
I have verified that the measurements for the inguard transformer connector are correct. Mine are nearly identical to those posted on the web page. All measurements were made with no load.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on September 17, 2015, 02:20:17 pm
I forgot to mention that the large blue capacitor on the bottom looks like it is turned. I usually have to replace the rotted foam along its edge and I see that yours is rotated away from the cover.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 17, 2015, 03:11:08 pm
Thank you. Then it's safe to confirm that my transformer is busted.
I tried to open it up, but it's all covered in lacquer, and my patience run out quickly.

Front panel must be removed in order to remove mains transformer.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_face_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_face.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_back_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_back.jpg)

Looking good, just minor cleaning required..

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_label_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_label.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/terminal_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/terminal.jpg)

Frontpanel PCBA label and front binding post terminals.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/xfrmr_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/xfrmr.jpg)

Transformer have two winding sections, primary with secondary for outguard +5V rail (goes to digital board and front panel, that's why it's working).

Second section for inguard supply is inner bobin with two secondary windings (one with center tap to generate +18/-18 and second for +5V analog).
This windings in my transformer are shorted together!

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/sch/t1_fail.png)

I would not trust repaired/rewinded transformer in such an instrument anyway, so going to make Agisight richer for $337 to get new transformer.
Title: Re: Repair : Old rusty HP 3458A
Post by: Jwalling on September 17, 2015, 03:14:38 pm
Is that mu metal in the picture with the transformer by any chance?

Jay
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 17, 2015, 03:34:00 pm
Transformer on eBay for $199 with matching part #. Would message them, to see if they will accept lower, worth a shot.

http://www.ebay.com/itm/HP-Agilent-3458A-9100-4715-Transformer-Power-/281271495323?hash=item417d166a9b (http://www.ebay.com/itm/HP-Agilent-3458A-9100-4715-Transformer-Power-/281271495323?hash=item417d166a9b)
Title: Re: Repair : Old rusty HP 3458A
Post by: klaus11 on September 17, 2015, 08:36:51 pm
8.5 digit calibration costs only 1500 USD  :scared:, It will be nice to see it work
Title: Re: Repair : Old rusty HP 3458A
Post by: BFX on September 17, 2015, 11:33:55 pm
TiN: nice unit and good luck to repair :-+ I love your repair threads  8)

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 18, 2015, 12:40:42 am
Transformer on eBay for $199 with matching part #. Would message them, to see if they will accept lower, worth a shot.

http://www.ebay.com/itm/HP-Agilent-3458A-9100-4715-Transformer-Power-/281271495323?hash=item417d166a9b (http://www.ebay.com/itm/HP-Agilent-3458A-9100-4715-Transformer-Power-/281271495323?hash=item417d166a9b)
I would prefer not to risk of used xfrmr. Will stick to new one from Keysight, as still need some other parts, like pusrods, caps, feet , etc.
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on September 18, 2015, 12:44:04 pm
Transformer on eBay for $199 with matching part #. Would message them, to see if they will accept lower, worth a shot.

http://www.ebay.com/itm/HP-Agilent-3458A-9100-4715-Transformer-Power-/281271495323?hash=item417d166a9b (http://www.ebay.com/itm/HP-Agilent-3458A-9100-4715-Transformer-Power-/281271495323?hash=item417d166a9b)
I would prefer not to risk of used xfrmr. Will stick to new one from Keysight, as still need some other parts, like pusrods, caps, feet , etc.

Just curios because You don't have the reference board. Are You plan to build your own or buy a new one ?
honestly I want to see You build the reference board with "your magic solder"  :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 18, 2015, 03:12:13 pm
Bought one from ebay already. :)

Title: Re: Repair : Old rusty HP 3458A
Post by: Smith on September 18, 2015, 06:57:47 pm
Just played around with an original HP one today. Verry impressive machine! I really like the keys and the display. Not exactly the most user friendly interface though, and all the six red binding posts wheren't verry helpful either.
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on September 20, 2015, 11:33:37 am
Bought one from ebay already. :)

What I hates about buy a meteorology meter like this is the cost of calibration, agilent ask about USD 2800 for golden calibration include Shipping and handling> ( I am in Indonesia and the calibration must be done in Singapore)  |O
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 20, 2015, 02:25:48 pm
Bought one from ebay already. :)

What I hates about buy a meteorology meter like this is the cost of calibration, agilent ask about USD 2800 for golden calibration include Shipping and handling> ( I am in Indonesia and the calibration must be done in Singapore)  |O

Short of access to a josephson junction array I think TiN has enough gear to do a pretty good cal all by himself. Indeed - maybe Project KX will be ready in time?  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on September 20, 2015, 08:39:22 pm

What I hates about buy a meteorology meter like this is the cost of calibration, agilent ask about USD 2800 for golden calibration include Shipping and handling> ( I am in Indonesia and the calibration must be done in Singapore)  |O

Sorry, it's metrology.
The other one's about the weather..
Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on September 20, 2015, 08:41:56 pm

Short of access to a josephson junction array I think TiN has enough gear to do a pretty good cal all by himself. Indeed - maybe Project KX will be ready in time?  ;)

Nope.
All of his Keithleys are playin' in a minor league.

You need 10V and 10kOhm and means for verification on sub ppm level.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 21, 2015, 04:39:43 am
Ended up just winning a HP 3458A, same seller. Hopefully I actually get the reference board.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 21, 2015, 07:06:15 am
Ended up just winning a HP 3458A, same seller. Hopefully I actually get the reference board.
Blimey, for that price I hope you get the ref board too! Keep us all posted on your restoration!  :-+

When repaired it looks like getting them calibrated will be interesting... (I mean DIY rather than sending them to Key$ight)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 21, 2015, 10:57:25 am
Mm, "DIY" calibration of 8.5 gear is somewhat mythical. My personal plan on this is:

A. Clean all dirt, replace broken parts (so far transformer, pair of protection zeners in inguard PSU, dead NVRAM, missing knobs+levers)
B. Install missing LTZ1000 reference (already one of those ebay units on its way).
C. Carefully test and repair analog section (if needed). This item is a real deal, and if unobtanium stuff dead - can quickly make whole project worthless.
D. If all analog stuff works - assembly meter and ACAL it to my K2002 readings on 10v and 10k. This will let me check overall function, drift, noise and such.
E. In some distant future , if everything works really well - send it to Keysight for cal.

OldSchoolTechCorner

Ouch, 1.1k? Kinda steep to my liking, hope you know what to expect. Photos clearly show missing ref board. But its not the reference you should worry about (they are up for sale for little over 100$ like cakes on ebay now) but that paper sticker "Defective" on transformer. You looking at 337$ replacement if u choose to get new from HP.

I would not mind at all if you post you progress in this very same thread, as its same topic, same seller, same stripped parts!
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on September 21, 2015, 11:18:24 am

E. In some distant future , if everything works really well - send it to Keysight for cal.


I propose to exchange 7.14V ... 10V LTZ reference(s) and 10KOhm (Vishay) with some other volt-nuts, instead.
Maybe a ww. ring comparison.

PS: Ah yes, after the 10V /10k calibration relative to your 2002, the complete verification of all ranges of your 3458A against your 2002 is important, to check, if everything is ok.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 21, 2015, 11:22:41 am
Ring comparison across multiple voltnuts around the globe is interesting but it need to be planned and executed well. It should be properly designed box for that kinda thing.

And it does not help with AC ranges, as 3458A still needs external cal for that, if I understood manual correctly.

Testing every function on every range is my plan, yes.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 21, 2015, 11:41:57 am
Ring comparison across multiple voltnuts around the globe is interesting but it need to be planned and executed well. It should be properly designed box for that kinda thing.
Yes, that is the sort of thing I meant as a DIY vs Key$ight cal. Of course if you want to sell the restored meter on then a proper traceable cal will be worthwhile, but then I've read it costs $2800!!! I've also read that if the whole provenance on the meter including repairs is not carried out by Keysight then they will not issue a cal for it?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 21, 2015, 02:45:10 pm
Btw, in case someone got FALSE impression that buying dead 3458A and fixing it would be cheap, here are expenses on my unit so far:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/parts_initial.png).

Add calibration (let's say $2660), and you looking into healthy 4.4K$, for which you can get working and likely even calibrated 3458A from second-market.
Also you can see I cut few corners here and there with parts from eBay, as if you go with all original parts from Keysight, it will be much more (Reference board alone is 700$).

Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 21, 2015, 03:39:29 pm
These are far from being cheap to be repaired. My first keithley 2015 I did a while ago, spend about $400 in parts alone, not including sending it off for calibration and then the long lead times to wait for the parts. Still was worth it, as looks like new now and works great, wish I did a video of that one, that was before really was into doing video restorations.

Just bought another one be working on soon, just to do a new line of videos of test gear repairs and teardown, as videos before were of reel to reels and audio gear restorations. The HP going to be a very interesting project. Use to big restorations like this, even good at getting of rust and corrosion making frame and chassis look like new. Just have to see condition of PCB boards and components, hopefully not corroded, as has it way of working it way into the package destroying the components. This didn't look as bad, but will soon find out. 

Next project going to be getting a new larger work bench put together and the second keithley 2015 first done, since I order most the parts already, did order the kit to convert rack mount to bench meter and quite a few other parts. Will do a complete teardown, repair and rebuilt. The good news is VFD is nice and bright and has newer firmware. The HP will be later on, has have to study service manual some more while waiting for it to arrive and then will see what it needs and what broken and start pricing out parts. Transformer will more likely need to be replace, just going to buy a new one from Keysight, rather then fuss with trying to rewind it. Have to see what other issues it has first and overall condition. On the HP figured I have to put another $700 to 1k into it in parts before calibration.

(http://i1220.photobucket.com/albums/dd456/retropcdos/20150921_102441_zpsicnr31yp.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20150921_102441_zpsicnr31yp.jpg.html)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 21, 2015, 03:43:43 pm
Cool. From KI stuff I have just two 2001's and 2000 waiting to finish up repairs. I usually don't bother with exterior parts , unless they really busted or/and affect functionality.
Title: Re: Repair : Old rusty HP 3458A
Post by: macboy on September 21, 2015, 04:38:57 pm
Btw, in case someone got FALSE impression that buying dead 3458A and fixing it would be cheap, here are expenses on my unit so far:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/parts_initial.png).

Add calibration (let's say $2660), and you looking into healthy 4.4K$, for which you can get working and likely even calibrated 3458A from second-market.
Also you can see I cut few corners here and there with parts from eBay, as if you go with all original parts from Keysight, it will be much more (Reference board alone is 700$).

Keysight's one-time repair is $ 2823 USD. This includes post-repair calibration and adjustment.
For that fixed price they will completely restore the unit to factory spec. I have even heard of users getting new front panels, with updated company name (your old HP 3458A becomes a Keysight 3458A). Of course the unit would need to be complete, so you'd need to install a ref board first.
It sounds like a lot, but you do not know where the end of the cost is for your at home repair, or even if it will ever work after all that expense.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 21, 2015, 04:58:20 pm
Btw, in case someone got FALSE impression that buying dead 3458A and fixing it would be cheap, here are expenses on my unit so far:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/parts_initial.png).

Add calibration (let's say $2660), and you looking into healthy 4.4K$, for which you can get working and likely even calibrated 3458A from second-market.
Also you can see I cut few corners here and there with parts from eBay, as if you go with all original parts from Keysight, it will be much more (Reference board alone is 700$).

Keysight's one-time repair is $ 2823 USD. This includes post-repair calibration and adjustment.
For that fixed price they will completely restore the unit to factory spec. I have even heard of users getting new front panels, with updated company name (your old HP 3458A becomes a Keysight 3458A). Of course the unit would need to be complete, so you'd need to install a ref board first.
It sounds like a lot, but you do not know where the end of the cost is for your at home repair, or even if it will ever work after all that expense.

That reasonable, may go that route and get the reference board of eBay, as much cheaper for the HP and still be under the 5k mark. Have to get it and see shape and missing parts first and then make a few phone calls.
Title: Re: Repair : Old rusty HP 3458A
Post by: macboy on September 21, 2015, 05:30:33 pm
Keysight's one-time repair is $ 2823 USD. This includes post-repair calibration and adjustment.
For that fixed price they will completely restore the unit to factory spec. I have even heard of users getting new front panels, with updated company name (your old HP 3458A becomes a Keysight 3458A). Of course the unit would need to be complete, so you'd need to install a ref board first.
It sounds like a lot, but you do not know where the end of the cost is for your at home repair, or even if it will ever work after all that expense.

That reasonable, may go that route and get the main parts like transformer and reference board on the HP and still be under the 5k mark. Have to get it and see shape and missing parts first and then make a few phone calls.
You should verify whether calibration is indeed included. Their description of their repair services says calibration/adjustment is included, but they doesn't specifically mention it for this service (it might be an exception or simply an omission). Personally I would have a hard time believing that they would return the instrument in working condition but utterly unable to take meaningful measurements.
Title: Re: Repair : Old rusty HP 3458A
Post by: MadTux on September 21, 2015, 06:58:49 pm
Interesting compilation or repair costs.

Somewhat confirms my theory that hardcore repair of (old) equipment like this 3458A is only economic if you can score several units really cheap and sacrifice one or two units to repair the rest. Or if you know the equipment well enough to be sure that the fault is certainly repairable (like the majority of "dead" 3456A where you only need to change PSU caps) . As soon as you start buying parts from ebay or even from OEM, you are usually loosing money.

If you are too cheap to buy parts (like me) than you end up with a pile of working gear and another pile that has some broken unobtanium inside that is waiting for a cheap, broken parts transplant unit from ebay.
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on September 21, 2015, 07:35:24 pm
Yepp, I fully agree.
Buying potential damaged tools is like playing in a lottery. Sometimes you are lucky and sometimes you don't.
If the repair is not just fun it it self (like I love to dig into old analogue circuits) and more the way to save money, you may have bad experiances after all.
But I have seen already peoply buying used stuff at EBAY for higher price than the new one. Thus...
Title: Re: Repair : Old rusty HP 3458A
Post by: Sbampato12 on September 21, 2015, 08:09:41 pm
But I have seen already peoply buying used stuff at EBAY for higher price than the new one. Thus...

I could never understand that... always find somethings like this on ebay or on locals websites... :-//
Title: Re: Repair : Old rusty HP 3458A
Post by: Smith on September 22, 2015, 06:41:23 am
Buying potential damaged tools is like playing in a lottery. Sometimes you are lucky and sometimes you don't.

Most people are probably interested after seeing so much 'succesfull' repairs on this forum. But I still wonder how much of these repairs fail due to funds or unobtanium parts and don't make it to the forum.

I know not every gear I have tried to repair succeeded. Maybe 75% did. Especially with scopes it's a wild guess.

Its nice to see this 3458A being brought back to live. Fortunately TiN seems to have the funds to do so, I think most people would have sold it again after seeing how much is needed to repair the thing.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 22, 2015, 10:52:11 am
I hope to have funds , hah. It's approaching "don't bother" region at pretty fast speed. :)

On a serious note, I am looking at it as way to learn something new, as way to create good content, be it repair worklog or teardown. If project end up with functioning machine, well it's another piece of gear to be used for no reason (:D) and likely some investment, as these things will be around next decade or two, no worries.

Little bird whispered to me, that HPAK confirmed order for parts and they have everything in stock :D
Title: Re: Repair : Old rusty HP 3458A
Post by: Smith on September 22, 2015, 11:37:34 am
Does the 8.5digit  interfere with your needs regarding the KX project?

By the way should we expect any progress on your KX project coming soon?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 22, 2015, 11:58:45 am
8.5 DMM does not solve signal generation task, which is project targeted for.
I'm doing some ADC/DAC evaluation currently, hope to post some updates relatively soon.
Title: Re: Repair : Old rusty HP 3458A
Post by: Smith on September 22, 2015, 12:02:39 pm
8.5 DMM does not solve signal generation task, which is project targeted for.
I'm doing some ADC/DAC evaluation currently, hope to post some updates relatively soon.

I meant your desired signal stability and repeatability to test (obviously not to calibrate) 8.5 digit meters.

Can't wait to see some updates, it's a verry interesting project.
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on September 22, 2015, 12:10:32 pm
That's the right way, TiN. Take it for the fun, not for the money.
If you save some money with your "hobby", it will be the cream.
I have done a lot of repairs of "vintage" tools so far (the oldest one is from ~1907 and operating).
I prefer tools that have been a mile stone in technology and which seem to be worth to be alive. I try to keep them as close as possible to the origin. But my first rule is to have fun, it's a hobby.
During the years I had to find ways to overcome unavailable parts. Thus I learned a lot on that clever "old style" solutions, about some basic I was not aware of and last but not least, on cleaning techniques.
There is just one critical point: the space required becomes more and more in conflict with my Girl.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 22, 2015, 01:17:09 pm
Same reason I took one, more for hobby and restoration. Same reason I restore reel to reel decks and other vintage electronics on the side. You will always get some that don't see the point, as they just look at it for profit and don't care about anything else and to me that sad.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 23, 2015, 04:50:23 am
Rear bezel from 4gte.com have arrived.  :)
Title: Re: Repair : Old rusty HP 3458A
Post by: deadlylover on September 24, 2015, 12:22:16 am
Good luck with the repair. ^^

You probably already know this, but Keysight offers 2 levels of calibration for the 3458A. There's the cheap less expensive one that's around ~$700 and then there's the standards lab cal at ~$2600 or so. IIRC, they had uncertainties on the 10VDC range of 3.6ppm and 0.2ppm respectively.

I do think the standards lab cal is slightly overkill for mere mortals like us...  :P
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 24, 2015, 06:07:21 pm
Since I wait for new transformer to arrive, how can we test inguard supply to confirm it's OK?

Glad you ask, I have a solution.  :-DD From previous Keithley Model 2001 repair projects I have one extra power transformer, which happen to have same voltage outputs, as HP one, just at lower power rating. But since we connect only inguard supply A4 board, we don't need full power to check LDO's operation. So let's replace blown zeners and test A4 PCBA with properly wired Keithley mains TR-280 transformer. Never know which parts could ever come handy, eh?  :-DMM

But first, replaced original CR11,CR12 with fresh zeners (got 50pcs from eBay, just few dollars with free shipping).

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/zeners_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/zeners.jpg)

Cleaned board both sides, everything else look intact and good.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_kei_mains_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_kei_mains.jpg)

Now can connect input IEC plug socket to transformer's primary (since I need 110VAC, I used WHITE + BLACK wires).

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_keitr_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_keitr.jpg)

Keithley used same type of 5-pin connector, but with different pinout. Secondary connector need rewiring as on photo above. I powered transformer separately and measured VAC voltages on secondary, without A4 board connected, to make sure all voltages correct.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_gnd_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_gnd.jpg)

If you see schematics of A4 board above, you may noticed MH1,MH2,MH3 connections. These are connected directly to guard frame in 3458A's chassis, which is acting as mecca star point for GND potential. Since I testing board separately, not mounted to chassis, I needed to connect these MH* points together with copper wire. This will be our ground point for measurements as well.

Apply power to transformer, and if nothing smokes, test output DC voltage.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_meas_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_meas.jpg)

There are nice labels near test points, telling us voltage test points location.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_18vdc_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_18vdc.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_n18vdc_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_n18vdc.jpg)
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_5v_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_5v.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_n20v_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a4_n20v.jpg)

All voltages are OK, also 0.325VAC 60Hz signal to read mains frequency is OK too.  :-+

Repair of A4 inguard power supply now complete.

I also got used bezel off eBay in good condition, to save some money on this project, as it's just mechanical part to keep meter in one piece.
New one on bottom side, old busted rear bezel is on top.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bezel_a_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bezel_a.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bezel_b_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bezel_b.jpg)

Original unit's bezel had three out of four screw mounts destroyed, so it was not holding well.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bezel_comp_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/bezel_comp.jpg)

Stay tuned...  :popcorn:
Title: Re: Repair : Old rusty HP 3458A
Post by: Towger on September 25, 2015, 08:08:41 am
Since I wait for new transformer to arrive, how can we test inguard supply to confirm it's OK?

I tried much the same, bypassing the PSU on a faulty monitor a couple of weeks ago. Unfortunately it did not have good results  :-//

Keep up the good work.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 25, 2015, 10:03:00 am
Beware doing such if your PSU is switching, as minimum load requirement not unusual for them, meaning that they will not work or even get damaged by operation without loading. Lot of SMPS have external feedback networks, which could go wacky if there is no connection to load.  :bullshit:
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 25, 2015, 02:32:02 pm
Some folks tend to say, that old equipment was designed much better than recent one, system and service wise... Well, I had zero problems tearing unit to pieces within 15 minutes and not even looking into service manual. Well done.

Then the hard part came - scrubbing steel chassis with alcohol from rust. God, it's messy. Gone thru two packs of 3M Scotchbrite already.
It does look cleaner, but some narrow areas still rusty. Photos later.

Also one thing came up to my memory, reading explosion stories here about EMI filters. I even found that thread, exploded 3458A (https://www.eevblog.com/forum/repair/hp3458a-schaffner-mains-line-filter-failure/msg489147/#msg489147). And yes, your guess is right, my 3458A having exactly same filter, Schaffner FN 323-3/05, made in first week of 1995. Going to order new Delta filter from Digikey ASAP :)

And DS1220Y-200+ showed up, fresh and nice, 6th week 2014.
DS1230's, transformer, mechanical parts and A9 LTZ1000 reference board should arrive anytime next week.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 26, 2015, 12:00:13 pm
Made an order on Digikey for fan, caps to recap A6 outguard power supply board (call me paranoid, but I don't trust 20 year old electrolyte capacitors.  :-BROKE).

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/part_digikey.png)

Only gotcha is that there was no axial type C8 8300uF 35V capacitor, so I got usual one of similar size instead, will bodge something up.  :-//

Also one thing catch my eye :

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/digit_power.png)

See anything suspicious?
Hint-hint : P3 connector goes directly to fan...
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 26, 2015, 12:10:53 pm
Overdriving a 12V FAN?

ETA: U2 must be a 7812 surely. 7815 on a 15V supply rail. Nah...
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 26, 2015, 01:36:35 pm
I see someone reading, great job :)

It does look like HP do overvoltage fan, unless they using 7815 in uncommon way by having low input voltage, perhaps?
I will definately take a measurement after new transformer installation.

CLIP's BOM does say it's 7815 as well:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan_reg.png)

Also this reply another possible question if fan run variable speed. No, it does not, 3458A is not quite a home appliance instrument, so FAN is always on max the moment you turn instrument on.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fanreg_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fanreg.jpg)

This LDO originally have little cute heatsink clip on it as well, I removed it for sake of marking photo.

Let's take a look on fan itself, with my favourite way : destructive analysis. Fan impeller is covered in gunk and barely moves by hand, so I don't care about it now.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan2.jpg)

It's made by PAPST, decent company with good reputation (as far as I know), sized 60x60x25mm and made in Germany. Let's crack it open, shall we?

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan3_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan3.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan4_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan4.jpg)

Eek, all those metal rusty particles.. It have dual ball-bearing suspension, original PAPST design. Rather neat fan it was.

Hint for fan replacements : save the wire. I usually desolder wire from old fan and replace it on a new fan, it's quicker for me than looking for same type of connector and adjusting wire length..

Couple extra photos for you, volt-nuts..

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_mcu_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fp_mcu.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_optical_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_optical.jpg)

Just look at that 8051 microcontroller, preprogrammed by Intel itself (laser-coded 3458-85502 mark) in 1993. It runs front panel interface code and handles speaker (by resetting 555 timer nearby :)).

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/dig5v_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/dig5v.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/vfd_dcdc_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/vfd_dcdc.jpg)

Big serious L296HT fella is main +5V regulator, which powers all A5 outguard controller board and rest of +5V consumers around. Brown PCB module is simple DC-DC/AC converter for VFD, similar to ones used in Keithley gear. It supply around 60 VDC to display glass segments and VAC voltage for filaments.

And now messy part : cleaning steel chassis frame. Tomorrow will be more cleaning, and hopefully moar pics.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mess_rust1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mess_rust1.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 26, 2015, 01:50:47 pm
I'm a little confused with the supply rail. I'm guessing CR3 is a 30V zener (not seen that symbol before), so it could be used as a 30V regulator or else some kind of over volt clamp on a lower voltage unregulated supply which would be about 15V looking at J15. That is too low for the 7815 drop out. Maybe it's a typo and it's something like 25V unregulated?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 26, 2015, 02:51:20 pm
I'll measure actual voltages when get all assembled.

Desoldered calibration NVRAM, DS1220, guess what, it's still seems OK.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/calok.png)

Not that it matters with last cal date in 1991, but still, interesting to know that even 25 year old NVRAM could be still storing all data.
Will replace it anyway, not to tease luck.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 26, 2015, 04:03:19 pm
I'll measure actual voltages when get all assembled.

Desoldered calibration NVRAM, DS1220, guess what, it's still seems OK.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/calok.png)

Not that it matters with last cal date in 1991, but still, interesting to know that even 25 year old NVRAM could be still storing all data.
Will replace it anyway, not to tease luck.

Quite surprise battery held up that long. Could be because it's well sealed.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on September 26, 2015, 04:51:28 pm
Hi TiN,
Save the content of the 2kx8 NVSRAM and copy to new one.

If these are the correct constants, fitting to  your DC board (7.15xxxV and 40.0xxxkOhm), and maybe also for the AC board, you may check drift, and perhaps do not need to recalibrate AC high frequency constants, only 10V and 10k, for your purpose.
Frank

Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on September 27, 2015, 01:22:33 am
Hi TiN,
Save the content of the 2kx8 NVSRAM and copy to new one.

If these are the correct constants, fitting to  your DC board (7.15xxxV and 40.0xxxkOhm), and maybe also for the AC board, you may check drift, and perhaps do not need to recalibrate AC high frequency constants, only 10V and 10k, for your purpose.
Frank

If TIN replace the reference board are the calibration data is still useful ?
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on September 27, 2015, 02:38:14 am
Hi TiN,
Save the content of the 2kx8 NVSRAM and copy to new one.

If these are the correct constants, fitting to  your DC board (7.15xxxV and 40.0xxxkOhm), and maybe also for the AC board, you may check drift, and perhaps do not need to recalibrate AC high frequency constants, only 10V and 10k, for your purpose.
Frank

If TIN replace the reference board are the calibration data is still useful ?

I would say it still would be useful. The reference boards should be close enough he will know if the unit appears to be working 100% even if off a little, with no cal data at all it may be very tough to know if it even works properly.
Title: Re: Repair : Old rusty HP 3458A
Post by: HighVoltage on September 27, 2015, 09:25:11 am
Really interesting thread to follow you on the restoration process.
Will be very interesting to see, how many hours you have put in to the project at the end.
I am looking forward to your next steps.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 27, 2015, 09:29:31 am
I will have full article on my site with summary on both money and time spent.

If have some ideas what to cover more, let me know :)

At this moment waiting for parts to arrive to continue.
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on September 27, 2015, 09:38:55 am
Thanks Tin for this interesting story :-)
I will also replace all input relays, it does not looks like meter from metrology lab.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on September 27, 2015, 11:52:39 am
I see someone reading, great job :)

It does look like HP do overvoltage fan, unless they using 7815 in uncommon way by having low input voltage, perhaps?
I will definately take a measurement after new transformer installation.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan1.jpg)

TiN,

for a solution for that puzzle, simply look on the sticker of the fan!

As usual for fans, 12V DC is the nominal voltage only.

This Papst fan is rated for 6 - 15V DC!
Therefore, 15V is no over voltage.

So it will spin a little bit faster and will provide more air flow than at 12V, this will also be specified in the datasheet.
Also, HP has taken that into account, when they tested for proper cooling.
Don't change this 15V supply, when you buy the new fan!

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: BravoV on September 27, 2015, 12:03:14 pm
Regarding the 60mm x 25mm DC fan, I got tons of NOS "quality" fans laying around collecting dust, namely Panaflo and Sanyo Denki (all made in "Japan") not those Chinese crap.

Although not 15 Volt, all are 12 Volt rated, not sure if this rating is suitable for your need.

Here part of my stock to give you the idea what I have, its free if you still have trouble sourcing quality fan of that size.

PM if you're interested.

(https://www.eevblog.com/forum/chat/tektronix-2200-series-fan-noise/?action=dlattach;attach=22114)
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on September 27, 2015, 02:46:25 pm
I do not understand why a multimeter need an "overvoltage" run fan is the heat generated inside of 3458A is so high ?
in case the fan use for regulated the temperature inside the 3458A why they do not use a variable speed ?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 27, 2015, 03:51:50 pm
Thanks for offer, but I already ordered NMB fan of same size and spec from Digikey :)

Dr.Frank

Just unusual to me to see powering fan from +15VDC. Not intended to change anything yet.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 28, 2015, 12:34:26 pm
While typhoon DUJUAN unleashes it's wraith on Taiwan, I spend few more exciting hours scrubbing chassis from rust.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame1.jpg)

Aluminum inner frame have date code marks too, MAY 04 1995 and May 23 1995, confirming theory that all meter boards, except A5 outguard controller are ~1995 year, while A5 is was swapped out to older 1990 board.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame2.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame4_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame4.jpg)

IEC mains socket was fixed to chassis with rivets, I'll use suitable screws instead with new socket.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame5_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame5.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame6_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame6.jpg)

Was using sandpaper grit 200 first, then 400, then 600A. Few spots around nuts and corners still need some attention, will do it later before assembly.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame3_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame3.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame8_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frame8.jpg)

Cleaned front panel from pesky stickers. It's almost mint now, satisfied with front face condition.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fpface1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fpface1.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fpface2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fpface2.jpg)

Cleaned keypad as well, who knows whose dirty fingers pressed teh buttons :)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/keypad_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/keypad.jpg)

So far spent ~2 hours on cleaning.
Title: Re: Repair : Old rusty HP 3458A
Post by: LINACboy on September 28, 2015, 01:35:08 pm
Had to replace the fan in my unit, too. The bearing was worn out and the balls were producing this painful grinding sound that instinctively makes you cross your legs...

My replacement fan is a Pabst Type 614 NGM (24V rated). It produces subjectively equal air flow (wet finger test) when powered by the DMM.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 28, 2015, 01:43:05 pm
I wonder where did OldSchoolTechCorner disappear? He should get his rusty 3458A already, I believe.  :D
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on September 28, 2015, 02:19:07 pm
Great job on the cleaning. I like the idea of removing any trace of the previous users. It makes me feel like I am the original owner of a used car.

I had to replace a fan in a 3458A. It was old enough to be made in West Germany. I believe the replacement was a Papst 622L. Ebm-Papst had no records of my fan, they must have cleaned house a few decades ago.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 28, 2015, 02:24:30 pm
My Digikey box just shipped. :) Let's see how quick it will come. 
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on September 28, 2015, 03:09:00 pm
Still around, just working on another project,"New workbench".
Title: Re: Repair : Old rusty HP 3458A
Post by: robrenz on September 28, 2015, 04:54:45 pm
Very nice restore work there TiN  :-+ :clap: keep it coming
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 28, 2015, 05:28:01 pm
OldSchoolTechCorner, I can't wait to see what's inside your unit.

While waiting for parts, I now took a close look on analog boards.

A1 board

This board also have mark "X" around reference header, also paper tape sticker "X" in center of board near RP7 resistor network. Visual inspection shows ugly soldering and flux around parts U300, U305, U301, RP300, U304, U306, RP301, U303, RP302, RP303, R308, R307, R310, RP200 and around all relays (K1, K2, K3, K4, K5, K6, K7, K9, K200, K201, K202, K203, K204). Relays have datecodes from 1997, while rest of the board IC's dated 1995-1996. Previous owner tried to fix board by replacing relays?

Looking not good, if you ask me. Those COTO relays, HP resistor network RP300 are unobtanium. U300 OPA111BM is rather expensive too, 50 USD a pop on Digikey.

I claim world-record highest resolution photos of 3458A stuff ever,  :-DD That's what happening, when photo-nut comes to volt-nuttery...

98MP, front side.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_pcb_hires_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_pcb_hires_top.jpg)

96MP back side.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_pcb_hires_back_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_pcb_hires_back.jpg)

Soldering "job"

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_solder.jpg)

Some people just don't know what they are doing in terms of repairs :(. That's why buying gear "after repair" sucks, often it's worse as than getting unknown, never serviced gear.

Rest of boards seem to be OK looking

A2 PCBA:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_top.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_bot.jpg)

Rest of details on this board:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_cap_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_cap.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_rev_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_rev.jpg)

That piece of wire looks interesting, funky low-capacitance capacitor, perhaps?

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_gold_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_gold.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_grd_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_grd.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz1.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz3_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz3.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz4_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz4.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz2.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz5_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz5.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz6_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_hz6.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_tpoint_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_tpoint.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_cap2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_cap2.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_caps_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_caps.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_port_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_port.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_s1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_s1.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_shield_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a2_shield.jpg)

A3 ADC PCBA:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_top.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_bot.jpg)

Rest of details on this board:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_opamps_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_opamps.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic2.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_lincap_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_lincap.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_logic_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_logic.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_mcu_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_mcu.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_optic_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_optic.jpg)

Also another thing I noticed, guard traces are covered with soldermask. Isn't that defeat purpose of guard trace? Or it was an issue to manufacture with open copper in 90's?


Title: Re: Repair : Old rusty HP 3458A
Post by: MadTux on September 28, 2015, 05:36:10 pm
That flux residue usually dissolves easily in ethanol or isopropanol. Maybe resolder the questionable joints and then dump the board into a bucket/dish filled with EtOH or IprOH.

Are you using image stitching like hugin btw? That MC14094 shows some artifacs  ;)
I usually use scanners to make board photos, they have more resolution and cost far less than good camera. My trashpicked Microtek Scanmaster i900 can do these resolutions in one shot.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 28, 2015, 05:41:49 pm
I would approach zone area cleaning for such analog board, there are signals and isolation requirements, which are not forgiving treatment style "dump and wash all together", usual for popular digital stuff.
And I need get few bottles of clean IPA first.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 28, 2015, 05:53:44 pm
Yes, just stitched together in photoeditor manually, 10 minutes for a set (4 photos each, 36Mp each, shot with Sigma Macro 150mm lens).
Scanners have crappy depth of field and unusable for shiny parts, like metal cans.  :box: And they are bulky and obsolete  :P
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 28, 2015, 06:01:39 pm
Fantastic photos. Why I think I could even clone a 3458A from scratch, etching my own double sided PCB's from them  :-DD

Now those little blue "solder pots" buried in the PCB and the little white standoffs with solder posts on and the holes drilled all around them are especially intriguing. That stuff is total voodoo to me.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on September 28, 2015, 06:02:55 pm
I'll trade you....  >:D

I bought this for future salvaging. The cables, relays, and resistors would cost a lot more than what I paid for it. Unfortunately, someone let out the magic smoke.

I have grabbed a few boards for the 3458A's. If you need a part or two, we can arrange something.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 28, 2015, 06:05:56 pm
Should not be very hard, as all boards are dual-sided thru-hole only, unlike Keithley's boards  :-X

Standoffs and leg-leg posts are due PCB surface is too leaky for those sensitive circuits. Even few nanoamps of parasitic current could easily upset operation, causing error in measurement and all random issues. That's why touching such with fingers circuits is a big no-no, as skin oil will cause unwanted current flows around. Teflon and air are much better insulators than FR4 PCB, so that's common practice for high-impedance circuit design.

ManateeMafia

Lol, I was looking on that one, wondering who snagged it. No wonder, who. :)
Hold it till I get solid test results and data on my gear. Work cancelled tomorrow as well due to typhoon, so no packages with parts tomorrow :(
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 29, 2015, 02:08:38 pm
More cleaning, this time outer covers.

This is what we had to deal with:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cover_before_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cover_before.jpg)

After a hour of scrubbing with scotchbrite, here's the result:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cov1_after_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cov1_after.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cov2_after_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cov2_after.jpg)

Few marks left in corners, will deal with that later before final assembly.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cov_side_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/cov_side.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frames_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/frames.jpg)

It start to take shape. I'd say improved condition from level 3-- to somewhat level 4.

Tomorrow should get some goodies from post. Can't wait!
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on September 29, 2015, 03:28:20 pm
It is good to see you made it through the typhoon.

I typically use Simple Green first and follow with alcohol. It looks like some of the plastic skin is peeling away from the edges. Do you think that the aluminum is corroded under the plastic? My calibrated 3458A has no plastic, somewhere before me someone stripped it off and painted the bare aluminum with an epoxy paint.

I asked the folks at Loveland about customizing the covers and they told me that they get some every once in a while. I think they said they got one that was painted red. I had another set of covers that were permanently stained from a sharpie, so I used Krylon Fusion paint. The color matches my old Fluke gear and made a huge difference in how it looked.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 29, 2015, 03:48:00 pm
I'd love to see that. Graffiti 3458A anyone?  :-/O Gives +5 to precision feel. So folks on calibration lab don't usually give a dam about looks, as far as box works? That's nice of them.

Alu covers seem okay, it was just mechanical damage on corner, seems like.

Here's bonus for today. Exploded view of 3458A parts (except A9 reference board, so shown my LTZ ref instead as placeholder :))

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/exploded_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/exploded.jpg)

Better to view full-size on click.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on September 29, 2015, 04:12:15 pm
 :-+

This would make a good desktop background to replace one of my 3458A pics. Too bad one of my monitors just died this morning.... It looks like my to-do list just got bigger.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on September 29, 2015, 04:35:32 pm
After a hour of scrubbing with scotchbrite, here's the result:
Ahh, yes, when tackling mundane cleaning tasks like this it's always good to have a bottle of beer or two to help relieve the monotony.

Now that Taiwanese beer in the top left corner of your pics, 95% alcohol  :phew: That's some mighty stuff!  :-DD  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on September 29, 2015, 05:32:41 pm
For similar cleaning tasks I used Cif Lemon with quite good results.It is not so powerfull as Scotch brite, but can dissolve lot of nasty stuff on old equipment.
http://www.amazon.com/Cif-Cream-Lemon-Fresh-500ml/dp/B00N4PVDJ0 (http://www.amazon.com/Cif-Cream-Lemon-Fresh-500ml/dp/B00N4PVDJ0)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 30, 2015, 03:59:27 pm
Got two fresh bottles of IPA 500ml. I'm ready now.

Also received 5pcs DS1230Y's.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_mem_opt1_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_mem_opt1.jpg)

Pity only 2 out of 5 works, rest giving errors with TL866. eBay is so eBay  :P

Meter digital side now starts, pass checksum and RAM tests, and giving ISOLATION ERROR (of course, nothing from analog side is even connected).
Title: Re: Repair : Old rusty HP 3458A
Post by: vtp on September 30, 2015, 05:50:42 pm
(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_mem_opt1_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_mem_opt1.jpg)

That looks weird. U123 - U126 (if I am reading ref designators right) the four rightmost DS1230 NVRAMS in the picture should be volatile SRAMs 32kx8 (HM62256LP-12 in mine). I guess someone wanted to have non-volatile option 001.

I see you have REV6 firmware there. Easy enough to upgrade to REV8 or 9 by burning some new EPROMs. I did to REV8, comparing to REV9 there is not much difference.

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on September 30, 2015, 06:58:44 pm
Yey, success. This photo generated some head scratching! It's just for fun.
I don't have 32x8 memories at moment, but that's not important so far, as need repair meter first.

Firmware upgrades, tweaks, options will all be done much later, after we get all basic function and repairs complete.  ;)


Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 01, 2015, 10:52:01 am
What is it, a little birdie brought something to us today?

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_side_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_side.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_top.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_bot.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_r1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_r1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_r2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_r2.jpg)

Will it work?





Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 01, 2015, 11:29:29 am
Well the LTZ1000 doesn't look like the pieces of turd I got (https://www.eevblog.com/forum/projects/ltz1000-heater-resistance-possible-fakes/).  :-DD

I'm sure you can knock up a test rig and leave it running to track its performance over the coming weeks while you get on with the rest of the job?  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 01, 2015, 11:33:07 am
What is it, a little birdie brought something to us today?

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_side_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_side.jpg)


Will it work?

Definitely, looks like an original board.

The reference is missing the plastic caps, on top and bottom, for the urgently necessary protection against air draught.

I also recommend to directly pimp this reference to 65°C. (quasi opt 02)
If you do so, you won't need the original plastic caps, which need to withstand the 95°C oven temperature.

FW version 8 is recommended, as the elder ones still contain some bugs.
9 is identical in functionality, only a few bytes were changed (unknown relevance)

You also assembled nv-SRAMs for the opt 1 memory (+128kB).. nice idea.. that might save its content, if the FW does not initialize it always during boot.. please report, if that works.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 01, 2015, 11:36:07 am
Weeks? Excuse me, I don't have so much patience, man.

Digikey box with fan, caps and mains filter should be here tomorrow, and only Keysight parts package stuck somewhere in Taiwan's airport :(

I'll run tests on LTZ module today, interested to compare it to my own LTZ modules. Probably will put both into foam box with TEC and measure them over 25 to 50C temperature span. Resistors used in HP module are not that amazing.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 01, 2015, 11:42:02 am
Dr.Frank, I'll do it all, believe me. Something tells me, that you did not see actual article draft (http://xdevs.com/fix/hp3458a/) I'm working on as repair advances. It have all details you are talking about, including modification details, which you covered on voltnut list. ;)

eBay seller also decent guy, and agreed to send 3 new DS1230's, no questions or return asked. Thumbs up for them.

I'll use pieces of hitemp foam around zener first.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 01, 2015, 03:23:00 pm
It's alive!

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_vmeas_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_vmeas.jpg)

About +7.07421 VDC @26.5°C ambient. My 2002 is few ~30ppm's low compared to 2001 Cal, but it's somewhere there.
One good thing about used references, they likely to be nicely aged. LTZ1000A on this one is made in 1993, in case someone miss it. Zeners like wine, only better with time.
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on October 01, 2015, 06:41:00 pm
Quote
    **
Dr.Frank, I'll do it all, believe me. Something tells me, that you did not see actual article draft I'm working on as repair advances. It have all details you are talking about, including modification details, which you covered on voltnut list. ;)
I have read, very nice and informative, seems to be a bunch of work.
What the reason to not list the specs of the still available tools in you comparison?
It may good also helpful to note, what timeframe the spec is given for (I assume it s the 1 year accuracy).
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 02, 2015, 04:23:54 am
Mmm, I don't see need of doing that, as specification are easy to find, and it's a lot of data and tables to mess with.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 03, 2015, 04:24:09 pm
Guilty by age

That's it, you read it correct. While my package with urgently needed new transformer sitting in post office warehouse, collecting dust, I decided to finish up with outguard boards.

Since I bet all of you already tired as hell watching multimegabyte photos, let's do something different today:

Timelapse (https://www.youtube.com/watch?v=HT4WFMk9ieU#)

5 hours worth timelapse, one shot every minute, 4K resolution. Actually I wanted livestream on youtube first, but they changed stuff around again, need use some dodgy 3rd party software (NONE of which worked on my Win2008, DOH!), so I gave up after waste of 1 hour, and used my trusty repaired Nikon D3 (http://xdevs.com/fix/d3_repair/) to shot timelapse.

-----

Alright, what was going on there?

A5 board

Replaced original rusty GPIB connector with fresh one from dead 33120A PCB, I had around.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_gpib_repair_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_gpib_repair.jpg)

Quiz for readers : what are those funny traces with cutout do?  :-/O

After connector replacement (had to saw it a bit, as it's mounted to PCB using rivets!). No, I don't have a drill, so used hand mill instead.

Then boring part, water+IPA bath for PCBA:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_gpib_fix_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_gpib_fix.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_clean_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_clean.jpg)

A6 board

Now while A5 rests drying out, I took a close look on A6 outguard PSU board.

Removing VFD supply boardie:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/vfd_psu_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/vfd_psu_top.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/vfd_psu_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/vfd_psu_bot.jpg)

It's a TDK-CD1867N DC-DC/DC-AC module (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/pdf/TDK-CD1867N.pdf)

Now since monday I will have my Digikey package with new caps, I removed old ones. They looked alright, so most of you guys would think - hey, those caps probably okay, don't waste your time?

Nah, better be safe than sorry... Get out!

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_caps_bad_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_caps_bad.jpg)

Oh boy...  :-- Mr.Leaky there..

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_caps_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_caps.jpg)

Small ones did not do any damage (yet), but bigger ones...

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap2.jpg)

Oh-ho-ho. Glad I removed them. And glad HP 3458A using only 2-layer PCBs, so I'll just clean it to shiny copper, add thermal-resistant mylar cover around pins , just in case.
Caps I bought are long-life 5000hrs @+105°C, so should work a treat.

I was wondering and measured old caps too, for series capacitance and resistance:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest1.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest2.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest3_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest3.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest4_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest4.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest5_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest5.jpg)(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest6_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_ctest6.jpg)

I have few more videos (usual ones, not timelapse) of cleaning. I can upload that too, if anyone wants here. It's boring tho.

So people, learn the lesson today, capacitors are only worse with age, not better like voltage references. 10 years passed? Replace them now!
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 03, 2015, 05:32:33 pm
I have a couple that are older than yours. I guess I will have to add some caps to my next order and save it for a rainy day project. Have you decided to replace the large one on the inguard ps? I think it is C09. I don't see it on your Digi-key order.

No idea about the traces. They appear to be used as decoupling capacitors.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 03, 2015, 05:39:42 pm
C09 later, Digikey have none in stock.
C08 and C07 2200uF 35V's I already had, no leaking on board from original ones, so I did not take a photo.

Also I had A9 board running last few days non-stop, recording max/min deviation, and recorded it as 3uV/-7uV ,
which according to my room temperature span about 6°C, gives relative stability about than 0.02ppm/C, combined with LTZ1000A in K2002 itself (as I'm not sure if my K2002 goes up or down with temperature rise).

There is no useful meaning of this data, except fact that it's not doing any sketchy business and stays where it should be. So I'm pretty confident now to use A9 REF from eBay in 3458A on monday.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on October 03, 2015, 06:21:04 pm
I can't wait till get mines, as planning a OCD restoration on it. Always change the capacitors, they will destroy the traces and pads, as electrolyte act as a acid, even if they test good. 
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 03, 2015, 06:25:18 pm
OCD? I can't wait for yours too, double fun is better than single! Join us  :blah:
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on October 03, 2015, 09:59:37 pm

Quiz for readers : what are those funny traces with cutout do?  :-/O


Spark gap I am thinking.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 03, 2015, 11:11:58 pm
Never mind all that, I had to laugh at that funny little black gremlin introduced around 00:15 in the video (and quickly disappeared)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 04, 2015, 05:34:10 am
TheSteve  :-+, Bingo. I believe Dave was explaining this kind of spark gaps on PSU PCB before in some episode in the past.

Macbeth  :-DD Quickly disappearing gremlin made my morning. New mascot?  ^-^
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 04:38:42 am
Yey, I got parts. Christmas came early in this house  ^-^  :popcorn:

And it's obvious I screw up with Digikey's order, as got only 1pcs 680uF 50V capacitor ,while need two.  :palm:
Will have to do quick run to local electronic stores to see if I can snag some caps.

Photos and video are coming tonight.  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on October 05, 2015, 12:55:38 pm
@ TIN, How many hours You sleep every day ?  :-+

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 01:03:16 pm
Sleep? What is that. :)

Just got extra caps. Local shops have nothing, only crappy nonames most of the time, forget alone axial high capacitance caps. Will bodge radial 8200uF one instead on axial on A6 board.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 05:47:25 pm
Alright, assembled everything back together (sorta), getting ISOLATOR FAILURE. Voltages out of inguard PSU are fine now (5.004, +18.34, -18.66, -21.x), LTZ gives it's 7.07VDC, fan receiving it's 15V, but getting stuck with this isolator thingy...
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 05:59:28 pm
Hm, I have a suspect - transmitter J102, I can barely see it's red light, while other ones are pretty bright red. Perhaps dodgy LED in it?
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 05, 2015, 06:03:31 pm
I was going to suggest swapping the fiber cables from the rear trigger input. They are not needed for self-test. You can always steal the tx/rx from the trigger i/o.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 06:07:01 pm
Fiber is ok. I guess time to blow dust out of my CSA7404 scope and see some waveforms...

This weak light out of J102 not in my liking. But I could be wrong...
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 05, 2015, 06:23:27 pm
I found the datasheet and emailed it to you. The file size is too big.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 07:05:59 pm
Not my lucky day I think.

I had datasheet both HP and Agilent.

Scope decided to die on me too, NVRAM battery died, 0.4V  :-BROKE
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 05, 2015, 07:13:48 pm
Not good. The more equipment you own, the more likely something, somewhere, is going to die when you least expect it.

Is it possible to mount a remote battery holder for the NVRAM? I am guessing it is the one you replaced under the PowerCAP? https://www.eevblog.com/forum/testgear/tek-csa7404-repair-project/ (https://www.eevblog.com/forum/testgear/tek-csa7404-repair-project/)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 08:02:35 pm
NVRAM chip dead, failing tests even with 3.6V LiPo bat hanging on it.  :-\

What was multimeter repair quickly become scope repair. Not expected detour, tbh.

(http://xdevs.com/doc/xDevs.com/Lab/dead_scope.png)

(http://xdevs.com/doc/xDevs.com/Lab/dead_scope2.jpg)

I guess I'd better go sleep, unless something else died more. (4am here)

Good news - no smoke from DMM. Since I'll be ordering new NVRAM for pesky scope, I'll order optical receiver/transmitters too, but will need more testing.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 05, 2015, 08:23:08 pm
It's that little black gremlin I tell ya. Got to keep an eye on him!  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 08:29:20 pm
Timelapse of today, one photo every 7 seconds

Timelapse 2 (https://www.youtube.com/watch?v=TJB_iT8SGwo)

Sorry for glare, had to have lots of light to see what's going on.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 05, 2015, 08:51:56 pm
Plan B for tomorrow : hook my TLA714 on optical interfaces and see whats there. I hope it's not also dead (LA), last time I turn it on half year ago.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 04:07:24 am
(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/iso_blk.png)

Here's the battle-field, to summarize in a block diagram. Hope it's not problem in ASICs, as that would be a problem  :-//.
Title: Re: Repair : Old rusty HP 3458A
Post by: HighVoltage on October 06, 2015, 07:43:03 am
Timelapse of today, one photo every 7 seconds
Very impressive, I watched it halve that speed in VLC.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 02:54:38 pm
Doh, LA died too. Well, LCD flickering like crazy, probably driver or panel gone bad. I don't use it locally, only by LAN anyway, but that's following bad trend here..

Ok, probed around U700..

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/test_u700_1.png)

That RSXGD- signal out of U106 PAL looks strange, causing RESETs on U700.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 04:03:48 pm
If you are pretty certain the pal is toast, do you have equipment to verify that the read protect bit is not set?

I think there may be a pal or two available from HAK. I don't have a way to r/w pals but it might not matter if the protect bit is set. Of course, there may be other solutions.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 04:17:07 pm
Their finder for parts does not have these ones (03458-88804). PAL is AMD MMI 8L14 Decoder logic.

I don't have anything, never worked with PALs before, only CPLDs. MiniPro does not support these ones either.

Found few datasheets if it's sctructure:

AMD's PAL Handbook, 31MB (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/pdf/1988_AMD_PAL_Device_Handbook.pdf)
8L14 series DS (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/pdf/AMDIS01840-1.pdf).

I could bodge little ALTERA MAX instead of it, but need to find out logic which goes into that decoder...

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/pal.png)

Easy things to try - disconnect PAL's pin from board and check if any difference. I will do this tomorrow to check, also capture all PAL signals.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 04:50:33 pm
I will research what I have available to me and let you know if I can come up with something.

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 04:56:00 pm
If you have scope or better, LA and time, signal capture on RSXGD- during power on would be super helpful. This would narrow down suspects to PAL or PALs input circuitry.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 05:21:59 pm
I have a Saleae logic analyser. Only 8 channels but I think you were only looking at 7 (max), correct?

Did you mean U700 or U100? The clip is hard to read but I think you meant U100.


Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 05:23:35 pm
Never mind, found U700 in the corner of the page.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 05:25:26 pm
2 channels enough :). U700 pin 3 (reset) and U106 pin 23 (rsxgd-). U106 is top pal with 03458-88804 sticker, U700 big 40 leg ASIC.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 05:32:23 pm
OK. I will get you some screenshots. It has been a while since I used this thing.
Title: Re: Repair : Old rusty HP 3458A
Post by: guido on October 06, 2015, 05:47:54 pm
That RSXGD- signal out of U106 PAL looks strange, causing RESETs on U700.

Mmm. No answer on R_Data, so the processor running the show resets the interface?

Try following the serial data towards U210 and see if it gets there. And if there is an answer, see where it stops.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 05:50:22 pm
Yes, will do that as well. 2 am here already, another crazy day :).
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 06:54:09 pm
It took longer than planned. I had to take a pic as my software will not do screen capture with this version. It is not clear but the top line is U700.3, second is U106.23, and third is U700.1.
4th is from the 8MHz osc.

The data collection was started after I did a SHIFT-RESET. I will try again with power-on.

I will download the latest version in case more data needs to be collected.

I am not capturing a reset on U106.23. The reset line is being held low for 2us.


Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 06:59:43 pm
I am changing my settings, I think I am missing the trigger on u106.23
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 06, 2015, 07:12:59 pm
This time I was able to capture some traffic. The first reset does not cause any change to U106.23 . There is a change 2s10ms after the reset.
I installed some beta software and the pics are easier to look at. Sorry about the last worthless one.

I hope this helps!

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 07:33:22 pm
Thanks.
I got idea now that PAL is working.
Traced signal path of transmit...Signal after U700 ok, signal after U100F - ok, Signal on cap C104 - ok, Signal on CR104 anode - ok, singal on J102 optical transmitter - stuck high...
Loose my temper and shorted anode of CR101 to U302 pin 9 input on A3 A/D board. Guess what, it booted and let me to UI.
It does not sample anything except FREQ and PERIOD, but it could be just set on some hold or trigger manual mode, never used HP DMM before...

It does lit up ERR with next errors:

202,"HARDWARE FAILURE -- SLAVE TEST: CONVERGENCE"
110,"CALIBRATION REQUIRED -- ACAL"

Nothing else.

If I try run ACAL ALL, it says 205,"HARDWARE FAILURE -- CAL VALUE OUT OF RANGE: 72"

Update, it's TARM command, now it's sampling... :-DD

Update 2: Doh, interface of 3458A definately not for bench use from front panel, user unfriendly  >:D Yah, I got spoilt with Keithley dual-screen display and menu system...

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 06, 2015, 07:57:18 pm
LA capture:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/test_2_s.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/test_2_s.png)

Photo of dodgy test setup: Note ground and white TX line from A6 to A3.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/iso_a6_fail_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/iso_a6_fail.jpg)

UI photos:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag1_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag1.jpg)(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag2_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag2.jpg)
(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag3_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag3.jpg)(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag4_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag4.jpg)

Time to go bed, 3:57 AM, again. But got some direction, that's hope. ADC working, digital A5 working, now fix optical issues (transmitter/receivers are easy to buy from Digikey) and will be time to debug A1 DCV board.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on October 06, 2015, 08:15:21 pm
Did just get mines today and did come with voltage reference board. Here a quick inside look before restoration, already found couple issues.

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_142605_zpsp1ogmg81.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_142605_zpsp1ogmg81.jpg.html)


(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_142629_zps5ipeoimx.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_142629_zps5ipeoimx.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_143545_zpseg9o4fxc.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_143545_zpseg9o4fxc.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_143552_zpsd4avepxu.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_143552_zpsd4avepxu.jpg.html)

Corrosion on leads

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_143711_zpsmga3ezmi.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_143711_zpsmga3ezmi.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_143813_zpsibiqjy4v.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_143813_zpsibiqjy4v.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_143819_zps7vjmcstc.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_143819_zps7vjmcstc.jpg.html)

Claim to be defective, will check later, is open, or shorted windings, before assuming. As could just be a power supply issue.

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_143823_zpsayvie8af.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_143823_zpsayvie8af.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_144201_zpsillchf0v.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_144201_zpsillchf0v.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_144209_zpseespnxls.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_144209_zpseespnxls.jpg.html)

Not as bad as I was expecting, sure clean up nicely

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_144220_zpsuah3lode.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_144220_zpsuah3lode.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_144322_zpswubgm6m9.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_144322_zpswubgm6m9.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_144330_zps1qpc7dp0.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_144330_zps1qpc7dp0.jpg.html)

Looks like one issue.

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_144335_zps2peorhxs.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_144335_zps2peorhxs.jpg.html)

(http://i1220.photobucket.com/albums/dd456/retropcdos/20151006_144348_zps6lmdiya0.jpg) (http://s1220.photobucket.com/user/retropcdos/media/20151006_144348_zps6lmdiya0.jpg.html)

Title: Re: Repair : Old rusty HP 3458A
Post by: Vgkid on October 06, 2015, 08:48:39 pm
Looking forward to the flood of 3458a repairs...
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on October 06, 2015, 09:16:40 pm
Looking forward to the flood of 3458a repairs...

Hmmm, "flood" - no pun intended?
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 06, 2015, 10:08:40 pm
To both of you, TiN and OldSchoolTechCorner,

I'll keep my fingers crossed, that you both succeed in repairing your 3458As.

What you are doing, is really a tough job, nearly like building it from the scratch..

If any comparison to a working unit is needed, just raise your hand..

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Vgkid on October 06, 2015, 10:10:35 pm
Looking forward to the flood of 3458a repairs...

Hmmm, "flood" - no pun intended?
pun intended
:hide
 >:D
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 07, 2015, 12:33:56 am
Yeah! Congrats on your toy arrival, it does indeed look like less cleaning required :)

 Those burnt zeners are likely indication of dead xfrmr, as they sit straight on output winding. I added detail and measurement results comparison on my xfrmrs in article (http://xdevs.com/fix/hp3458a/).

Your A5 board newer, wonder why there is X on ROM chip.
But same as mine , A5 date codes not matching analog boards, so likely was swapped.

 Drop me your address in PM, i'll send you some capacitors for A6 and zeners for A4.

Dr. Frank

Thanks! All of people posting here motivate us to do all this stuff. Best community, ever. Hey, i spent almost 3 years from time to time, reversing Keithley's 4 layer analog brd, this is piece of cake :D

We just hope for easy repair, like replace diode and 7815 and everything ok , lol. But not the case, this units take some sweat, that's for sure.

I bet seller reading all this and having great fun too. Join the forum, reveal yourself. We can help sell rest of rusty 3458A inventory in no time ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on October 07, 2015, 01:26:31 am
Yeah! Congrats on your toy arrival, it does indeed look like less cleaning required :)

 Those burnt zeners are likely indication of dead xfrmr, as they sit straight on output winding. I added detail and measurement results comparison on my xfrmrs in article (http://xdevs.com/fix/hp3458a/).

Your A5 board newer, wonder why there is X on ROM chip.
But same as mine , A5 date codes not matching analog boards, so likely was swapped.

Going to pull it later, looking at burnt zeners, output winding more likely overheated in the process and is more likely shot measure it later once finish with other project. I was wondering about the X marking, will soon enough find out
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 07, 2015, 07:11:07 am
Yeah! Congrats on your toy arrival, it does indeed look like less cleaning required :)

 Those burnt zeners are likely indication of dead xfrmr, as they sit straight on output winding. I added detail and measurement results comparison on my xfrmrs in article (http://xdevs.com/fix/hp3458a/).

Your A5 board newer, wonder why there is X on ROM chip.
But same as mine , A5 date codes not matching analog boards, so likely was swapped.

Going to pull it later, looking at burnt zeners, output winding more likely overheated in the process and is more likely shot measure it later once finish with other project. I was wondering about the X marking, will soon enough find out
It looks like yours is in better nick than TiN's was. You got a ref board at least (with insulating cap - have you checked what version of LTZ1000/A you have in there?)

TiN has a very nice VFD while yours is unknown at this point. I hope it's a goodun  :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 07, 2015, 12:56:20 pm
Seems like A3,A1 boards are much older on O's unit, datecodes 1988 (!).

There is interesting difference, on A3 A/D board, his board have U213 populated, while mine and photos on web of newer A3 boards show no chip there and a jumpwire from pin 8 to 10.
Chip location near 20MHz oscillator in center of board..

Swapped receivers on A3 board (used external trigger one ) - now optical interface works fine. It was a receiver U301 dodgy..
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 07, 2015, 02:13:20 pm
I have seen the same missing part. It is not noted in the CLIP IIRC. It doesn't seem to have an effect on the board and its removal may be part of a service note from HP. They mentioned having to swap out A3 boards for issues with the rundown conversion here ... http://cp.literature.agilent.com/litweb/pdf/3458A-07B.pdf (http://cp.literature.agilent.com/litweb/pdf/3458A-07B.pdf)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 07, 2015, 02:36:52 pm
Yes, I saw it, as well as all other service notes :)

Yesterday was first time I ran out of hooks for LA... :

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla_hooks_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla_hooks.jpg)

And that's correct. Only hardcore, only oldschool, using by bodge to generate UV for UVEPROM erase, so I can flash latest 9.2 firmware.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/uverase_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/uverase.jpg)

Next steps:

A1 DC board debug.

Symptoms:

DCV (any range) reading as near zero, but should be bouncing around on 10VDC and lower as it's >10GOhm impedance. So something somewhere cause too low impedance/short.
Ohms reading near zero for 10K and higher ranges, but OVLD for lower.
Current reading something microamps

ACAL gives error - out of range for constant 72, which is dcv gain 10V

Also how do I disable pesky BEEPs on every keypress? If I enter BEEP OFF and press enter, it just beeps once, go back to measurement and nothing changes, still beeping.  :palm:
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 07, 2015, 03:08:46 pm
I think I have seen you use that light before  ;D

Service note 18A mentions short term drift correction. Maybe a 10V cal needs to be performed so it knows what the new reference voltage is? I would think it would be happy then.

I don't know if the beeps can be disabled without running some wire and a toggle switch....

Do you still have a missing jumper from header P100 next to the reference board. I was looking at your pictures and it looks like a jumper is missing. I have a jumper installed between Normal pins 2&5. It is also there on my burnt A1. Schematic shows it as signal DC_AD from J2.6
Title: Re: Repair : Old rusty HP 3458A
Post by: Zucca on October 07, 2015, 04:00:22 pm
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_clean_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a5_clean.jpg)

I wonder if that plastic brush will create some dangerous ESD crap...mmm probably not in water... for a few dollars I got an ESD brush... don´t know if it was necessary but better to be safe than sorry.

Anyway, another TiN masterpiece. It is like watching some alpinist climbing the Everest.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 07, 2015, 04:24:15 pm
 :-DD :-DD :-DD

TiN -> Doh! :palm:

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_vref_sel.jpg)

Next time I come by Florida, I'll buy you any drink you want  :-DD
I mean, there is not zero chance that I could spent days of debugging instead of popping that jumper in, as I'd rather think about some complicated problem on component level, instead of checking multiple photos of other 3458A boards I saved on drive all these years...

Measuring +10.0006 VDC from SMU:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b10_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b10.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b10k_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b10k.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b1ko_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b1ko.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b1kk_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_b1kk.jpg)

Ohms mode

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i2.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i3_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i3.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i4_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diag_i4.jpg)

DCI ranges 10nA, 100nA, 1uA, 10uA, 100uA showin zero, no matter what current supplied into meter. So those ranges are broken. That cause self-test fail on value 95 as well.
DCI ranges 1mA and up are fine.

True people say - one set of eyes is good, but fresh eye always better  :-DMM :-DMM :-DMM
So happy now.

Video with Self-test, ACAL attempt and some tests.

3458A Try 3 (https://www.youtube.com/watch?v=8ij_DUCQuNM)

Firmware 9.2 is in the unit.

Current range should be relatively easy fix from now on. I'll leave it for tomorrow...

P.S. As much as 3458A awesome in terms of performance, I think that's much it's HORRID in front-panel operation. I used it for two days, but already hate it.
I mean really, it's hard to remember all those paths and combinations. I understand the target group of 9500$USD multimeter, but still. Now I completely understand why instrument like Keithley 7510 would be much better choice for bench use, if one does not need performance of 3458A.
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on October 07, 2015, 04:47:04 pm
Top work TiN - nice to see there is a pulse and it is almost fully back to life.
Title: Re: Repair : Old rusty HP 3458A
Post by: macboy on October 07, 2015, 05:01:21 pm
Very nice work  :-+
Are you still hard-wiring to bypass the fiber optic isolation?
Title: Re: Repair : Old rusty HP 3458A
Post by: HighVoltage on October 07, 2015, 05:03:28 pm
I understand the target group of 9500$USD multimeter, but still.

May be more .... What is wrong with this dude, asking US $15,600.00
http://www.ebay.com/itm/Keysight-Agilent-3458A-001-002-Digital-Multimeter-8-Digit-/141587046591?hash=item20f73ee0bf (http://www.ebay.com/itm/Keysight-Agilent-3458A-001-002-Digital-Multimeter-8-Digit-/141587046591?hash=item20f73ee0bf)

It is really nice watching you in fixing this great instrument.
Title: Re: Repair : Old rusty HP 3458A
Post by: Jwalling on October 07, 2015, 05:27:24 pm
I understand the target group of 9500$USD multimeter, but still.

May be more .... What is wrong with this dude, asking US $15,600.00
http://www.ebay.com/itm/Keysight-Agilent-3458A-001-002-Digital-Multimeter-8-Digit-/141587046591?hash=item20f73ee0bf (http://www.ebay.com/itm/Keysight-Agilent-3458A-001-002-Digital-Multimeter-8-Digit-/141587046591?hash=item20f73ee0bf)

Same thing that's wrong with this guy:
http://www.ebay.com/itm/Tektronix-TDS784D-2M-2C-4C-/401003605849?hash=item5d5dad6f59 (http://www.ebay.com/itm/Tektronix-TDS784D-2M-2C-4C-/401003605849?hash=item5d5dad6f59)

Or

http://www.ebay.com/itm/MAKE-OFFER-Tektronix-TDS644A-WARRANTY-WILL-CONSIDER-ANY-OFFERS-/221180496032?hash=item337f6288a0 (http://www.ebay.com/itm/MAKE-OFFER-Tektronix-TDS644A-WARRANTY-WILL-CONSIDER-ANY-OFFERS-/221180496032?hash=item337f6288a0)

"Testequipmentexperts" should know that that scope is crap anyway... leaky caps etc.

Jay
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 07, 2015, 05:29:28 pm
macboy

No, I stolen receiver from external trigger optical link. Will put new back in after order replacement from Digikey. For now it's ok.
Title: Re: Repair : Old rusty HP 3458A
Post by: soren on October 08, 2015, 02:18:25 am
And that's correct. Only hardcore, only oldschool, using by bodge to generate UV for UVEPROM erase, so I can flash latest 9.2 firmware.

I like to use Winbond W27C512 EEPROM pulls, which are available for next to nothing on ebay/aliexpress. No need for improvised tanning beds :-)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 08, 2015, 03:52:15 am
Buying W27C512 : days of waiting
UV erase and program : 15 min
You choose :)

(http://images.tapatalk-cdn.com/15/10/07/366f3ec65b93434bac0e82ec5b9522c6.jpg)

(http://images.tapatalk-cdn.com/15/10/07/95d79f7cd6032b55ae153f008c513343.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 08, 2015, 04:27:57 am
Since ranges 1mA and more working ok, we can rule out R210,R211,R212,R213 current shunt path, as well as input relays K201,K202,K203.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/amp_diag1_1.png) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/amp_diag1.png)

It is not likely that issue to be damaged JFET switches Q201-Q205 for low-current shunts R209-R206, as it’s less probable that all of them died.
So I will test control circuitry first, which consists of U204 and U205 LM339 comparator for level shifting, U203 4094 shift register and RP200 generic resistor network and CR205 zener.
One thing we know from initial inspection – resistor network RP200 was resoldered by previous owner. I have bought RP200 replacement before, just in case, so it could come handy.

I think the most difficult in this repair would be finding DIP-packaged LM339 and LM393  :-/O I did not used DIP parts for many years, and resist urge of bodging in SO-versions in there  :blah:
I do have MC14094BCP replacement, left from Keithley 2001 repair project (https://xdevs.com/fix/kei2001/), in case I would need one.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/amp_diag2.png)

HP's CLIP listed LM339 comparator as SELECTED, what would they select in it? Offset voltage?
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on October 08, 2015, 08:49:59 am
LM339 comparator offers Open Collector outputs.
As far as I could figure out, the HPs are selected for minimum level of "OFF" output leakage and a minimum "ON" voltage (Vce).
I had so far no isues with "general" LM339, thus I believe, this was a "for security" request.
Last but not least the custom chip marking (HP number).
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 08, 2015, 09:05:44 am
I think the most difficult in this repair would be finding DIP-packaged LM339 and LM393  :-/O I did not used DIP parts for many years, and resist urge of bodging in SO-versions in there  :blah:

http://www.donberg.ie/descript/l/lm_393.htm (http://www.donberg.ie/descript/l/lm_393.htm)

http://www.donberg.ie/descript/l/lm_339n.htm (http://www.donberg.ie/descript/l/lm_339n.htm)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 08, 2015, 10:12:52 am
1 Euro for jellybean LM339? :) No, thank you, I'll keep feeding Digikey for 3.2$/10pcs and free shipping  :-+

But actually I think I'll give another chance to local electronics stores, I bet some might have LM339 in DIP with date codes from 1970's  :box:
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 08, 2015, 11:00:37 am
Ah, yes. I figured the DIP packages were now rare and just remembered donberg sells loads of old stuff (for ridiculous prices). Looks like they are easily available  :palm:
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on October 08, 2015, 11:35:16 am
In Germany they offered by Conrad @ 0.64€/pcs or @0.58€/25pcs (Conrad is not the cheapest seller)
http://www.conrad.de/ce/de/product/1253062/?gclid=CLuf5pbjssgCFUUOwwod7UQE7A&insert_kz=NA&hk=SEM&WT.srch=1&s_kwcid=AL (http://www.conrad.de/ce/de/product/1253062/?gclid=CLuf5pbjssgCFUUOwwod7UQE7A&insert_kz=NA&hk=SEM&WT.srch=1&s_kwcid=AL)!222!3!68417927961!p!!g!!lm339n&ef_id=U899gQAAAPVjv31F:20151008113105:s
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 08, 2015, 11:39:57 am
Well, I meant not that its hard to buy DIP, it was more like "I did not used dip IC for like 7 years or so". SMT rule. :)

Lets not go flamewar, but I wish all stuff be SMT, so easier to deal with..
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on October 08, 2015, 12:25:32 pm
I am a bit old fashioned and prefer DIP during evaluation & circuit testing using a pinboard.
Hate to solder just to do a quich circuit test.
But it may caused by the vintage design of myself  :'(
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on October 08, 2015, 04:41:10 pm
LM339/393 schould be easy to get in DIP. Also LM2xx / LM1xx series will do - they are the higher quality series. Chances are good, even in a small loacl shop.

DIP version might might have the advantage that you can use a socket and thus easy change, just in case they really need to be sellected.

It should be possible to follow the signal and thus localize the defect better before unsoltering parts.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 08, 2015, 07:54:30 pm
For the best of both worlds... get to solder SMT and DIP  :-+

(http://i.imgur.com/ErzSyeQ.jpg)

I think TiN was only joking about the DIP stuff, but maybe Ukranian-Taiwanese jokes in English text don't translate too well over the internet  :-DD  ;)

Now, let's get back to more interesting stuff...  :clap:
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 08, 2015, 07:59:54 pm
Agilent was using custom adapters for their A/D boards in the 3458A due to the lack of original Elantec parts.

I think TiN is passed out somewhere catching up on his sleep and the crowd is getting restless...
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 08, 2015, 08:37:07 pm
Agilent was using custom adapters for their A/D boards in the 3458A due to the lack of original Elantec parts.

I think TiN is passed out somewhere catching up on his sleep and the crowd is getting restless...
We have OldSchool for the inbetween hours... Where are you dude? Nothing in life could be more important  ;)  :popcorn:
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 08, 2015, 08:47:44 pm
I live in Florida and I am on vacation this week, so lots of time waiting for 3458A updates while working on my projects.

I agree about the importance. There is no info located anywhere else for these meters. Those that know how to repair them, have not posted any notes. It is good to see this meter get fixed and knowledge shared on its repair.

OldSchool will undoubtedly will have just as much fun with his meter.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 08, 2015, 09:41:04 pm
Nah, I did not passed out, but will soon.

5:25 AM here...

You can bet your bottom dollar, I was desperate... Look at this contraption:

I'll post more details later after some good sleep, but here's the progress tonight:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/la_test_dci_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/la_test_dci.jpg)

Dodgy 4094 which controls LM339 to control low current ranges? Testing with LA on inputs and outputs.

So I removed 4094, installed collet sockets (it's not analog critical part anyway, don't want solder board too much)..

Then decided to replace RP200 (it was soldered by prev.owner, remember?)

Removed it..

And...WTF..

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_rp200_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_rp200.jpg)

Missing pin on the bastard.. And yes, it's common pin for all 7 resistors in package to pullup LM339 output. No wonder JFETs were not working..

And since I did not have any MC14094 in DIP, but I really could not wait, used wrong sized DIP14-SMT adapter, desoldered 4094 from dead HP 33120A board, put some wiring, and...tada...:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_sr1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_sr1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_sr2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_sr2.jpg)

 :-DD

Will it work? I gave some decoupling love too with pair of 1uF 16V X7Rs

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_fix_dci_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_fix_dci.jpg)

Now my 3458A have 3 SMD components in it!

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/selftest1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/selftest1.jpg)

Bingo...

Was another issue tho, TR300 (yellow long thingy on A1 board near vishay resistors) is extremely sensitive, if I bend it just a little or touch it - ohms and current measurement go berserk and selftest failures all over it. I think bad contact inside of that thing.. So ManateeMafia's burnt board could be a handy donor, I believe.  :-X :-*

Did very rought CAL with 10V from Keithley 2400 and 10K from ESI DB52 (not even 4wire lol), passed without errors. So, almost done, perhaps?
Time to crash in bed now.  :bullshit:
Title: Re: Repair : Old rusty HP 3458A
Post by: Vgkid on October 08, 2015, 09:56:33 pm
Good Job  :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 08, 2015, 09:59:17 pm
Same here. :-+ Will have to go get some beer now...

That part looks like 10 TO-92 components connected together. Mine looks good so we can discuss later how to get that part to you.

It will be nice to see that bad part torn down but it feels like a ceramic coating. Chances of getting part numbers from those transistors could be difficult but it might be worth a future project.
Title: Re: Repair : Old rusty HP 3458A
Post by: nidlaX on October 09, 2015, 12:24:07 am
Quote
Will it work? I gave some decoupling love too with pair of 1uF 16V X7Rs

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_fix_dci_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a1_fix_dci.jpg)

Now my 3458A have 3 SMD components in it!
Holy shit! Welcome to bodge city! 8)
Title: Re: Repair : Old rusty HP 3458A
Post by: crispy_tofu on October 09, 2015, 05:29:43 am
Congratulations OP! Just a little more...  ;D
Now for OldSchoolTechCorner's 3458A repair  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on October 09, 2015, 05:36:34 am
@TiN , Great story and outcome, well done, I note those Tek clips, I am also a fan of them, they hang on like crazy and don't short to the pin next door.
You have laid down the gauntlet for OldSchoolTechCorner, I would not dare to enter this arena !!!!
Well done guys. :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: FlyingHacker on October 09, 2015, 05:48:53 am
@TiN , Great story and outcome, well done, I note those Tek clips, I am also a fan of them, they hang on like crazy and don't short to the pin next door.
You have laid down the gauntlet for OldSchoolTechCorner, I would not dare to enter this arena !!!!
Well done guys. :-+

Well done on the HP! Congrats.

Good source for those Tek clips? Are they for probes only, or general connections?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 09, 2015, 06:22:00 am
Ebay on clips (http://www.ebay.com/itm/TEKTRONIX-012-1231-02-HIGH-PERFORMANCE-LEAD-SET-W-TEST-CLIPS-JUMPER-WIRE-/271984654335?hash=item3f538c77ff). They are sorta compatible with standard 2.54mm pins, but actually they need little smaller pin thickness. I use them for everything probing around often, not just LA.

And yes, I think I missed this photo somehow.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/beer_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/beer.jpg)

ManateeMafia, we can do a teardown on that yellow thingy, no problems. Perhaps even try order ceramic PCB for replacement copy :)

Option 1 works with DS1230's after jumper JM600 relocation.
Another question, people who have real opt002, does it report OPT 0,2 for OPT? query? Yea, I know it's pointless, but still  ^-^

Title: Re: Repair : Old rusty HP 3458A
Post by: engiadina on October 09, 2015, 06:39:54 am
I am using those clips a lot:

http://de.farnell.com/hirschmann-testmeasurement/973972100/probe-clamp-2mm-60v-2a/dp/523410?CMP=os_Google-DE_ProductDetail_Redirect (http://de.farnell.com/hirschmann-testmeasurement/973972100/probe-clamp-2mm-60v-2a/dp/523410?CMP=os_Google-DE_ProductDetail_Redirect)

At least their MSRP is much lower than the TEK ones and you can find cheaper sources than Farnell.

I have the TEK clips as well, I could not say which one I prefer. Well, I might slightly prefer the TEK just because of their color. This light grey helps much better to see where the clip is connected. Apart from that, I have no preference at all. Maybe the Hirschmann are available in red or something? Have to look.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 09, 2015, 07:46:04 am
ManateeMafia, we can do a teardown on that yellow thingy, no problems. Perhaps even try order ceramic PCB for replacement copy :)

Option 1 works with DS1230's after jumper JM600 relocation.
Another question, people who have real opt002, does it report OPT 0,2 for OPT? query? Yea, I know it's pointless, but still  ^-^

TiN, congratulations for that repair!

Welcome in the club of 3458A owners..

From all we know (volt-nuts), the 3458A does not report opt. 02 automatically, as there is evidently no hardware query, and the opt 02 PCB is obviously identical to the normal version.


For the defective yellow part, you mean for sure Z300? (designator TR300 does not exist)
That is the Ohm overvoltage protection circuit.

Have a look on the 34401A, there this circuit is done with discrete transistors, 10 EA MMBT6520L.

All the HP DMMs have a very similar Ohm circuit topology, so that may be copied.
3 pins only are needed, i.e. input, output, transistor chain bias. All other are n.c.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Zucca on October 09, 2015, 07:58:34 am
He did it!

(http://blogs-images.forbes.com/jimclash/files/2014/12/ueli_steck_08-1940x1290.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: krivx on October 09, 2015, 08:41:24 am
I'm very impressed. This took you less than a month. I'm thinking about all the repair jobs I have had lingering for several years and all of them are much simpler devices than a 3458a...
Title: Re: Repair : Old rusty HP 3458A
Post by: Towger on October 09, 2015, 08:44:41 am
I'm thinking about all the repair jobs I have had lingering for several years

I am the same, but then I think of all of Dave's projects on the long finger and feel better ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 09, 2015, 09:05:54 am
Tell me about it... My own Keithley 2000 I temporarily fixed with a bodge while waiting for the correct part from Vishay sample service. I've had them sitting in a drawer for a couple of weeks meaning to get round to it, but the bodge is working and it's the AC range I don't really use so procrastination sets in...  :palm:
Title: Re: Repair : Old rusty HP 3458A
Post by: Jacek_Paw on October 09, 2015, 09:13:08 am
Option 1 works with DS1230's after jumper JM600 relocation.
Another question, people who have real opt002, does it report OPT 0,2 for OPT? query? Yea, I know it's pointless, but still  ^-^

I do have 3458A with option 002 and no, after OPT? query it displays: "OPT0,0"
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 09, 2015, 10:21:16 am
Repair of such gear is always a risky business. There is no proof that some complex fault still present, which cannot be detected by basic self-test diagnostics.
And just to prove my words, here's one. I left unit running , reading 1Meg ohms since afternoon, and when I got back just now, there is error: 114 : "SYSTEM ERROR -- multislope rundown convergence", and measurements halted.
If I press any button, it start working again and after few seconds get stuck with same error again. Any range or function.

Agilent had service note 07B for units till 2823A08000 (approximate) that says to replace A3 A/D board (and nothing else), but we don't go that road...

Quote
The delay time compensation on the A3 assembly (03458-66503 board) may cause an occasional
“Multislope Rundown Conversion” error. Design changes on this assembly have addressed this issue.
Because of the infrequent random nature of this error it is best to replace the A3 assembly and be
certain that the problem is corrected.

My unit S/N is past 08000, but who knows... I would like to know what parts are those "delay time compensation" if it's external logic..
Title: Re: Repair : Old rusty HP 3458A
Post by: EEVblog on October 09, 2015, 10:34:54 am
I am the same, but then I think of all of Dave's projects on the long finger and feel better ;)

I'm glad to be of assistance  ;D
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 09, 2015, 11:49:59 am
Cleaned board, will see tomorrow after it dry up.

Few mention this issue on web before - here (https://www.febo.com/pipermail/time-nuts/2009-August/039755.html) and here (http://www.pmelforum.com/index.php?topic=1070.0), but noone posted solution  :)
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 09, 2015, 03:34:28 pm
@Dr Frank,

Thanks for pointing that out. Looks like smd and TO-92 versions are available.

@TiN,

Good luck, hopefully a spit and polish will clean it up. I know you have seen this, but it is worth linking to this thread. https://www.eevblog.com/forum/testgear/3458a-'error-209-harware-failure-timeout-unable-to-read-ad'/msg681957/#msg681957 (https://www.eevblog.com/forum/testgear/3458a-'error-209-harware-failure-timeout-unable-to-read-ad'/msg681957/#msg681957)

At least someone had luck getting some discontinued parts for this meter.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 07:51:11 am
Nop, cleaning magic did not happen. Still doing same thing.
It does not happening if readout below 0.004, but happen for anything higher.

Checked voltages (as well as tried little higher and lower voltage, with drive from SMU) and references -12, +12, +5, they all seem to be ok and stable.
Hotair therapy with hairdryer did not change things either.

Perhaps change comparators, need find replacement part for those EL2018's..
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 10, 2015, 08:18:28 am
The hairdryer trick - you did also use freeze spray too?  :-//
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 08:20:45 am
No, i dont have that.
Hm, i old cal NVRAM in, just to try, same result.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 10, 2015, 09:11:51 am
Worth getting a can of freeze spray. When a fault shows up spray the suspects until it goes away. Hairdryer to trip the fault again (It's otherwise used to bring up a fault condition that normally doesn't show for a long time). I've fixed countless pieces of equipment with that and the "percussive maintenance" methods of fault finding intermittent stuff.  :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 09:27:48 am
Well, it shows up within seconds, so it's not like come and go.
Also I was wrong about all functions, Freq, period and AC voltage, AC current have no problem. Perhaps they not using A/D in same way?

Decided to take a break and do something else first, or I would kill something..

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/ltz_bot_cap.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/ltz_top_cap.png)

Will have 3D STEP files so folks with 3D printer could print some caps for LTZ ref's .
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 10, 2015, 10:23:27 am
But it's otherwise working for a few seconds then the fault shows up and stays? That is the number one fault mode calling for freeze spray. The hairdryer just makes the fault worse, as most semiconductor failures seem to show up when they warm up after power on. I was a bench service engineer a couple of decades back and countless faults were isolated with a can of "Freeze-it". They didn't teach me that in college so as an apprentice I would laboriously go through schematics fault finding the proper way until the old guys taught me the tricks of the trade.

Honestly just get a tin. I was just watching Daves HP1740A repair vid with loads of fault finding all the while thinking "just get the bloody freeze spray!". Sure enough he eventually tracked it to a bridge rectifier that the freeze trick would have picked up instantly. In that case the hairdryer would be used to trigger the fault first as waiting for it is boring. In your case the fault shows quickly?
Title: Re: Repair : Old rusty HP 3458A
Post by: Zucca on October 10, 2015, 10:40:37 am
Infrared Camera?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 12:01:54 pm
Caps done :) STEP and PDF. I'll have also Solidworks source in article.

top and bottom caps drawing with PDF (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/a9_cap_drw.pdf)

STEP model, bottom cap (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/a9_cap_bot.STEP)
STEP model, top cap (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/a9_cap_top.STEP)

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/ltz_top_cap.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/ltz_cap_side.png)

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/a9_cap_3d_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/a9_cap_3d.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/a9_cap_3g_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/cad/a9_cap_3g.jpg)

Title: Re: Repair : Old rusty HP 3458A
Post by: lukier on October 10, 2015, 12:54:15 pm
Great restoration. Your story was like a good drama :)

Sometimes I think I should trade my SR850 for 3458A for the sake of having 3458A :D, but then I realize that is not everyday multimeter, I would rarely use its full capabilities and all the other time I would curse  the front panel UI on this thing :)

Now, if you are seriously volt-nut, you need to carefully choose the material for your 3D print  ;D PLA will absorb moisture, deform due to heat and biodegrade. ABS might be better, but I suppose a real volt-nut would like LTZ1000 cover made of teflon or Valox like LM399 housing :)
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 10, 2015, 12:56:40 pm
Great job on the covers.

If you change the nplc settings and NDIG to something low like .01 and 4, do you still see the error? AC rundown might be more relaxed or it is input through a separate part of the A3 board for AC. Will have to look at the clip again.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 12:57:06 pm
Polypropylene would work well too, I'd believe. But since I got original caps from fellow member here, I will not go there. Heck, I don't even have 3D printer anyway :D

Issue is not present on any of AC functions (ACV/ACDCV/ACI both fine, any range), as well as freq/period. Also if I set NPLC let's say 1 or 100 on AC functions, it seem not changing, and speed is still same. Is there any other settings need to be done for AC NPLC to work?

I'll order some comparators and perhaps make that agilent-bodge from your picture in other thread.
Seems finding modern comparator with supply >18VDC and <40ns is a real next to impossible, according to my search on Linear,Digikey,MAXIM,TI :/

If I use 0.001 NPLC or faster, no error. If use 0.01 or slower, errors. Let me make a video.
I think it's because HP's ADC using only integration runup method to resolve on those speeds, and rundown used only for more precise measurements.


Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 10, 2015, 04:41:30 pm

Issue is not present on any of AC functions (ACV/ACDCV/ACI both fine, any range), as well as freq/period. Also if I set NPLC let's say 1 or 100 on AC functions, it seem not changing, and speed is still same. Is there any other settings need to be done for AC NPLC to work?

I'll order some comparators and perhaps make that agilent-bodge from your picture in other thread.
Seems finding modern comparator with supply >18VDC and <40ns is a real next to impossible, according to my search on Linear,Digikey,MAXIM,TI :/

If I use 0.001 NPLC or faster, no error. If use 0.01 or slower, errors. Let me make a video.
I think it's because HP's ADC using only integration runup method to resolve on those speeds, and rundown used only for more precise measurements.

Hi TiN,

NPLC works differently for ACV, and it also depends on the ACV mode (3 different!) used. Resolution is limited to 6.5 digits, in any case.
See manual, command reference for NPLC, p. 6-67, Remarks.

You may choose the different modes for ACV and see, if that changes something.
ACV also uses a different A/D input path (AC_AD vs. DC_AD, see CLIP).

The conversion anyhow, should or may be using the same algorithm, so maybe the problem is not with the comparators.

For faster conversions than 100us, there is a difference in the conversion algorithm, see hp journal 4/1989, p.13.
Maybe you fiddle around with the aperture parameter, and determine, when the error occurs.

Do you use ACAL frequently?
This is the most important function of this instrument, it will help, if you engage that function after your recent calibration, or after big temperature changes.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 05:32:39 pm
Thanks, I'll look into all that.
It cannot run any ACAL or selftest now, as soon as that error happens, it fails operation until i press any key on front panel. I did CAL and ACAL before when everything was working fine, and everything was booting and working without a single error or message. And ACAL is kinda pointless, as there are no covers/shields on unit anyway.

Ordered EL2018's from UTSource, as well as making order for all rest parts on DK. I ordered few ISL55143's comparators as well, can make adapter board to bodge them it. And yes, they are obsolete too, but so far available on DK.

I'll test with different mains frequency too, just too see if it would be less frequent due slower conversion speeds.

Quote
Resolution is limited to 6.5 digits, in any case.
Huh? Unexpected :D
K2002 does show all 8.5 digits. If they are meaningful, that's another story, but it does show them  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 10, 2015, 06:27:01 pm
Without trying to get anyone turned around I was thinking about U150 on the A3 board. It is listed as "Minor Slope Drivers". I have not tested it yet, but would it be possible that the minor slopes are the last few slope run downs the converter performs and that possibly the DC ranges are using it but not the AC?

I will stick a LA on the four inverter inputs and check the different ranges and modes. Hopefully, someone has been there already, but if not, I will collect some data and look for a pattern.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 06:48:49 pm
That one is ok, checked it already.

Few captures on integrator's comparator.

Left to right, NPLC 0.0001, NPLC 0.001 and NPLC 1

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/a3_signals_2_nplc0001_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/a3_signals_2_nplc0001.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/a3_signals_1_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/a3_signals_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/a3_signals_3_nplc1_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/tla/a3_signals_3_nplc1.png)

Need a scope to see anything, LA not suitable for such debug...
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 10, 2015, 07:19:01 pm
Quote
Resolution is limited to 6.5 digits, in any case.
Huh? Unexpected :D
K2002 does show all 8.5 digits. If they are meaningful, that's another story, but it does show them  :-DD

On the internal display, hp adapted the useful number of digits for each mode.

That is:
DCV: 8 1/2, DCI: 7 1/2, ACV, ACI: 6 1/2, freq/per: 7

Criterion is stability of references and of range components, noise.

Over the GPIB, up to 9 1/2 digits will be transferred.

Other 8 1/2 digits instruments like Fluke 8508A always display 8 1/2 digits, but even the specification is not appropriate for that.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 07:22:16 pm
I understand the meaning and difference behind resolution and accuracy, just interesting how different products aproached this. Low ranges on DCV also provide less digits on screen.
Title: Re: Repair : Old rusty HP 3458A
Post by: BFX on October 10, 2015, 07:25:51 pm
TiN: excellent work :-+
Thank you :-DMM

What logic analyzer you using?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 07:41:00 pm
I listed all used gear in article (https://xdevs.com/fix/hp3458a/#summary). And it's TLA714 + TLA7AA4 with P6810 probe.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 10, 2015, 08:23:52 pm
Schematics draft WIP of adapter board for EL2252CM to pop on A3.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/a3_xd1/img/adapter_a3.png)
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 10, 2015, 10:49:46 pm
I understand the meaning and difference behind resolution and accuracy, just interesting how different products aproached this. Low ranges on DCV also provide less digits on screen.

I did never doubt that!

Your zero noise project comes in handy for this aspect.

Maybe we'll finally see some people delivering figures for the KEITHLEY DMM7510 (Shahriar) and also the 8508A (quarks)??

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on October 11, 2015, 05:08:22 pm
With a fast comparator, the decoupling caps should be smaller. More like 10-100 nF on the board should be better. If really needed one might add the larger ones (e.g. 10 µf) with enough ESR (e.g. 10-50 Ohms) to damp resonances, e.g. by using electrolytics for these or with resistors and MLCCs.

To large a decoupling cap lowers the resonace too much and might gives ringing in the frequency range of interrest.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 12, 2015, 07:45:12 pm
Problem video :)

3458A Try 4 (https://www.youtube.com/watch?v=Jyx1nZHyuXs)
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on October 12, 2015, 08:29:36 pm
At high speed (low NPLC) the ADC is used in a different mode (kind of. dual slope). The same is true for AC measurements.

The message sounds like the ADC is sometimes not getting a stable state in the slow, multi slope mode.
There could be several possible defects / parts that make to ADC loop instable:
One could be a slightly too small integrating capacitor - could test with 10 % more.
Also a to large value for the larger of the integrating resistors could cause such a problem - in this case the error should depend on the voltage measured. In this case the second slower slope might take too long.
If it's a kind of analog error, more measurements of the ADC at work might help. However this might need a deep memory scope, to resolve a full conversion cycle at something like 1 PLC.

As there was some kind of mistery fix for this problem, it may be a problem that is rather difficult to locate. It took HP some time to find a fix for some kind of design flaw. So it might help of one could get the change in circuit between the old and fixed version. Worst case this is something like an updated FPGA / costum chip.

My guess is that there is something very close to the edge of just working or just not working. This might also be some kind of race condition in a digital signal.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 14, 2015, 01:46:33 am
3-4 years ago, one of the broken 3458A's I bought had a bad A3 board. Given the recent repairs and valuable info from TiN I thought I would give it another shot. All of the voltage checks were performed years ago, but I went ahead and did them again. This was a donor board as I had acquired a replacement from Agilent.

The board had a 202: Slave Test Convergence error. Based on TiN's recommendation, I went through the ZR_LO and ZR_HI inputs from the A9 reference board. Then I went through the +12ref, -12ref, and +5ref to confirm they were working.

I checked the Reset lines and clock to the 8051 (U220). That looked good.

TiN had mentioned the TARM command during his repair that I didn't previously try. Using the command, I watched the outputs of pin 6 (OUT) briefly change on U110,U111,U112, and U140. So far so good.
When I got to U142, I could see the negative transition on the input, but the output never changed from +4.2V. After testing it a couple of times, I decided to replace U142 and fired up the 3458A.

The meter came up and was reading DC. :) I ran the self-test and ACAL DC successfully.

The EL2018CN was sourced from UTSource .

Thank you TiN and all the others that have added to this thread. :-+ . Next step, repair defective A2 board with EL2039 from the same seller.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 14, 2015, 04:17:30 am
Great to read, that at least yours 3458A got progress :) Leave it running for a day or two, sampling 1Meg resistor, and perhaps it could become a lemon like mine  :rant:  :blah:

202 Error I had was due missing jumper on header near reference on A1 board. So issues we have still are different.

UTSource replied today that they will ship EL2018's soon (still did not do it so far). I'll get LM6321 buffers by friday (maybe not an issue, but one on AC A2 board run's 50ish °C.)

P.S. got DS1245YP's for scope, hope will be back in business, so I can do proper measurements and debug.

Can I add your experience into article? :) Maybe with few photos, you can practice LED lights trick ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 14, 2015, 11:18:05 am
Feel free to add it. I have more info on my A2 board, the el2039 'fixed' it, sort of. I have a missing C104 that was stolen for another board. I will find a sub and try to clean the board. The meter is reading 75V on highest range. Scal may or may not fix it. I will give it a shot once I can get a new cap. As long as I can reduce the error, I think the board will be a good enough backup. It was reading 4550 VAC before I changed the el2039.

I will see if I can capture some waveforms in trigger mode to simulate the pulses throught the chain of parts.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 14, 2015, 06:50:31 pm
Yey, my scope is back in business, after replacement of pesky NVRAM chip.

Here are some initial shots

Setup is rather crude, I'll have to make few adapters to have proper probing.
U142 EL2018 comparator output to digital domain of ADC.

NPLC 1:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U140P2_NPLC1.png) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U142_NPLC1.png)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U142_P3b.png) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U142_P3_Z.png)

It does seem to be working, at least signal is there.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U142_P3.png) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U142_P7.png)

Above two blocks of pulses, first fast ramps and then slower ramps. This is when I get measurements before error happens. Sometimes there are only first half of pulses.
Square pulse train waveform is comparator's output.

A2 Board, U504 buffer (left input pin 2, right output pin 3), meter in mV range on ACV.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U504_PIN2.png) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/U504_PIN7.png)

Looking OK.

Integrator capacitor waveform (test point TP112, left is NPLC 0.001 failing, right is NPLC 0.0001). You can see on faster setting it just takes 2 big ramps, while on slower setting it takes 12 smaller ramps.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/TP112_NPLC001.png) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/scope/TP112_NPLC0001.png)

Not sure if those little dips should be there...
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 14, 2015, 08:24:06 pm
Also on HP 3458A CLIP's schematics ADC comparator is drawn incorrectly! LM6361 U140 output going to noninverting pin 2, not 3!  :scared:

Pinout map of U180 ASIC:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/u180_pinout.png)
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 15, 2015, 12:35:16 pm
I have added some scope screenshots of my recently repaired A3 for comparison to TiN's.

The NPLC .0001 doesn't look right, but that is probably an issue with my setup.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 15, 2015, 05:47:33 pm
Thank you for measurements.

I got more parts, just to find out that Avago HFBR-2521Z is NOT pin compatible with old HP's HFBR-2501  :palm:
Got deceived by newer A3 03458-66513 board photos with HFBR-2521s  >:(
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 17, 2015, 04:55:58 pm
More followup vid's. Layout boards for adapters.

vid3 (https://www.youtube.com/watch?v=gsG3srF6sJo)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 19, 2015, 04:37:09 am
Received EL2018's from UTSources. Even tho they were listed as "New" they are not, all pins tinned and little bent.
Chips also assorted, with different datecodes, from 1991 to 2000. Hope ones I pick would work and fix pesky error.
Better be, If not I'll use hammer for non-authorized express repair of evil thing...  :scared:

I wonder how's OldSchoolTechCorner doing? He's been suspiciously quiet for long time  :-/O :-X
Title: Re: Repair : Old rusty HP 3458A
Post by: crispy_tofu on October 19, 2015, 04:55:07 am
I wonder how's OldSchoolTechCorner doing? He's been suspiciously quiet for long time  :-/O :-X

Same, waiting very impatiently for a repair!  :-/O :popcorn:
Title: Re: Repair : Old rusty HP 3458A
Post by: Mickle T. on October 19, 2015, 06:47:35 am
"114 SYSTEM ERROR - balanced rundown convergence"
http://bbs.38hot.net/forum.php?mod=viewthread&tid=134921 (http://bbs.38hot.net/forum.php?mod=viewthread&tid=134921)
Title: Re: Repair : Old rusty HP 3458A
Post by: crispy_tofu on October 19, 2015, 07:46:50 am
I may be interpreting this wrong (lol Google Translate), but the forum post is saying to replace the AD637 (U601).

Never mind, unrelated.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 19, 2015, 08:35:19 am
They are for a fault in the AC section which TiN isn't having trouble with.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 19, 2015, 10:05:39 am
Unless fault on AC board cause somehow problems on DC. Time to try those EL2018's.  :box:
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 19, 2015, 10:32:04 am
Unless fault on AC board cause somehow problems on DC. Time to try those EL2018's.  :box:

What's interesting about the failure in the AC path, it is not related to the A/D section, and especially not to the comparators.
The signal from the AC simply is not responding, and that causes this error message.

If you think this idea a bit further, maybe the DC path before the A/D input is broken or unstable somewhere ..
So, before changing the EL2018, which seem to be operable, as AC is digitized correctly, I would first give this DC path a try.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 19, 2015, 04:54:34 pm
Well, seems something might be true in that. If I disconnect DC_AD from A1 board, I can run longer till error come, even like 5 minutes using NPLC 0.5.

Balanced error almost gone after replacement of all three EL2018 on A3. I'll more into A1 and A3. Looking on schematic, A3 also have DC function blocks, it's not AC only board there.

I was also scoping around and noted big spikes on DC_AD signal with repetive digitazing rate, like 30V peak peak, from negative to positive rail. I wonder if that normal. Tried autozero off and on, same result.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 19, 2015, 05:03:52 pm
I found this in Chapter 4 of the service manual pg 72 (03458-90011)

"The AC circuitry is also used for track/hold measurements.  Although these
measurements are DC volts measurements, the AC circuitry is used due to
its higher bandwidth.  Track/hold requires a higher bandwidth than the DC
circuitry provides."
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 20, 2015, 10:50:10 am

I was also scoping around and noted big spikes on DC_AD signal with repetive digitazing rate, like 30V peak peak, from negative to positive rail. I wonder if that normal. Tried autozero off and on, same result.

Strange thing. Sure that this doesn't come from outside? (Probably no)

Just an idea, about what has been changed essentially: Did you connect the shields of the transformer in the correct manner?
No ground loop from Dig to Ana PSU?

Btw.: Thank you very much for the schematics of the transformer!

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 20, 2015, 11:35:03 am
Yea, tried either way. What puzzles me, that meter was working ok for a day before it failed...
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on October 20, 2015, 06:02:04 pm
There should not be such large spikes. If at all something in the low mV range (so hardly visible on the scope) may be.

Teh delayed problem may be due to a hidden defect that inititially (e.g. cold) did no big harm but than did some damage somewhere else. Its well possible that such excessive spikes can damage some other part - up to the point of causing a latchup in some chips. So we likely look for more than one defect part. Those parts that where allready fixed (possibly by someone else before) are prime candidates to look for - not as the prime source of damage, but as a damaged part.

Finding the source of these spikes would be likely the first step.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 20, 2015, 07:04:20 pm
Also I think it's worth to leave link to this patent (http://www.google.com/patents/US4922130), explaining exactly 3458A's track&hold circuitry. Question if it's being used for DC measurements is remain to be seen.

Brute force repair is not going to work this time, so need actually sit and learn how DC path in instrument working. To compare - i already spent more time on this Error 114 issue than whole rest repair project total (over 40 hours). Good example of how initial "easy" repair can go bad in no time.

Where is our second sunken 3458A owner. Reveal youself :)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 21, 2015, 05:42:33 pm
Captured bunch of diagrams on A1 board.
http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/scope_data/ (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/scope_data/)

U107 2.5V REF output is somewhat -16.11V. Based on schematic, I don't see how that is correct.
Perhaps I can get reference measurement to check on this one..
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on October 21, 2015, 08:07:17 pm
I can check that in a couple hours.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 21, 2015, 08:40:24 pm
Captured bunch of diagrams on A1 board.
http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/scope_data/ (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/scope_data/)

U107 2.5V REF output is somewhat -16.11V. Based on schematic, I don't see how that is correct.
Perhaps I can get reference measurement to check on this one..

Without knowing that chip, I assume that this circuit part is referenced to -18V, not to GND:

That seem to create a CC for the input amplifier, i.e. constant 2.5V over R103 => 1.4mA

You should measure constant 2.5V between -18V supply (pin3 of U107) and output, pin2.

Or your -18V should read about -18.6V

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 22, 2015, 12:39:32 am
Doh, sure you right. Should have noticed minus sign on voltage rail there. No problem there.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 26, 2015, 04:20:17 am
Just a heads up. No progress was archieved so far, was back to A3 A/D board replacing more parts without any improvement:

So far replaced U142,U181,U170(to LT1013), U230, U303, U304, U110, U112, U150, U400, Q403, CR405, CR406, CR111, added OSCON capacitors around C122,C120,C181 for sake of trying, no any sign of improvement, it still does fail with Error 144 - multislope rundown convergence or Error 114 - balanced rundown convergence.

There are not much components left to try, and it could be suspected unobtanium suspect ASIC U180, which handles all charge mangment around integration and switching.

I'm pretty sure it's not A2 or A1 board, as I had excluded them from analog DC path and still was getting same issue (used my LTZ1000 reference module externally, disconnected AC_AD and shorted DC_AD to ground on A3 PCB).

It's possible we have to go plan B in this case...  :-X
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 26, 2015, 08:47:57 am
Just a heads up. No progress was archieved so far, was back to A3 A/D board replacing more parts without any improvement:

So far replaced U142,U181,U170(to LT1013), U230, U303, U304, U110, U112, U150, U400, Q403, CR405, CR406, CR111, added OSCON capacitors around C122,C120,C181 for sake of trying, no any sign of improvement, it still does fail with Error 144 - multislope rundown convergence or Error 114 - balanced rundown convergence.

There are not much components left to try, and it could be suspected unobtanium suspect ASIC U180, which handles all charge mangment around integration and switching.

I'm pretty sure it's not A2 or A1 board, as I had excluded them from analog DC path and still was getting same issue (used my LTZ1000 reference module externally, disconnected AC_AD and shorted DC_AD to ground on A3 PCB).

It's possible we have to go plan B in this case...  :-X

Ok, before you replace further components, especially U180, maybe it's possible to test a bit further.

I was under the impression, that the instrument maybe stuck itself into this failure mode, by improper ACAL (?) calibration constants.

Maybe you bring the instrument back to some initial state first.


I assume, that you stored the content of the CAL nvRAM (2kx8).
And you may also have the old DALLAS parts, which you may erase to FF in all cells on your ext. programmer, and then insert into the instrument.
(Store the new nvRAM in a safe place)

Also, please remove these 4x 32kx8 additional RAM, U123-U126, as you used nvRAMs also, which may  confuse the instrument on booting.
Maybe, you might also erase the other both 32kx8 nvRAMs to delete all possible stored states.

If you then start the instrument, you will have a virgin state, causing many CAL and ACAL errors.
The FW will initialize all calibration constant to a default, and an initial ACAL will be necessary.
On 2nd boot up, there should be no error any more, provided, the old nvRAMs still work.
(Otherwise you'd have to use the new nvRAMs for that)

Maybe, this may cure the problem.



In case there's no success, you might first measure precisely the +/-12V and +5V ADC references, TP160, 165, 151, for correct ratio (1.69x) relative to LTZ value, and for stability.
(If there's a noteworthy deviation, that may also cause your error).

I'm not sure, if the Time Interpolator is used for normal DCV operation (to my opinion, only in Digitizing Mode, like ACV Sub- and Random Sampled)
But who knows.. Inside there's another EL2018, U405, maybe you check this IC also.

These convergence errors have not yet been understood well in the past (for other instruments).. but this might have to do with the matching of the different slope resistors , as described in hph4/1989, page 12. It's necessary, that the absolute values of these internal resistors fit each other, not extremely precisely, 0.1% only.
They cannot be accessed externally, that's the problem.. But maybe you try carefully to measure the 50k between pin 6 and pin 11/13 of U180, and maybe the minor slope resistors, pins 18,19,21,23.

And you also did not leave any fingerprints there, I assume, which may cause parasitic currents at the A/D.

Give all that a try before giving up ..

Good luck

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 26, 2015, 01:32:13 pm
Quote
I was under the impression, that the instrument maybe stuck itself into this failure mode, by improper ACAL (?) calibration constants.

Does not look like that. It did run SELFTEST fine about 5 times I did, then passed complete ACAL on all functions, then I did CAL against 10V from K2400 SMU and against 10K resistor from ESI DB52.
Turn meter off, turn meter on, measured 10V from K2400, values matches, all okie, run SELFTEST couple more times, turn off unit.

Next day - power it back on, measured 10V, all ok, connected 1Meg VPG resistor and leave it sampling NPLC 10, all settings default. Was fine for at least 30 minutes, then I left room, come back in 5 hours - measurements halted, ERR message 114. Since then it's all the same, throwing these two errors on anything >100us conversion time on all ranges/modes in DCV,DCI,Ohms, no matter what other settings I fiddle with. Sometimes can do 3-5 samples at NPLC 10, sometimes cannot do even 1 count on NPLC 0.01. Usually locks up less the a second.

Quote
I assume, that you stored the content of the CAL nvRAM (2kx8).
And you may also have the old DALLAS parts, which you may erase to FF in all cells on your ext. programmer, and then insert into the instrument.
(Store the new nvRAM in a safe place)

Tried all that, no effect. New NVRAMs, old NVRAMs, erased, or in original state, all same. Just tried once again, same. I'd assume digital outguard domain working OK at this point.

Quote
Also, please remove these 4x 32kx8 additional RAM, U123-U126, as you used nvRAMs also, which may  confuse the instrument on booting.
Maybe, you might also erase the other both 32kx8 nvRAMs to delete all possible stored states.

No effect, just did this, and tried this week ago. Regarding CAL ROM, I tried that (just poped in old NVRAM chip, which still have original data), no difference.

Quote
If you then start the instrument, you will have a virgin state, causing many CAL and ACAL errors. The FW will initialize all calibration constant to a default, and an initial ACAL will be necessary.
On 2nd boot up, there should be no error any more, provided, the old nvRAMs still work. (Otherwise you'd have to use the new nvRAMs for that)

Old SRAMs dead, but as all above, I don't think there is a problem. Yea, I even tried to run without CAL NVRAM, believe me. On this matter meter tells you to change jumper JP132 and power cycle :D.

Quote
Maybe, this may cure the problem.

Nope, no magic pill on A5 board :).

Even removed all ROM chips and checked them to make sure all data verified 100% match to firmware binaries. (I had unit running open cover those two days when it covered, was thinking maybe bit or two got corrupted from sunlight UV. Nope all were 100% match.)

Quote
In case there's no success, you might first measure precisely the +/-12V and +5V ADC references, TP160, 165, 151, for correct ratio (1.69x) relative to LTZ value, and for stability.
(If there's a noteworthy deviation, that may also cause your error).

Now we have something.

ZR_HI to ZR_LO (entrance of zener voltage from A1, at A3 connector): +7.07411, stable up to 5th digit.
ZR_LO to TP160 (+12VREF) : +11.93936 V, stable to 5th digit. Ratio to LTZ is 1.687754
ZR_LO to TP165 (-12VREF) : -11.92274 V, stable to 5th digit. Ratio to LTZ is -1.685404
ZR_LO to TP151 (+5VREF)  : +4.960405 V, stable to 5th digit. Ratio to LTZ is 0.701205

Also probed with scope, did not see any spurious large-scale noise.

Quote
I'm not sure, if the Time Interpolator is used for normal DCV operation (to my opinion, only in Digitizing Mode, like ACV Sub- and Random Sampled)
But who knows.. Inside there's another EL2018, U405, maybe you check this IC also.

Replaced U405 as well, forgot to mention, sorry. I have now both U142 and U405 with collet sockets, tried bunch EL2018, none show any difference.

Quote
These convergence errors have not yet been understood well in the past (for other instruments).. but this might have to do with the matching of the different slope resistors , as described in hph4/1989, page 12. It's necessary, that the absolute values of these internal resistors fit each other, not extremely precisely, 0.1% only.
They cannot be accessed externally, that's the problem.. But maybe you try carefully to measure the 50k between pin 6 and pin 11/13 of U180, and maybe the minor slope resistors, pins 18,19,21,23.

50K network read as 50.2095 kOhm. Added pair of 22M RN7C resistors between pin 6 and pin 28 - got 49.982K, still same behaviour.

I tried to measure minor resistors, got wrong values, but that's likely to opamps in loop. Only way is to desolder U180 and measure separately.

Quote
And you also did not leave any fingerprints there, I assume, which may cause parasitic currents at the A/D.

Yep, leakage are bad in low-current charge balanced circuit, but cleaned multiple times, IPA, distilled medical grade water, IPA again, no any visible difference.

Quote
Give all that a try before giving up ..

Nobody is giving up so easily, just more radical, less enjoyable approach would be taken :)

I also reflowed pins on U180, no effect (just heated up joints to solder point, without removing chip)

I also tried voltage margining on all supply rails (+5, +18, -18) and voltage references (-12, +12, +5) one at a time, injecting little current with SMU into feedback nets, did not see difference, so it's not like something is bit off tolerance, talking about voltage domain. Problem likely lies in current domain or in timing/sequencing.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 26, 2015, 02:21:04 pm
(http://uk.farnell.com/productimages/large/en_GB/42419271.jpg)

..erm... did you try?? Give suspects like U180 a blast then switch on and see how long before errors.  :-[

( ...goes and hides from TiN's ire, frustration and rage! )  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 26, 2015, 02:39:24 pm
I cooled it (U180) to 0°C with 40x40mm TEC while running, nope :)
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 26, 2015, 02:49:16 pm
Another odd idea, analogously to the AC converter error in the bbs38hot thread:

Have you ever re-aligned the jumper P100, located near the LTZ assembly,which initially was missing? (see picture)
What happens, if you set this to OV, 7V, back to normal?

Is the signal out of U100 stable?

(I know, that you already fed DC signal directly into DC_AD, I assume)

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 26, 2015, 03:10:45 pm
I cooled it (U180) to 0°C with 40x40mm TEC while running, nope :)

Oooh.. Get you! Even your thermal diagnostic tricks are an another level!  ;)

I tell you what, I wish OldSchool' didn't have to flog his old Riglent gear to try and raise funds for his 3458A restoration. He could be joining in right now.

Hmm... Seeing as he's busy with all that legal shenanigans, maybe he would be a gentleman and lend you his ADC board for comparison purposes?  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 26, 2015, 03:55:45 pm
Macbeth
So we end up having not one, but two meters broken? Nah :D
Feel bad for OldSchool, that's nasty bork on his ebay acc.  ???

Dr.Frank

Same stuff, meter just reads near zero if P100 set to GND or 7V, but conversions are still locking up with E114.
That's why I'm not taking A1 into account.

I might have another piece of gear to come (not 3458A, but HP-made too), so feel like kinda failed on this project.
I spent less than 30 hours on all repairs total, and wasted already over 60 hours on this A/D convergence stuff  [emoji14]alm:. Eek..  :bullshit:
Title: Re: Repair : Old rusty HP 3458A
Post by: MadTux on October 27, 2015, 07:06:17 pm
Have you considered cleaning the boards?

That faults seems so typical for electronics with water damage. Everything seems nice and dry and the instrument is powered on. But there is still some salts or water in some hidden spot. This water is then electrolysed into hydrogen and oxygen, that causes corrosion damage. Salt residues might be hygroscopic and draw water from atmosphere and also cause increased leakage. Then after a while the instrument fails without clear evidence of a failed component (shorted tantalum capacitor, dried electrolytic or obvious failed components somewhere like a bad transistor or diode that shifts all voltages related to it or shorts something out) because of leakage or corrosion damage somewhere.

I would guess that the previous owner(s) quickly flushed the boards with (deionised) water to prevent most of the damage that the frame received from long time water exposure but didn't dry it well afterwards. Then when the faults shown on ebay became evident, they trashed it.

 So before declaring the project as failed, I would consider cleaning all critical boards with normal water/soap, blow dry with compressed air from compressor (something like that: http://www.honestraders.com/images/air-compressor/2.jpg (http://www.honestraders.com/images/air-compressor/2.jpg) compressed air cans are crap), flush with deionised water, dry again and then optionally flush again with isopropyl alcohol. I cleaned lots of boards that way, even dishwashered a dirty 3456A analog board and they all work fine so far.

Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 27, 2015, 07:14:41 pm
Have you considered cleaning the boards?
I do believe TiN has a plan B. I also believe (considering the lengths he has gone so far and his amazing efforts to reverse engineer the 2001 PCB) that this will involve not just that but also desoldering every damn component on the board and testing out of circuit! Then scrubbing up the PCB. In fact - why not make a whole new one? Only double sided...  :-DD Keep some in stock to sell on...  :popcorn:
Title: Re: Repair : Old rusty HP 3458A
Post by: Mickle T. on October 28, 2015, 06:10:23 am
 :)
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on October 28, 2015, 06:48:11 am
@ Mickle T, You are mad  ^-^
Title: Re: Repair : Old rusty HP 3458A
Post by: crispy_tofu on October 28, 2015, 06:50:18 am
:)

T...th...that's not soapy water, is it?  :scared: :scared:
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on October 28, 2015, 11:49:27 pm
Several 3458A's were just listed on ebay - several with errors. Anyone else want to give a repair effort a go? The one for 2199 with error 209 might be a decent option.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on October 29, 2015, 03:35:37 am
I cooled it (U180) to 0°C with 40x40mm TEC while running, nope :)

Oooh.. Get you! Even your thermal diagnostic tricks are an another level!  ;)

I tell you what, I wish OldSchool' didn't have to flog his old Riglent gear to try and raise funds for his 3458A restoration. He could be joining in right now.

Hmm... Seeing as he's busy with all that legal shenanigans, maybe he would be a gentleman and lend you his ADC board for comparison purposes?  ;)

I ended up upgrading to new much faster mixed signal scope, plus a better signal generator and reason sold the Riglent gear, which I would have never expect what they did, at least they made it right, just hope they won't do it again.     

Could lend you the ADC board if you need it for the time being, since I have to finish up other projects I have on the bench currently before starting the 3458A restoration.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 29, 2015, 04:09:59 am
No need man, glad you got upgrade and sorted out selling adventures. I have something coming already, to fix my 3548.

I also got another piece of HP gear , which worth own restoration thread.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on October 29, 2015, 04:24:46 am
No need man, glad you got upgrade and sorted out selling adventures. I have something coming already, to fix my 3548.

I also got another piece of HP gear , which worth own restoration thread.

Wonder what the next piece of HP gear will be? >:D
Title: Re: Repair : Old rusty HP 3458A
Post by: helius on October 29, 2015, 04:57:41 am
Thanks TiN for the repair log, very interesting and helpful.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap1.jpg)
Oh-ho-ho. Glad I removed them. And glad HP 3458A using only 2-layer PCBs, so I'll just clean it to shiny copper, add thermal-resistant mylar cover around pins , just in case.
How do you decide when the PCB needs to be scrubbed down to copper, and how wide to go?
I have some 4-layer boards with NiCad leak damage, in some cases there is visible darkening around the PTH that can be seen through the board. If there are no traces in the darkened area, would it work to simply mill it out?
Title: Re: Repair : Old rusty HP 3458A
Post by: krivx on October 29, 2015, 08:51:19 am
Thanks TiN for the repair log, very interesting and helpful.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a6_cap1.jpg)
Oh-ho-ho. Glad I removed them. And glad HP 3458A using only 2-layer PCBs, so I'll just clean it to shiny copper, add thermal-resistant mylar cover around pins , just in case.
How do you decide when the PCB needs to be scrubbed down to copper, and how wide to go?
I have some 4-layer boards with NiCad leak damage, in some cases there is visible darkening around the PTH that can be seen through the board. If there are no traces in the darkened area, would it work to simply mill it out?

I would mask out the area and go to town with fiberglass brush. See if you can clean it once the soldermask is removed.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 29, 2015, 03:07:42 pm
helius

Well, think about end result you want to get. Task is to try remove all electrolyte from PCB surface, so it would not cause more damage than it already did.
In this case it was simple as PCB is only dual layer, and pin hole is really big and sturdy, not like those tiny 20 mil vias on 8-layer PCBs.

Removing solder mask to good unaffected zone is just a measure to guarantee that electrolyte soaked in between copper and mask effectively removed and cleaned off.

If you have multilayer via oxidized, I usually clean everything on top and bottom surfaces, get via pad surface to shiny tin/copper and then clean it's drill hole with thin strand of wire and solder in jumpwire inside affected via, so I would not have to worry about bad connection (in case of internal via's barrel got eaten away). It takes some time to do, but it's the way to save yourself from debugging random rare intermittent issues.
Title: Re: Repair : Old rusty HP 3458A
Post by: helius on October 29, 2015, 07:00:21 pm
then clean it's drill hole with thin strand of wire and solder in jumpwire inside affected via, so I would not have to worry about bad connection (in case of internal via's barrel got eaten away).
Thanks. If I understand you correctly, you mean use a patch wire inside the hole to connect the component lead to its net, because the plating could be bad. But if the PTH has an internal layer connection that has corroded, you need to find another point to connect the wire to?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 03, 2015, 10:04:52 pm
Christmas time here.

Received few boxes of goodies today, one of which contained A3 PCBA.
Replaced A/D board in 3458A, and as you expected, it worked just fine. There was another fault - 204 : Level DAC Convergence, but that was due to dodgy EL2018 comparator on A2 AC board. After it's replacement - Self test PASS, calibration 0 passed, calibration 10V passed, calibration 10K passed.

Meter is assembled with shields and covers, I'll leave it running 24/7 to see if any other issues pop-up.

I also pimped up my A9 LTZ1000A reference to reduce temperature, prior to calibration:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_mod1_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_mod1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_mod2_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_mod2.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_mod3_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a9_mod3.jpg)

Fancy 0.3ppm/K VHP101 custom-aged 95K000 resistor used on R114 location.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 03, 2015, 10:46:40 pm
3458A vid (https://www.youtube.com/watch?v=QPz6caGhYhU)
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 03, 2015, 11:28:22 pm
Fingers crossed, that it works now!

Additional cost for the A/D board..

Would be interesting to find out about ERR 114, ..convergence.. if that is related to the ASIC, then 3458A with error of that kind all need new board, not only the EL2018..

Hope, that you will now finally be in the club by tomorrow!
Was a real pain to see you suffering with these failures..

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 03, 2015, 11:44:06 pm
When this new board does work hopefully you will have another stab at finding what was wrong with the old one, e.g. swap U108 over. If that fixes it then try this new board with the old U108 (or whatever suspect) to make extra sure its just that part alone and not some mix of components all conspiring against you.  :-DD

If it's not an unobtanium part then maybe you can at least recoup some cost by fixing the old board. Besides, it's component level repairs I like to see, not board swapping  :-+  ;)

Good to see you got a partner for it with the 3245A. Are you turning into a HP fanboy now? Poor Keithley... :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 04, 2015, 12:08:02 am
I also have an A3 with the same 114 error. It originally was considered a good spare but ...  This is not the same A3 where the El2018 fixed the problem of no readings from the board.

 I have put off diagnosing it for a few days while working on other projects. I can confirm that temperature is a factor. It takes 30+ minutes for the first error then it consistently throws errors every couple of seconds with all covers on. With the covers removed, it will error once or twice an hour.

Cooling spray will be difficult due to the infrequent errors with it open. My thought is to set my hot air station to its lowest temperature and apply heat for a couple of seconds. My concern is the temperature may be 100C or higher.

I have confirmed that all voltages are good except for the LM358 (U170) is being fed ~ -16.8vdc. The datasheets list 16v as an abs max supply voltage for this IC. I have not replaced any parts yet but it was received without one of the EL2018's. I installed one but as expected, the error did not change.

If you have any tests to run, let me know. It would be great to find at least one cause for this error outside of U180.

Of course, I can use Macbeth's suggestion and swap the U180's with a good board.

The plan is to test it this weekend barring any changes in my work schedule.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 04, 2015, 12:57:40 am
You can call me chicken, but I'm not even looking on new board, leave alone swapping something on it, lol :)

Will have another peek on old board some-when in future, when get new ideas, but not involving new board. I have few ideas to try, but need finish all other projects which delayed due 3458A too .
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 04, 2015, 04:20:44 am
Are you turning into a HP fanboy now? Poor Keithley... :-DD

I still have more Keithley's than HP's. Let's see. Four 2001's, one 182M, one 2400, one 2002, one 2000, one 2510, parted 7001 against HP 33120, 4263B, 3245A, 3458A. K wins.

All HP gear is calibrated against my Keithley 2001 (which was cal'd by Tektronix in Feb/2014). :) After few months of running 3458A (hopefully, issue-free), I'll get some confidence and will take 3458A to local metrology institution to calibrate against JJA. After than unit will be sealed permanently and will be used as primary 24/7/365 realtime online monitoring for voltage reference bank.  :-DMM.
At least, that's the plan for nearest future.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 05, 2015, 12:28:21 am
This morning is sunny here, ambient temperature raised up to +30°C, meter internal temperature read +39.7°C, sampling 10V at NPLC 50, no problems second day.  :popcorn:
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 05, 2015, 10:13:17 am
This morning is sunny here, ambient temperature raised up to +30°C, meter internal temperature read +39.7°C, sampling 10V at NPLC 50, no problems second day.  :popcorn:

 :-+ :-+ :-+

With the original fan, and a cleaned filter, the interior heats up 13°C above ambient, instrument sitting free on table top.

Yours only rises 10°C.
Did you install a stronger fan than the original one?

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 05, 2015, 10:31:45 am
I got same rating fan, but not exactly same model/vendor, so it might be bit stronger with overdrive at +15V. I think I listed exact fan Digikey P/N before.

Or your fan become old and dropped it's speed perhaps :D

EDIT: I don't have fan filter installed atm, that's probably why..  :-DD

P.s. still good, running EZGPIB script to capture short DCV noise :)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 05, 2015, 05:36:23 pm
Tested noise with simple AWG26 copper wire short. Still running script for faster NPLC's.
Added ManateeMafia's data from July 2015 on his 3458A for reference (red lines on graph).

This is standard deviation data, not RMS values.

100mV range. I wonder what's up with that dip at NPLC 50 and slower.

(http://xdevs.com/datashort/_done/c100mv.png)

1VDC range, same dip.

(http://xdevs.com/datashort/_done/c1v.png)

10VDC base range

(http://xdevs.com/datashort/_done/c10v.png)

100VDC

(http://xdevs.com/datashort/_done/c100v.png)

1KV range

(http://xdevs.com/datashort/_done/c1000v.png)
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 05, 2015, 08:59:14 pm
The increasing noise at more than 50 NPLC likely come from something like 1/f noise. This could be directly from the FETs or due to thermal effects. If no auto zero is used this would be some kind of slow drift that get visible. If Auto zero is used, it is just too long in between.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 06, 2015, 04:05:51 am
1/f noise? Why other unit is not showing it then?  :)
Title: Re: Repair : Old rusty HP 3458A
Post by: Jay_Diddy_B on November 06, 2015, 04:29:52 am
Hi,

Is your unit open?

You may need to shield (the reference) from air currents??

Regards,

Jay_Diddy_B

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 06, 2015, 04:44:46 am
No, everything is assembled and closed, as it should be.
Title: Re: Repair : Old rusty HP 3458A
Post by: OldSchoolTechCorner on November 06, 2015, 06:03:30 am
You can call me chicken, but I'm not even looking on new board, leave alone swapping something on it, lol :)

Will have another peek on old board some-when in future, when get new ideas, but not involving new board. I have few ideas to try, but need finish all other projects which delayed due 3458A too .

Curious to see what failed on that A/D board.
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 06, 2015, 09:47:38 am
LF noise due to thermal effects (much of this depends on local  thermal drift) and 1/f noise of JFETs are not the same on all units. Some may be better than others.

As the effect is larger in the low voltage ranges, this is very likely an effct of the input amplifier or input circuit, definitely not from the reference voltage.

In many applications one can get around this, by using the instrument at something like 10-50 PLC and do averaging after this. 
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 06, 2015, 12:22:55 pm
It might be different amount of samples. I had 10 minutes sample window, while reference data is 30 minute sample window. Should not impact so much though.
I also ran other NPLCs, including fast ones, note step when A/D changes slew rate just at 0.006 NPLC (100us), following graph in HP 1989 Journal  ^-^

Also 200NPLC point not following 1/f noise theory...

(http://xdevs.com/datashort/_done/d10v.png)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 06, 2015, 05:33:00 pm
Few photos I forgot to post before:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_top.jpg)

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_bot.jpg)

I did replace front/rear switch, as original one had missing locking spring to keep position. Also who knows how good were original contacts....

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_sw_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_sw.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_swr_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a10_swr.jpg)

New switch was ordered from Keysight, 55$.

Now meter is sampling AD584KH 10V output with NPLC 200 using Raspberry Pi + Python script:

Code: [Select]
# xDevs.com Python test GPIB app
# http://xdevs.com/guide/ni_gpib_rpi/
import sys
import Gpib
import time

with open('10v.csv', 'a') as o:

    inst = Gpib.Gpib(0,1) # Instrument GPIB Address = 17
    inst.clear()
    #inst.write("*CLR")
    inst.write("PRESET NORM")
    inst.write("OFORMAT ASCII")
    #inst.write("BEEP")
    inst.write("DCV 10")
    inst.write("TARM HOLD")
    inst.write("TRIG AUTO")
    inst.write("NPLC 200")
    inst.write("NRDGS 1,AUTO")
    inst.write("MEM OFF")
    inst.write("END ALWAYS")
    inst.write("NDIG 9")
    inst.write("DISP MSG,\"                 \"")
    inst.write("DISP ON")
    #data = inst.read()
    #print data
    o.write("date;hp3458a;data;\r\n")

    min = 0
    while min <= 10000000:
        min+=1
        inst.write("TARM SGL,1")
        data = inst.read()
        time.sleep(5)
        print time.strftime("%d/%m/%Y-%H:%M:%S;") + ("[%8d]: %9.8f" % (min, float(data) ) )
        o.write (time.strftime("%d/%m/%Y-%H:%M:%S;") + ("%d;%9.8f;\r\n" % (min, float(data) ) ))

Good idea to use DISP MSG command to output empty spaces, so you will not kill VFD too quick when running long data capture sessions. Only problem, bottom line like "SMPL", "MRNG" segments still lit. DISP OFF command disables them, but it outputs "-------" dashes on main line instead  :palm:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/gpib_xdevs_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/gpib_xdevs.jpg)

I'll be out of town this weekend, so meter will be left on, running this piece of code for 2 days.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 06, 2015, 06:20:28 pm
Maybe a peek inside the ROM code will show where the dashes are and a hack to replace them with spaces can be made.
Title: Re: Repair : Old rusty HP 3458A
Post by: Jwalling on November 06, 2015, 06:34:04 pm
Maybe a peek inside the ROM code will show where the dashes are and a hack to replace them with spaces can be made.

Couldn't that screw up the checksum so it will fail self test? I suppose it could be possible to make a change elsewhere to compensate...
Jay
Title: Re: Repair : Old rusty HP 3458A
Post by: PA0PBZ on November 06, 2015, 07:50:23 pm
Maybe a peek inside the ROM code will show where the dashes are and a hack to replace them with spaces can be made.

They probably do:
Code: [Select]
dash = 16
while dash > 0
output '-'
dash--
wend

so it would be hard to find...
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 07, 2015, 03:17:18 am
Maybe a peek inside the ROM code will show where the dashes are and a hack to replace them with spaces can be made.

They probably do:
Code: [Select]
dash = 16
while dash > 0
output '-'
dash--
wend

so it would be hard to find...


I did a quick search and found two instances of 16 dashes in the ROM (Rev 9)

Couldn't that screw up the checksum so it will fail self test? I suppose it could be possible to make a change elsewhere to compensate...
Jay

Definitely yes as the system has error codes for ROM checksum. Looking through the code I could not easily determine where the checksum is stored. Presumably it is contained in the last several bytes of the file (last several non FF bytes).

Is it worth the effort? Maybe not, but it might be an option once the 3458A is discontinued and replacement displays become unobtanium.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 09, 2015, 12:00:25 pm
I'll look into firmware, should be rather easy to hack into.

Meanwhile, ran script to capture noise on short ppm/range once again, this time with 30minute sample window and LFILTER ON.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/comp_3458a.png)

Much closer to MM's 3458A, but still away from Dr.Frank (his results not using scripts, nor autozero, also no NPLC1000).

One thing I noted from reading manual that actual NPLC >10 is not increasing integration time, but just doing averaging of NPLC10 samples. There is other way to set speed, using APER command, with maximum integration time as 1 second. Should try that.

Running now without autozero, 5min window. No errors from meter so far.  :-+

If anyone with 3458A want to jump in, just get this EZGPIB script (https://xdevs.com/datashort/EZGPIB_Scripts/ver1.01/HP3458A_Measure_DMM_Noise_Ver1.01.zip) and EZGPIB itself (https://xdevs.com/datashort/EZGPIB_Scripts/EZGPIB.zip). It takes 17 hours to complete run on all ranges/NPLCs. It can be quicker if reduce window

Code: [Select]
const duration=30;                // Acquisition time in minutes / cycle

Final internal view on both sides of meter before shields installed:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_top_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_top.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_bot_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_bot.jpg)

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_face_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_face.jpg)

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_back_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_back.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 10, 2015, 08:23:11 am
@TiN, MM and Dr F, I think you have a lot to answer for ! (HiHi)
I have just bought a 3458A that needs a little love (1 Fault = RAM Test Low) for a reasonable "Australian" price (in Australia at present everything is really expensive for us, so a good place for you guys to visit for a holiday). I have a lot to read about memory management in general and about a 3458A. If I get stuck I may ask for some help but it may take me some time - i.e. weeks (in between pesky but paying day job) to get my head around these issues :-DMM
Title: Re: Repair : Old rusty HP 3458A
Post by: crispy_tofu on November 10, 2015, 09:33:27 am
Congrats on the purchase!! :clap:
Title: Re: Repair : Old rusty HP 3458A
Post by: Monittosan on November 10, 2015, 10:48:02 am
I think I'm going to have to get another 3458A after today  :)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 10, 2015, 10:50:13 am
Get your pocketses ready to be emptied :)
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 10, 2015, 11:00:53 am
Thanks CrispyT, I am aware I am not in the league of TiN, Dr F and the others so I will do a lot of reading/testing before I do anything!
Starting from re reading this thread!
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 10, 2015, 11:09:38 am
Fixing RAM is fairly easy. You can get more details from my worklog (http://xdevs.com/fix/hp3458a/). Use solder sucker or wick to release original NVRAM pins and solder collet-type socket instead. You can try your luck with Maxim samples for DS1230 (U need two) and DS1220 (need one).

Save calrom by GPIB tool first, i can be lost any time on old unit.
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 10, 2015, 11:28:27 am
Thanks TiN, I appreciate you being so helpful by putting all your work up on the web so others can travel the path so much more easily.
It will be a few days before I get my unit, so I am reading already!
Title: Re: Repair : Old rusty HP 3458A
Post by: Monittosan on November 10, 2015, 11:36:28 am
Thanks TiN, I appreciate you being so helpful by putting all your work up on the web so others can travel the path so much more easily.
It will be a few days before I get my unit, so I am reading already!

I wish you lived in Melbourne I would of dropped it off to you :D
Title: Re: Repair : Old rusty HP 3458A
Post by: deadlylover on November 10, 2015, 12:00:07 pm
It will be a few days before I get my unit, so I am reading already!

Keysight in Australia charges around a grand for calibration, but I don't know what uncertainties they have. I *think* it was in the range of 3.6ppm or so, they use a golden 3458A in 90day cal as reference.

TRVMS in Sydney has a 10V standard (Statronics VS4 // 1.5ppm uncertainty 95%) and 10kOhm standard (good ol' ESI SR104 // 1ppm ditto) you can use for artefact calibration, was arouuuund 600 buckeroos. This doesn't include verification of all ranges and functions, it's the external cal only.

If you're a high roller, the NMI charges an arm, leg and a kidney. The base charge was 2 grand + a couple of hundred PER RANGE. This is with their JJA, it doesn't get much better than that.

But if it's just for hobbyist use, you can send me a voltage reference/resistor and I'll measure it for you on my R6581, it was calibrated at TRVMS in March, I'm good for ~7.5ppm on 10VDC and ~9ppm on 10KOhms. Probably much better than that but I won't know until the next cal.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 10, 2015, 12:03:51 pm
Taiwan is just few seas away  O0

But I actually already have some work. Not sure if I should start other thread instead, or just post in here.

Nice and crispy:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_bot.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_top.jpg)

Also blown cap:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_cap_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_cap.jpg)

What should I do with this? Plan was to use this part as donor for parts, but I think I can fix it... No custom unobtanium ASICs on it..

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/mma_sch.png)

+18V rail is likely blown, with some (many?) other parts dead on it's way. C305 sits on +18VDC too.

P.S. No, my 3458A still OK, it's another A1 DC board  ::)  :-BROKE
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 10, 2015, 12:11:59 pm
I don't know about Oz, but Agilent was selling full service contracts for the 3458A as long as it was passing calibration. I was able to get a 5 year contract on mine regardless of its age. Few companies are willing to support equipment that old. The price, IIRC, was about $180/yr. I am not sure about current pricing or restrictions.

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 10, 2015, 12:14:21 pm
Wasn't that a deal only if you pay full $2.6K cal first?
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 10, 2015, 01:41:33 pm
TRVMS in Sydney has a 10V standard (Statronics VS4 // 1.5ppm uncertainty 95%) and 10kOhm standard (good ol' ESI SR104 // 1ppm ditto)

Doesn't somebody else in Sydney have a 10kOhm 0.1ppm standard?  ;)

https://www.youtube.com/watch?v=UYGl0vebWN8&feature=youtu.be&t=2m24s (https://www.youtube.com/watch?v=UYGl0vebWN8&feature=youtu.be&t=2m24s)

Dave has yet to make a voltnut vid using this. I guess he's waiting for a JJA to arrive in the mailbag  :D
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 10, 2015, 01:49:24 pm
I went with the standard (lowest price) calibration and they were willing to offer me a 3 or 4 year contract afterwards. I had to talk with someone else within the company that would agree to the 5 year. Not sure if the folks at Loveland were aware of all the contract options.
Title: Re: Repair : Old rusty HP 3458A
Post by: deadlylover on November 10, 2015, 02:21:44 pm
I went with the standard (lowest price) calibration and they were willing to offer me a 3 or 4 year contract afterwards.

Mate do you remember off hand what the uncertainty was for your 3458A @ 10VDC at time of calibration? I have no idea if it's included in the data for the standard cal. (which is a bloody shame considering what they're charging eh?)

Doesn't somebody else in Sydney have a 10kOhm 0.1ppm standard?  ;)

That's a very nice transfer standard specced at 1ppm/yr.  ^-^

Ugh I need to get around to building a LTZ1000 based reference & ordering a bunch of resistors from Edwin, but the AUD is like monopoly money now...  :'(
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 10, 2015, 02:35:38 pm
I will have to look it up later and see if it was spec'd. It is a shame and certainly a lower cost cal can be found elsewhere. The biggest benefit to me is if it goes in for cal and it fails, the same people repair it. I haven't researched if there is an additional cost for the second calibration but I would assume there would be a partial credit on the first, and full charge on the second. That should have been something I should have asked but didn't think of at the time.
Title: Re: Repair : Old rusty HP 3458A
Post by: bingo600 on November 10, 2015, 06:36:39 pm
@TiN, MM and Dr F, I think you have a lot to answer for ! (HiHi)
I have just bought a 3458A that needs a little love (1 Fault = RAM Test Low) for a reasonable "Australian" price

Congrats & welcome to the '58 Club  :-+

/Bingo
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 10, 2015, 06:55:44 pm
Congratulations and hopefully you will have minimal issues outside of replacing the nvram.
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 10, 2015, 07:43:58 pm
Thanks, the effort that a lot of the EEVblog contributers esp TiN , by not only doing the repair and showing pictures but also documenting the job give me a bit more confidence to 'have a go ya mug' HiHi.
Title: Re: Repair : Old rusty HP 3458A
Post by: lowimpedance on November 10, 2015, 10:39:23 pm
If you're a high roller, the NMI charges an arm, leg and a kidney. The base charge was 2 grand + a couple of hundred PER RANGE. This is with their JJA, it doesn't get much better than that.
Your soul will be required too  ;)


To late to call the fire dept. then  :D
Nice and crispy:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_bot.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_top.jpg)


Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 12, 2015, 05:58:51 pm
Since somebody asked in other thread, here are few datalogs on ranges/ppm shorted input noise (using my short 4W PCB)

ACV (in SYNC mode, LFILTER ON):

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/comp_acv_sync.png)

OHMs (up to 1000 range, need rerun rest ranges). It is definately looks like out of wack..

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/comp_ohm_2w.png)

Script for ohm readings (I'll run it later again, for all ranges)
EZGPIB Script for 3458A ohms (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/HP3458A_Measure_DMM_Noise_10S.488).

Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 14, 2015, 09:47:18 am
Good idea to use DISP MSG command to output empty spaces, so you will not kill VFD too quick when running long data capture sessions. Only problem, bottom line like "SMPL", "MRNG" segments still lit. DISP OFF command disables them, but it outputs "-------" dashes on main line instead  :palm:



I'll be out of town this weekend, so meter will be left on, running this piece of code for 2 days.

Hello TiN,

It's no problem to blank the display completely including the annunciators, and without changing the firmware code.  8)  I just tested that.  :-+

Simply send "DISP OFF" plus a message text, that is a blank string inside two single quotation marks (!!), to the 3458A:  DISP OFF,'    '

Explanation - as always RTFM >:D - in the user manual, chapter 6 - Command Reference, about "DISP", and the last line of the examples contains the crucial hint, p. 171/172 of the online pdf document!

You only may have to format these quotation marks correctly in your compiler, as these also were used for text string delimiters in many programming languages.
In Pascal the text string has to be formatted as:

     cmd:= 'DISP OFF,''    ''';

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 14, 2015, 09:54:57 am
 :-+ Yea, it always helps to RTFM, sorry for dumb questions.

It's can be a very bad habit to go always most difficult way to do something simple..

I seem also to discover why my noise numbers on slow NPLCs are bad:

NPLC 50, 10VDC

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/nplc50.png)

NPLC 1000, 10VDC

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/nplc1000.png)

There are these wierd steps, with period 20 minutes. I rechecked today, everything in room except PC is turned off.
Maybe it's refrigerator? :)

Eh.
Title: Re: Repair : Old rusty HP 3458A
Post by: deadlylover on November 14, 2015, 02:11:32 pm
Thanks TiN for testing the ACV for me. ^^

I really need to set up a computer in the lab so I can start logging data, maybe I can just use the math function to get STDEV on the R6581 as an appetiser...

In regards to DISP OFF giving you dashes, could be worse;  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 15, 2015, 12:44:20 am
My new 'baby' arrived, all intact form the travels. Clean on the outside, under a ~2009 calibration seal, the inside looks like someone had smoked near it, lots of really fine black dust esp near the fan, unfortunately that is also close to the voltage reference. It had a known NVRAM failure (replacements arriving soon I hope) but also showed an ACAL AC required warning, (photo1) on first ACAL ALL , showed a new ?downslope error fault ( didn't photograph) but thought all that smoke wouldn't be good. After 2-3hours of cleaning with static protection, and re do ACAL AC it has resolved. Still need new NVRAM.

What programs do you guys use to 'talk' to your 3458, I have a Prologic GPIB-USB and Win XP PC? (PS I am not a good programmer!!!!!)
I want a good copy of the cal data before I change even the non CAL RAM.


Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 15, 2015, 01:05:26 am
Yes, dust is not uncommon. Some 3458A appear to live their lives in a dirty/dusty environment as I have seen similar crud in a few. Some of the Vishay resistors on the reference board look twisted, or it could be the angle of the photo.

I believe there were multiple scripts posted recently but I cannot remember if it was this thread or the 3245A thread.

You can download the utility from here ...  https://xdevs.com/article/hp3458a_gpib/#summary (https://xdevs.com/article/hp3458a_gpib/#summary) Scroll to the bottom of the page.

The 110 Error may indicate some or all cal data is corrupted but it couldn't hurt to back it up anyway as desoldering old NVRAM is pretty risky.
Title: Re: Repair : Old rusty HP 3458A
Post by: 3roomlab on November 15, 2015, 02:21:17 am
Taiwan is just few seas away  O0

But I actually already have some work. Not sure if I should start other thread instead, or just post in here.

Nice and crispy:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_bot_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_bot.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_top_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_top.jpg)

Also blown cap:

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_cap_1.jpg) (http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/ma1_cap.jpg)

What should I do with this? Plan was to use this part as donor for parts, but I think I can fix it... No custom unobtanium ASICs on it..

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/img/mmr/mma_sch.png)

+18V rail is likely blown, with some (many?) other parts dead on it's way. C305 sits on +18VDC too.

P.S. No, my 3458A still OK, it's another A1 DC board  ::)  :-BROKE

this board mounted vertical? it seem like the "fire" is cooking other components :( ? and alot more components barbecued
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on November 15, 2015, 07:45:25 am
My new 'baby' arrived, all intact form the travels. Clean on the outside, under a ~2009 calibration seal, the inside looks like someone had smoked near it, lots of really fine black dust esp near the fan, unfortunately that is also close to the voltage reference. It had a known NVRAM failure (replacements arriving soon I hope) but also showed an ACAL AC required warning, (photo1) on first ACAL ALL , showed a new ?downslope error fault ( didn't photograph) but thought all that smoke wouldn't be good. After 2-3hours of cleaning with static protection, and re do ACAL AC it has resolved. Still need new NVRAM.

What programs do you guys use to 'talk' to your 3458, I have a Prologic GPIB-USB and Win XP PC? (PS I am not a good programmer!!!!!)
I want a good copy of the cal data before I change even the non CAL RAM.

That fine black dust has been inside every piece of test gear I have purchased that was used in any kind of industrial environment. I don't think it has anything to do with smoking(you'd smell it if it was). The stuff is generally pretty sticky, I've had some luck removing it with a 3M static safe vacuum but in extreme cases it requires compressed air which is not ESD safe.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 15, 2015, 08:14:25 am
Quote
ew ?downslope error fault ( didn't photograph)
Auch, hope it would not haunt your unit back later.

Keep us posted! Hope your repair would be easier than mine  ^-^
Title: Re: Repair : Old rusty HP 3458A
Post by: bingo600 on November 15, 2015, 08:45:51 am
What programs do you guys use to 'talk' to your 3458, I have a Prologic GPIB-USB and Win XP PC? (PS I am not a good programmer!!!!!)
I want a good copy of the cal data before I change even the non CAL RAM.

PHK uses a prologic with pylt
https://github.com/bsdphk/pylt (https://github.com/bsdphk/pylt)

And i think that John Miles toolkit supports prologic also (Windows)
http://www.ke5fx.com/gpib/readme.htm (http://www.ke5fx.com/gpib/readme.htm)

There is a 3458.exe in there , that ought to work once you have set up the toolkit

/Bingo
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 15, 2015, 11:40:28 am
Thanks guys, my programming will have to get better. I think the KE5FX route looks the simplest (and safest) path for me. I have used other components of KE5FX's suite  before for screen print off of a Spec An. Again thanks to all esp TiN, appreciate your efforts.  :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on November 15, 2015, 07:49:53 pm
Does anybody want to follow TiN restoration?
http://www.ebay.com/itm/HP-Agilent-3458A-8-1-2-Digit-Digital-Multimeter-8-5-digit-DMM-/111824831441? (http://www.ebay.com/itm/HP-Agilent-3458A-8-1-2-Digit-Digital-Multimeter-8-5-digit-DMM-/111824831441?)

seems that reference boards, switching rods and transformer are popular components (missing or faulty)
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 15, 2015, 08:04:55 pm
I wouldn't doubt it was bought from same people. Bad transformer already adds $300+ to cost. Bad inguard supply is probably repairable.

The rest is probably faulty ...
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on November 15, 2015, 08:26:21 pm
I believe that is OldSchoolTechCorner's 3458A that he bought from the same source TiN did.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 15, 2015, 11:04:38 pm
Yep, it is. I hope we will hear about it again..
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 16, 2015, 04:30:37 am
Hmm, this project would not let me go...
I had DMM hooked to freshly modified 3245A with updated reference, monitoring 10VDC output, and reading was going down and down. In just a hour it was already 1.5 ppm's low. Ran ACAL, back to initial level, and then started drifing down again.  I suspected 3245A at first, so did next:

Connected 3245A output to K2001, using same wire as it was on 3458A.
Connected EDC MV106 10VDC to 3458A at same time.
Both meters sampled via simple LabView bodge, at NPLC10 both (NPLC100 and 200 shown same drift)

K2001 shown stable 10V output from 3245A, with noise ~1.2ppm (normal for 2001).
3458A drifted down again.

Then reversed sources (MV106 to K2001, 3245A to 3458A) , same stuff. After 5 hours it drifted down -6.5ppm's already. It's not room ambient temperature, it kept fairly constant ~27°C. I tried running colder (~22°C) and drift speed was bit faster, but value not return back when warmed up back to +27°C.

This morning switched sources back again, will see what happen when I get back home.  :-/O

There is a service note 18A (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/service/3458A-18A.pdf), describing long-term and short-term drift issue. One of parts mention A9 reference returning to "pre-aged" state if left unpowered for long time, so I hope that's the case. I have meter for a week 24/7 already, note mentions 6 weeks to return to normal condition.
Other part of note suspects drifty A3 A/D board, with only solution to replace it. Oh noes, not A3 again  :scared:

I'll hook DMM to measure actual A9 LTZ's output to see what is happening with reference voltage.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 16, 2015, 04:48:22 am
TiN,

You may need more time. Attached is a spreadsheet for two 3458A's that I monitored for almost two weeks last year. They were both turned off for months and then left on for a couple of days before I started taking readings. Day 1 is after ~48 hrs warmup.

All data was recorded in Open Office. Hopefully, there is nothing that shows any serious issues with my 3458A's  :scared:
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 16, 2015, 04:52:52 am
Can you save in Excel, plz?
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 16, 2015, 04:56:51 am
Here you go. If this doesn't work, then I have more options.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 16, 2015, 04:59:04 am
Converted to PDF for openness  :) Thanks.
I'll do monitoring during this week for CAL 72, as SN 18 tells and make same looking data.
Have bad feeling for this...  :'(
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 16, 2015, 05:02:52 am
The results include all data. I think the service note only asks for 7 days or so for the results to be valid. I didn't like my numbers so I kept on recording them.

Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 16, 2015, 05:44:28 am
TiN,
You did not mention using ACAL in between? I mean after the first ACAL after one hour, and especially, when you changed room temperature.
It is very important to run this ACAL regularly, even if ambient does not change, but it's necessary if the RT changes by 1°C only!!

If ACAL DCV always brings reading back to the initial reading, the LTZ will not be the source of this excessive drift, and AN18 would not apply!!

The other components for DCV inside the 3458A have TCs of about 1ppm/K.
The only other possible source of drift in the DCV 10 range are the amplification resistors inside the A/D ASIC, which generate the +/-12V references for the multislope conversion. As said, an ACAL DCV will always cancel also their drift, if the LTZ itself is stable.

But if you did use ACAL more often than you described, and the 3458A did not display the original value afterwards, only then the LTZ itself may drift, due to the previous 95•C oven temp, i.e. it might show  hysteresis in form of slow creeping.

Maybe, in this case only, you directly check LTZ voltage, which you should know from initial assembly.

PS: Verify, that AZERO is ON! (annunciator in display NOT lit)

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: acbern on November 16, 2015, 08:58:54 am
As Dr Frank points out, ACAL heals the usual drifts, and needs to be done frequently. More frequently than most users probably think, in my experience at least. You only find that out if you measure a source more stable than the 3458A, which may be rarely the case. So having one is nice. Other high accuracy meters which do not have a digital ACAL-like function may be inherently more stable (within certain limits). Thats probably the price you pay using a 3458A.
 
The AN 18A also describes a second cause of drift that may caue the unit to be out of spec, besides the LTZ1000, which is the hybrid used on the A/D. I have seen hybrids with the ceramic package (coincidence or not, at least reasonable due to hermeticity issues) be more stable, and the older types with the metal cover often seem to be at the edge or slighly above the SN 18A limits. Thats not too bad, actually, it only means you need to run ACAL more often (but thats good practice anyway).

Maybe what you see (likely amongs others, since 6.5ppm in 5 hours is quite a lot) is an excessive drift of that hybrid. What I would recommend is to do the SN 18A test (which takes a week, but after 2 days you can see a trend). I would recommend to read the related parameter on a daily basis, you then also see if it converges or just continues to drift away (may take you longer than 7 days to figure that out). I remember had that test done on one unit some time ago and the daily drift and the overal 7 day drift where in direct relationship (and only slightly above limit, no issue for use of the item once you know). As Keysight requires the test do be done for 7 days, they most likely assume that there are units that initially drift more and then converge, and meet spec in a 7 day window, but not after say 2 days. Doing a test once a day gives more data points with respect to this matter.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 16, 2015, 11:28:33 am
I got impression before that ACAL is targeted to cancel errors from temperature deviation. E.g. if meter was calibrated at +23C , but later ambient raised to +28C then ACAL would adjust gain and offsets to bring it back "in-cal", but now for 28C. Plus error of 40K VPG resistor tempco itself. So if temperature stays constant, ACAL should be doing almost nothing. This is also confirmed by Fluke's metrology papers I was reading before.

Also second to that, such large drift (more than 6 times of one by Keithley 2001, which have LM399), is not normal, even without any ACAL. So yes, I'll do 18A's and Ref measurement test and to see how it goes.

Main purpose of getting meter like 3458A is to measure more stable sources, either short or long-term, and watching it drift away such as this kinda defeats the purpose, as it would surpass 1year specs in just few days!

Graph data:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/test_drft.png)

Step ~8K seconds - changed EDC MV106 to 3245A outputs.
Hard to see, but just before end of graph - I did ACAL few minutes ago, and it does go back 9.99998 VDC (and already 9.999972 while I posted this).
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 16, 2015, 11:56:00 am
I got impression before that ACAL is targeted to cancel errors from temperature deviation. E.g. if meter was calibrated at +23C , but later ambient raised to +28C then ACAL would adjust gain and offsets to bring it back "in-cal", but now for 28C. Plus error of 40K VPG resistor tempco itself. So if temperature stays constant, ACAL should be doing almost nothing. This is also confirmed by Fluke's metrology papers I was reading before.

Also second to that, such large drift (more than 6 times of one by Keithley 2001, which have LM399), is not normal, even without any ACAL. So yes, I'll do 18A's and Ref measurement test and to see how it goes.

Main purpose of getting meter like 3458A is to measure more stable sources, either short or long-term, and watching it drift away such as this kinda defeats the purpose, as it would surpass 1year specs in just few days!

Hello TiN,
you are basically completely right about the function of ACAL.

For a good working instrument , as the ones of ManateeMafia, acbern, and mine, you may achieve stabilities on the 3458A on the order of ~ 0.1ppm over >24h, but without ACAL in between (!), when ambient temperature is constant. I have measured exactly that, over 35h w/o ACAL!!

Anyhow, ACAL is an important function for the 3458A, so should not be underestimated to be used regularly.

You have initially drawn the wrong conclusion from that strong drift, i.e. that the LTZ reference is not ok.
AS ACAL brings reading back to origin, your LTZ ref is definitely ok.

The other possibility , i.e. a drifty ADC ASIC (also mentioned in the AN18, which I did not remember) is the other possibility, or maybe a problem with AZERO, which you might easily check with zero input.

And you're also correct, that drift you see, is much too high to be explained by the known bugs .. so I hope you will find a "reversible" error instead.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 16, 2015, 03:56:06 pm
Time to swap ASIC's over between the 2 boards perhaps? (We didn't find out if the earlier boards ASIC is faulty after all).

This 3458A repair is a bit of a rollercoaster  :popcorn: No wonder OldSchool' got shut of his. I hope the new owner has the same tenacity as TiN  :-+ (come out, whoever you are! ;) )
Title: Re: Repair : Old rusty HP 3458A
Post by: Bill158 on November 16, 2015, 03:58:34 pm

Hello TiN,

It's no problem to blank the display completely including the annunciators, and without changing the firmware code.  8)  I just tested that.  :-+

Simply send "DISP OFF" plus a message text, that is a blank string inside two single quotation marks (!!), to the 3458A:  DISP OFF,'    '

Explanation - as always RTFM >:D - in the user manual, chapter 6 - Command Reference, about "DISP", and the last line of the examples contains the crucial hint, p. 171/172 of the online pdf document!

You only may have to format these quotation marks correctly in your compiler, as these also were used for text string delimiters in many programming languages.
In Pascal the text string has to be formatted as:

     cmd:= 'DISP OFF,''    ''';

Frank


I haven't seen this method discussed before but pardon me if it has been presented.  If the 3458A is not under GPIB control and you want to turn the display completely off.  From the front panel press "BLUE" to get to the Command menu and then scroll to the "DISP" command.  Enter ">" and then scroll to the "DISP MSG" command and then press "ENTER".   The display will be completely blanked except for the "SMPL" which blinks every time a sample is completed.  To get the display back just press "ENTER" again.  I don't know if this saves the display from aging and going dim.  I am not that familiar with VFDs.  Maybe someone with more knowledge and experience on this subject can give us some more information.
Bill
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 16, 2015, 04:21:20 pm
This 3458A repair is a bit of a rollercoaster  :popcorn: No wonder OldSchool' got shut of his. I hope the new owner has the same tenacity as TiN  :-+ (come out, whoever you are! ;) )

Agreed. I have been doing the beer and popcorn routine for the last week. Wonder why I haven't gotten my current project fixed yet?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 16, 2015, 04:28:21 pm
Bill158, your way does not remove annunciators, basically it's same as sending DISP MSG,'    '; GPIB.

There are two main reasons why our lovely VFD screens die out:
1. Segments which are being turned on for long time are loosing their active layer, causing brightness drop. Only way to help this - don't let pixels be lit for long time, if you don't need them. You could mitigate this a bit by raising driving current, but that would just speed whole dimming process even more.
2. Filament getting oxidized from constant operation, reducing overall efficiency of tube emission. This can be improved by temporary driving filament with much higher current till it red glows to burn oxides off. I covered this in detail on Keithley 2000 VFD rejuvenation task (https://xdevs.com/fix/kei2000/).

Having fun, guys? That's okay, one day truck with golden bars will crash on my street too  :box: :-DD

Attached coax cable to LTZ A9 output, hooked to K2001.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/test/test_2.png)

Guess what, it's not doing it now! Murphy gotcha. LTZ output stays within 1.8ppm window, likely much much less, K2001 just have more noise (I have LED lights around on, soldering iron on, Tek LA on, far from quiet setup now). 3458A and 2002 connected via same cable to EDC MV106 10V, both NPLC 50, both MATH nulled at beginning of measurements.

3458A shows 7.5uV (0.75ppm), 2002 shows 12.3uV (1.23ppm).

 :palm:
Title: Re: Repair : Old rusty HP 3458A
Post by: Bill158 on November 16, 2015, 08:34:18 pm
Bill158, your way does not remove annunciators, basically it's same as sending DISP MSG,'    '; GPIB.

There are two main reasons why our lovely VFD screens die out:
1. Segments which are being turned on for long time are loosing their active layer, causing brightness drop. Only way to help this - don't let pixels be lit for long time, if you don't need them. You could mitigate this a bit by raising driving current, but that would just speed whole dimming process even more.
2. Filament getting oxidized from constant operation, reducing overall efficiency of tube emission. This can be improved by temporary driving filament with much higher current till it red glows to burn oxides off. I covered this in detail on Keithley 2000 VFD rejuvenation task (https://xdevs.com/fix/kei2000/).


All I was trying to do was turn off the pixels so that #1 wouldn't be happening as fast as leaving them on.  The fact that the "SMPL" flashes once in a while isn't going to cause much degradation if any.  I figured that these VFDs would be very much like a CRT in an oscilloscope.  Even if you turn the intensity all the way down you are still causing oxidation of the cathode.  Look at many 576/577 curve tracers where the intensity was left up but just a dot at the lower left corner of the CRT.  Burned a hole in the phosphor so that it is dim right at that spot.  But at least you are not losing the active layer on the pixels if you don't have the display showing anything.
Thanks for the answer on VFDs.
Bill
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 16, 2015, 11:02:50 pm
Just got off the phone from Keysight Australia, 
Standard Calibration (including altering cal ram if needed)  $1331 (plus gst)  7-10 working days,
NATA calibration (includes error bars)  AUD $1730(plus gst)
One time repair (if not grossly damaged) AUD$3343 (plus gst).
Ooooh ooooh!
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 17, 2015, 12:26:54 am
I don't understand why hobbyists are really arsed about NIST traceable calibration, etc. Even with it the instrument could pass and be grossly out of what we really want (which is perfection!). The manufacturers stated cal figures are the extreme ends of the bell curve. Yes, as engineers we have to treat all devices as if they are at that extreme. But just not MY device, mmmkay!   >:D

Now I guess the cal lab will simply pass anything even at the ends of the curve rather than bother with actually adjusting the device to meet spec. When you pay extra so they do adjust they don't bother perfectly zeroing the adjustment, just make sure it is within the min-max deviation.

All of this is great for traceable calibration performed by and for grunts who act like trained monkeys. It allows a way of tracing legal blame for when a space shuttle explodes, a drone misses target, or a nuclear power plant goes spreading it's radioactive goodness around the planet...

I just want all my instruments to agree with each other. The "Macbeth volt" and the "Macbeth second" are more important to me. Of course I want them to be exactly 1V and 1Hz in the rest of the natural universe as well as just in my lab, but I'm not so disappointed if my 1V is 10ppm out... ok maybe I am, 1ppm isn't so bad...

If we can get the "EEVBlog volt" which is basically all the voltnuts accuracy averaged then I reckon it will be a better standard than NIST anyway :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 17, 2015, 01:01:32 am
VK5RC

If you asking HPAK to repair your 3458A, you doing it wrong  :-DD.
Welcome to high-end gear. It's "normal" out there.

Macbeth
Yes, but no. We want perfect, right? How much perfect is only matter of disposable funds available...

Drift ain't there now  :rant: overnight span ~2.4ppm (temp change 26.1C to 30.3C), so that's OK.
I have wild theory now why it's not drifting now. No, A3 not changed, I did not even unscrew bottom cover yesterday. You guess? :D
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 17, 2015, 01:10:16 am
Air filter?
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 17, 2015, 02:12:07 am
I know, I know!!! That bloody cat is opening doors and letting the drafts in!  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 17, 2015, 04:08:02 am
No, not so obvious as air filter.
And no pets allowed in volt-nut house  :-DD.

Hint - it's not temperature or voltage related.  ;)

Title: Re: Repair : Old rusty HP 3458A
Post by: Vgkid on November 17, 2015, 04:34:49 am
Bad power connection/cable.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 17, 2015, 04:40:37 am
Nop. Nothing obvious, this one is tricky.
Title: Re: Repair : Old rusty HP 3458A
Post by: crispy_tofu on November 17, 2015, 06:11:55 am
I was thinking something along the lines of a wobbly connection in the banana inputs, but it's not obvious...
Dodgy software?  :-//
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 17, 2015, 07:32:00 am
?Dissimilar metals of connection cable/connectors??

RE HP-A-KS just thought I would phone them to see how much in AUS, it is part of my tendency to "nuttery" voltage or time!!!! :scared:

Reminds me of the joke "a man with one clock knows the time, a man with two is not so sure" perhaps "a man with one DMM knows the voltage……. etc"

I have a slightly bulgy main 15000uF in the main PSU, a replacement is coming soon.
Title: Re: Repair : Old rusty HP 3458A
Post by: deadlylover on November 17, 2015, 07:55:19 am
I have a slightly bulgy main 15000uF in the main PSU, a replacement is coming soon.

Hmm I might replace all electrolytics, because once you get it calibrated you don't want to ever open the thing up again until it requires repair.

Nop. Nothing obvious, this one is tricky.

Humidity/moisture in parts being released after a long cycle?  ^-^
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on November 17, 2015, 08:49:54 am
My guess - thermal EMF
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 17, 2015, 10:05:06 am
plesa is close, but no, not EMF :) Not related to thermals.  >:D
Title: Re: Repair : Old rusty HP 3458A
Post by: Monittosan on November 17, 2015, 10:13:22 am
?Dissimilar metals of connection cable/connectors??

RE HP-A-KS just thought I would phone them to see how much in AUS, it is part of my tendency to "nuttery" voltage or time!!!! :scared:

Reminds me of the joke "a man with one clock knows the time, a man with two is not so sure" perhaps "a man with one DMM knows the voltage……. etc"

I have a slightly bulgy main 15000uF in the main PSU, a replacement is coming soon.

If its ok by TiN pics pics pics! I had to stop my self from opening your 3458A soooo many times just to keep the cal seal intact and let the next owner have the satisfaction of cracking it open  ;D
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 17, 2015, 10:53:30 am
plesa is close, but no, not EMF :) Not related to thermals.  >:D

Maybe, for this missing shorting jumper on jack P100, you used a TiNned one, instead of gold plated?
Oxydation might create unwanted chemical galvanic element in the signal path.

You know, P100 near the A9 PCB, which selects GND, +7V, or Normal, and which you might have used (and touched) for measuring A9 output.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 17, 2015, 01:36:26 pm
Dr Frank,
 That would be a good catch even if it wasn't the main problem. At least TiN has a donor board to get a jumper.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 17, 2015, 02:13:04 pm
Dr Frank,
 That would be a good catch even if it wasn't the main problem. At least TiN has a donor board to get a jumper.

That jumper already made me nervous when I have seen it for the first time.

On 2nd thought, it may be inside the AZERO circuit, and so any parasitic voltage would be eliminated.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on November 17, 2015, 03:00:20 pm
plesa is close, but no, not EMF :) Not related to thermals.  >:D

I must give up :-//
Title: Re: Repair : Old rusty HP 3458A
Post by: WN1X on November 17, 2015, 03:31:40 pm
No, not so obvious as air filter.
And no pets allowed in volt-nut house  :-DD.

Hint - it's not temperature or voltage related.  ;)

I am going to guess it is light leakage affecting some of the IC's.
Title: Re: Repair : Old rusty HP 3458A
Post by: nfmax on November 17, 2015, 03:37:13 pm
If all else fails, blame the software ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 17, 2015, 03:46:22 pm
Test gear or other device with fan blowing warm air into rear of meter.
Title: Re: Repair : Old rusty HP 3458A
Post by: Zucca on November 17, 2015, 03:52:52 pm
I must give up :-//

You are not alone, my head is still smoking and nothing is coming out.

PS: I imagine TiN with a cold beer smiling on us  ;)
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 17, 2015, 04:02:51 pm
I would be smiling too if I knew that A3 board was working!  :phew:
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 17, 2015, 04:46:59 pm
You are not alone, my head is still smoking and nothing is coming out.

PS: I imagine TiN with a cold beer smiling on us  ;)

That's it! It's the bloody compressor cycling on his beer cooler! Should have got a peltier cooler instead.
Title: Re: Repair : Old rusty HP 3458A
Post by: teksturi on November 17, 2015, 04:48:45 pm
Power line frequency is not correct or stable or something similar.
Title: Re: Repair : Old rusty HP 3458A
Post by: WN1X on November 17, 2015, 07:08:23 pm
That's it! It's the bloody compressor cycling on his beer cooler! Should have got a peltier cooler instead.

The compressor is cycling too much because there is no thermal load for it after TiN drank all of the beer  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 17, 2015, 07:41:33 pm
The compressor is cycling too much because there is no thermal load for it after TiN drank all of the beer  :-DD
I noticed a few bottles of India Pale Ale during his clean up operation. That Taiwanese IPA is nothing like the stuff over here, I mean 5-6% abv is normal, but 99%?  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 19, 2015, 01:44:28 am
The only thing I can see that is remotely questionable is the missing screw on the A9 reference board based on the photos from xDevs. Air drafts around the LTZ1000?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 19, 2015, 07:34:26 pm
It did not go away...And likely a very bad idea here... I wish to come back to simple and easy Keithley's now!

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/adc_asic_1.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 19, 2015, 11:45:32 pm
I knew it! Take out the ASIC's and swap them - but make sure to soak them in the tears of gypsies first! :-DD

ETA: That's not some lifted pads on some of those pins I hope?  :-BROKE
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 20, 2015, 02:13:50 am
All right. I did find one more item......

Your initial pics showed the blue wire connected to the internal frame and the gray to the outer. Your final pics show them swapped around.

https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/top_open.jpg (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/top_open.jpg)

https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_top.jpg (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/final_top.jpg)


The silkscreen on the A1 even tells you how to hook them up.   ;D

Yes, it appears you have it connected properly.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 20, 2015, 04:14:11 pm
(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic3.jpg)

Decisions, decisions.... :-//
Title: Re: Repair : Old rusty HP 3458A
Post by: Jwalling on November 20, 2015, 04:18:08 pm

Decisions, decisions.... :-//

Hi Tin,

Do you have a picture of the top of the chip?
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 20, 2015, 04:31:51 pm
Put the one suspected of throwing the error in the other board first. In case the err 1 was related to some other component that wasn't changed. Plus, the other board should have all HP screened parts.

Do both boards have the same cpu markings? I don't know how many versions of the inguard fw have been released.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 20, 2015, 04:49:28 pm
If swapping them around only causes the same faults to follow them, then maybe another answer is RAVERS - Redundant Array of Very Expensive Rare Silicon.

Determine the areas of which ASIC work/not and create a riser board with both chips routing the good pins of either chip to the socket. Hell, maybe some pins other than power and grounds can be paralleled to provide further redundancy!  :-DD

Of course if swapping them and the faults stay with the original boards then the chips must be good and its a board fault.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 20, 2015, 05:14:07 pm
No, it's this bastard. Installed "ERR" chip into drify A3 PCB, did not change anything else , and yah, instant ERROR 114 - multislope or balanced rundown convergence.
So this dreaded error comes from U180, that's clear now.
I did measure resistors accessible from pins, they all were okay (will post more detail later on both chips).

Now time for opposite swap, install drify ASIC into my old A3. If it will work , than drift came from other part on A3. But I doubt that, and there is a reason why.
I took very good look on drifty ASIC , and it seems it had pencil handwriting "Drift -1.09".  :-\
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 20, 2015, 05:23:46 pm
Here's top of chip. It's barely visible, but you can help with imagination..

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/asic_drifty_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/asic_drifty.jpg)

 :-BROKE

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 20, 2015, 05:40:06 pm
Soldered Mr.Drifter into my old original  bodged up A3. NPLC 100, no errors, all working.
Let's have my little python snake run some GPIB commands and see how it's behaving. Last hope that drift was caused by something else on A3...

Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 20, 2015, 05:41:55 pm
Good luck! Just because they wrote drift 1.09 on the chip doesn't mean it is the chip at fault, just the most suspect.

ETA: Actually looks like Drift=I.09 to me, so = current * .09?
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on November 20, 2015, 05:42:03 pm
Fingers crossed for you!
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 20, 2015, 05:48:17 pm
Chip was soldered before, so it's pretty high chance it is the cause...
Anyhow, we will know tomorrow morning for sure.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/rcstr.jpg)

Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 20, 2015, 06:04:04 pm
This will be an opportunity to create some burn in procedures for those of us that will potentially buy 3458A parts or whole meters.
Title: Re: Repair : Old rusty HP 3458A
Post by: chinapp on November 20, 2015, 08:03:41 pm
attach is the  pic of the teardown of the ASIC 1NC1-0017,some people in China had  researched much on this ,the conclusion is that the most suspect is this BIG IC,the precise resistor in this IC become unstable or drift

,and the bad thing  is there is no spare for this

 :palm:
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 20, 2015, 08:12:13 pm
Interesting, do you have a link to thread?

I don't think it's precision resistor are issue in this chip. I had measure them (at least ones which connected to pins) and they read OK values. I also heated up chip by touching it with soldering iron to see if it stable with temperature, and got just a little change, so I assumed temperature stability was OK too.

I'd suspect those current balancing die instead.
Title: Re: Repair : Old rusty HP 3458A
Post by: chinapp on November 20, 2015, 09:05:26 pm
http://bbs.38hot.net/forum.php?mod=viewthread&tid=101360&highlight=%B4%F3%D0%BE%C6%AC (http://bbs.38hot.net/forum.php?mod=viewthread&tid=101360&highlight=%B4%F3%D0%BE%C6%AC)

a China bbs, 38hot,in Chinese character

 the thread is also discuss on how to repair this IC, the black zone is the precise resistor
Title: Re: Repair : Old rusty HP 3458A
Post by: chinapp on November 20, 2015, 09:09:48 pm
Interesting, do you have a link to thread?

I don't think it's precision resistor are issue in this chip. I had measure them (at least ones which connected to pins) and they read OK values. I also heated up chip by touching it with soldering iron to see if it stable with temperature, and got just a little change, so I assumed temperature stability was OK too.

I'd suspect those current balancing die instead.

there are several resistors inside that need match in good value, do you use a precise multimeter to check all the resistors ? especially the run down and run up resistor
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on November 21, 2015, 12:25:10 am
Ok I understand We can use the "active" parts of the "Hybrid IC" and arrange the resistor array outside but I do not understand how to find a suitable resistor value ?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 21, 2015, 04:29:04 am
Hmm...

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/test_oldu180.png)

I'll cleanup A3 board a bit, remove sticking out extra caps from it, assemble box and we let it sample for a day or two..
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 21, 2015, 06:22:00 am
Self-test failed, Failure 209, Timeout read A/D : 197 (flatness DAC 1V)...

Trying to get make my old A3 board functional..
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 21, 2015, 06:54:40 am
Oh no. Is this possibly related to more Elantec failures or just issues with U180?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 21, 2015, 07:34:17 am
Perhaps something else on board. I had lot of chips on it changed before.
U180 was ok on another A3 PCB, and this error is on ACV path.
Replaced U112 (I had replaced 848 to AD829 on old board, as did not have 848), Q403, R186 , CR120 from replacement A3, now testing if it will drift on DCV, to clear this parts.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 21, 2015, 10:15:49 am
Meh, I give up for now.
Tried U181, checked R181 (resistor which connects AC_AD to U180 ASIC), cleaned both A2 and A3 boards again, nada.
Had cold showers few time, when it started pop few Error 114's multislope rundown convergence errors.

Put all covers back in, will test DCV next week to see how it works. I don't need ACV now. Self-test fails same points, right in the end, where it shows TEST ACDCV 10mV and TEST ACDCV 100mV (sometimes 10mV pass) with same error FAILURE 209 : TIMEOUT READ A/D : Value 195 or Value 196.

CAL DCV, ACAL DCV,OHMs is fine. Tried swapping CAL NVRAMs too (was thinking if constants got corrupt), no change..
Hope one day another A3 pop up on ebay, so I can get back to it.
Title: Re: Repair : Old rusty HP 3458A
Post by: KJDS on November 21, 2015, 11:05:44 am
I nearly bought a 3458A in an unknown state earlier in the week.

I'm now glad I stopped bidding when I did and left it to someone else.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 21, 2015, 06:51:30 pm
These instruments are not for weak-hearted people, I can tell you that..

Here's python I'm running now, which samples DCV, calculates ppm deviation from hardcoded value [n]level[/b] and prints it on meter's display.
It also creates three CSV files (one with measured voltage, another one with temperature logs, third with ppm deviation calculations).
Don't ask why not single file with three values together :).

Temperature is read on every 25th sample (as it clicks relay to take TEMP reading, I don't want kill relays too quick).

Code: [Select]
# xDevs.com Python test GPIB DeviationPPM app
# http://xdevs.com/fix/hp3458a/
import sys
import Gpib
import time

with open('10v_oldadc_d5_nplc200.csv', 'a') as o:
    with open('10v_oldadc_d5_nplc200_temp.csv', 'a') as t:
        with open('10v_oldadc_d5_nplc200_ppm.csv', 'a') as d:
        inst = Gpib.Gpib(0,3) # Instrument GPIB Address = 17
        inst.clear()
        inst.write("PRESET NORM")
    inst.write("OFORMAT ASCII")
    inst.write("DCV 10")
        inst.write("TARM HOLD")
    inst.write("TRIG AUTO")
        inst.write("NPLC 100")
    inst.write("AZERO ON")
        inst.write("LFILTER ON")
    inst.write("NRDGS 1,AUTO")
        inst.write("MEM OFF")
        inst.write("END ALWAYS")
    inst.write("NDIG 9")

    min = 0
    tread = 100
    temp = 0.0
    level = 10.0000340
    ppm = 0
            while min <= 10000000:
min+=1
tread = tread - 1
if (tread == 0):
    tread = 25
    inst.write("TARM SGL,1")
    inst.write("TEMP?")
    temp = inst.read()
    print(time.strftime("%d/%m/%Y-%H:%M:%S; < TEMP") + ("%d;%4.1f;\r\n" % (min, float(temp) ) ))
    t.write(time.strftime("%d/%m/%Y-%H:%M:%S;") + ("%d;%4.1f;\r\n" % (min, float(temp) ) ))
inst.write("TARM SGL,1")
data = inst.read()
ppm = ((level / float(data))-1)*1E6
d.write (time.strftime("%d/%m/%Y-%H:%M:%S;") + ("%d;%16.16f;\r\n" % (min, float(ppm) ) ))
inst.write("DISP MSG,\"%12.4f ppm\"" % float(ppm))
time.sleep(1)
print time.strftime("%d/%m/%Y-%H:%M:%S;") + ("[%8d]: %16.16f , dev %12.4f ppm" % (min, float(data),float(ppm) ) )
o.write (time.strftime("%d/%m/%Y-%H:%M:%S;") + ("%d;%16.16f;\r\n" % (min, float(data) ) ))
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 23, 2015, 11:44:25 am
(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/test/drifting.png)

Same stuff, ran away 16ppm in just about 16.73 hours. +0.96ppm/hour  :-//
I added temp readings too, just to be sure. It's very well unrelated...
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 23, 2015, 12:00:19 pm
Hi TiN,

did you also monitor the + / - 12V reference voltages directly at the A/D hybrid, if these run away?

Frank

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 23, 2015, 01:36:22 pm
Not yet. I moved 3245 (10V source), 3458 (sick bastard), K2001 (control meter) into other room, connected only to Raspberry Pi running simple Python app (https://xdevs.com/article/hp3458a_gpib/) , to capture data and send to FTP in realtime, to test this over this week.
Then will be testing one part at a time. Good idea about references.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/test_jig.jpg) (https://xdevs.com/datalog_cal/)

Here's new test rig.

EDIT: On photo click - realtime datalog chart , updated every 7 seconds.

EDIT2: So far same -0.98ppm/hour. K2001 stays within 1ppm about 10.0000125 VDC, just to make sure that 10V 3245A source is stable (it was measured with K2002 before as well). I have wild idea to freeze bad ASIC on second A3 board with -196°C to cycle it few times. Maybe it will help? :D
Lol, this is most popular thread in repair section here by big margin. Would never know fixing dead 9K$ DMM would be so popular?
Title: Re: Repair : Old rusty HP 3458A
Post by: BFX on November 23, 2015, 07:28:42 pm
TiN you are crazy  8)   :-+
Good Job
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 24, 2015, 10:07:18 am
TiN=ABSOLUTELY crazy. Still waiting for my DS1220, otherwise my little baby (3458) is up and running, getting a Rasp Pi, and learning a bit more code (Arrrrrgggh)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 24, 2015, 10:31:06 am
What is crazy? I don't even know Python,  :P.
Obviously there is issue, as it script hangs sometimes. I suspect frequent FTP-connections cause of it.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 24, 2015, 11:14:55 am


 I have wild idea to freeze bad ASIC on second A3 board with -196°C to cycle it few times. Maybe it will help? :D

That's really crazy. What positive effect should that have??

If you want to destroy the resistor array inside completely by thermal shock of liq-N2, causing cracks in the resistor film and its top layer protection, just go ahead.
Maybe the outer case will also crack.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 24, 2015, 11:21:07 am
That ASIC not working properly anyway. And ceramics usually not so bad with slow temperature gradient.

Anyway, lets read reference voltages on Mr.Drifty. its -26ppm now, just from sitting on , not even sampling half a day.

K2001 is only 1ppm up. Take that, 3458A :D
Title: Re: Repair : Old rusty HP 3458A
Post by: nfmax on November 24, 2015, 12:36:09 pm
This is a crazy way to learn Python!
Title: Re: Repair : Old rusty HP 3458A
Post by: HighVoltage on November 24, 2015, 12:59:05 pm
TiN,
It is amazing how much work you have put in to this broken 3458A and we all have learned so much from you.

There have been several 3458A been sold on ebay France in the last few weeks for very low prices and some of them in good working condition:
http://www.ebay.fr/sch/i.html?_odkw=3458A&LH_Complete=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XAgilent+3458A.TRS0&_nkw=Agilent+3458A&_sacat=0 (http://www.ebay.fr/sch/i.html?_odkw=3458A&LH_Complete=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XAgilent+3458A.TRS0&_nkw=Agilent+3458A&_sacat=0)

I think I will wait for another one of these to come along, since I don't think I would have the patience to repair one like you did.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 24, 2015, 01:07:02 pm
Well, I did not discover much new, just wish I could get working instrument though. It's a time black hole..
I guess law of balance is in works, due to 3245A which was "repaired" in one minute  :D
Title: Re: Repair : Old rusty HP 3458A
Post by: Zucca on November 24, 2015, 03:22:36 pm
...was "repaired" in one minute  :D

and "improved" with a killing LTZ1000ACH in 10 minutes... :D. A master piece.
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on November 24, 2015, 08:15:07 pm
Lol, this is most popular thread in repair section here by big margin. Would never know fixing dead 9K$ DMM would be so popular?

Even if most of us never own a 3458A I think we all respect it and desperately want you to be successful, so of course we're following your efforts closely!
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on November 25, 2015, 05:17:48 am
Are this ASIC not available from agilent ?
Sorry my experience with agilent so far are replace 20pcs tantalum cap from my 8590L and replace fuse from my 34401A :palm:
Title: Re: Repair : Old rusty HP 3458A
Post by: Monittosan on November 25, 2015, 10:44:46 am
TiN,
It is amazing how much work you have put in to this broken 3458A and we all have learned so much from you.

There have been several 3458A been sold on ebay France in the last few weeks for very low prices and some of them in good working condition:
http://www.ebay.fr/sch/i.html?_odkw=3458A&LH_Complete=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XAgilent+3458A.TRS0&_nkw=Agilent+3458A&_sacat=0 (http://www.ebay.fr/sch/i.html?_odkw=3458A&LH_Complete=1&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.H0.XAgilent+3458A.TRS0&_nkw=Agilent+3458A&_sacat=0)


I think I will wait for another one of these to come along, since I don't think I would have the patience to repair one like you did.

My old meters in that link  :D

Tin I think there are a lot of people out there that just love the idea that ultra high end equipment is repairable. Give hope to owing equipment you otherwise would not be able to justify.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on November 25, 2015, 11:13:26 am
Are this ASIC not available from agilent ?
Sorry my experience with agilent so far are replace 20pcs tantalum cap from my 8590L and replace fuse from my 34401A :palm:

Nope - http://www.keysight.com/my/faces/partDetail.jspx?partNumber=1NC1-0017 (http://www.keysight.com/my/faces/partDetail.jspx?partNumber=1NC1-0017)

However the complete A/D board appears to be available for GBP 898 with the old board traded in.

http://www.keysight.com/my/faces/partDetail.jspx?partNumber=03458-66513 (http://www.keysight.com/my/faces/partDetail.jspx?partNumber=03458-66513)
Title: Re: Repair : Old rusty HP 3458A
Post by: crispy_tofu on November 26, 2015, 02:23:44 am
here is another 8.5 digit for the "picking" :P
http://www.ebay.com/itm/Solartron-Schlumberger-7081-Precision-Voltmeter-/121661653123?hash=item1c53998083:g:NuAAAOSwstxVZIEd (http://www.ebay.com/itm/Solartron-Schlumberger-7081-Precision-Voltmeter-/121661653123?hash=item1c53998083:g:NuAAAOSwstxVZIEd)

Stop tempting him!  >:D >:D >:D
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 26, 2015, 06:15:38 pm
You guys can have it, I'm done with dead stuff for now  :P.

Hooked up 2002 to scan those A3 voltages. Here's first hour result:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/adcdr1_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/adcdr1.png)

Legend is on graph. All plots are normalized to 2ppm scale.

Setup itself:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_scan_setup_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_scan_setup.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_scan1_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_scan1.jpg)

All signals wired to 2001-TCSCAN inside 2002. All shields and covers are installed in place, to keep same thermals.  :-DMM
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 26, 2015, 06:19:32 pm
Also poked around with thermacam.

That buffer on A2 AC board is cooking... It was like that even before though, it does not affect DC path, meter working even if I remove it (chip is in the collet socket)...

Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on November 26, 2015, 07:08:01 pm
Sadness - time for a new ASIC.
Title: Re: Repair : Old rusty HP 3458A
Post by: lukier on November 26, 2015, 08:26:18 pm
Sadness - time for a new ASIC.

Probably  :(

What about other possible suspects? Integrator capacitors, opamps and comparator? Crystal oscillator (stability) that is used to clock multi-slope ASIC?

If this is the ASIC then maybe desolder it and measure slope resistors with 2001+scanner for a day or two.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 27, 2015, 01:53:41 am
OK, run overnight results:

+10Vin -14ppm
+12VREF +/-0.6ppm  :-+
-12VREF -5ppm  :-//
+5VREF -4.2ppm  :-//
LTZ ZR +/-0.5ppm  :-+

CSV-source file (http://xdevs.com/static/data/10v_keihp_nplc10.csv) for you, data-nuts.

Next step - isolate ASIC resistors for -12VREF and +5VREF opamps and hook opamps to error114 ASIC resistors instead.

EDIT:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/asic_bodge_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/asic_bodge.png)

Here's spicy stuff. I'll isolate pins 2,3,64,9,15,16 and try to use resistors from another ASIC to see if can change anything on -12 and +5 refs.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 27, 2015, 07:39:39 am
TiN,


What's strange is the continuous negative drift.
If the resistors R4, R5 (10k) inside ASIC are not correctly matched (any more), I'd expect the +12V reference and 10V reading going up and down with temperature.
It may also be possible, that U165 is damaged, like excessive input bias, or so.

But I lost overview, which ASIC is now on which PCB..so if this failure went with the ASIC, it's not so probable.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 27, 2015, 10:32:57 am
Looks like a Problem with R4 / R5 or possibbly extensive bias if U165.
The 10 V measured will be compared to a combination of the +12 V and the -12 V. So it's no so supprising that the meter reading is drifting more than the -12 V reference.

The good thing is, that it might be possibly to use external stable resistors instead of R4/R5.

Are there decouping caps direktly at the OPs ? Looks strange with resistors at the power inputs, but no caps.
 Is it possible that there is some oscillaton or excessive ringing ? This could also cause some aperent drift.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 27, 2015, 10:33:39 am
Dr.Frank
I have two A3 PCBs, original (let's call it OLD) one which came with meter, with U180 ceramic current steering ASIC throwing ERROR 114 : rundown convergence.
And second A3 PCB (let's call it NEW, while it's not technically new) which I got later, with U180 ceramic ASIC with this drift issue.

Now what I did - swapped U180 ASICs between boards. That's how I confirmed that U180 is cause of drift, not external components. Data and graphs are from old A3 PCB with "new" U180 ASIC. Now, there is a little chance that both boards have faulty parts which cause same drift, but that would be a long stretch assumption. If that would be U165, then it should have at least different speed of drift between two boards, but no, it's exactly same, about 1ppm per hour.

Yes, there is a chance that those internal resistors get damaged/mismatched. That is why I want to hook resistors from "bad OLD" ASIC to see if issue change. I plan to glue old ASIC in deadbug style right on top of ASIC in the board, so thermally everything will be same.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 27, 2015, 10:39:14 am
Yes, there are caps in close proximity, I just omit them on LTSpice sim for clarity.

Here's actual schematics from CLIP:

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_refsch_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_refsch.jpg)

I measured pin 2 on each opamp too, in case that can help? I can add plots too.
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 27, 2015, 10:56:49 am
I don't see a big advantage of using the old Chip just for the resistors. I think 2 identical resistors (or mayby later a dual resistor module (maybe LTC5400)) should be just as good. These two resistors only need to match each other.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 27, 2015, 11:25:57 am
Dr.Frank


Yes, there is a chance that those internal resistors get damaged/mismatched. That is why I want to hook resistors from "bad OLD" ASIC to see if issue change. I plan to glue old ASIC in deadbug style right on top of ASIC in the board, so thermally everything will be same.

If you read the hp journal, about the A/D network , the resistors have to be matched for equal T.C. to guarantee short term stability, between ACALs.

If your +12V reference runs monotonically in one direction, obviously independent from temperature changes, then this is probably a constantly running degradation process of one of the two 10k resistors.
Something like constant corrosion, if for example the protection film on top has pinholes.

That's really strange.

I also do not know anything about the resistor technology, HP had used.
They have also their FineLine arrays, since the early 80ties, also unknown to me, what they use.

I assume, that could be something like TaN technology, as it has to be superior over Thin Film technology ( Ni/Si/Cr system).

Anyhow, maybe you can identify the root cause by bodging 2 external  ~10k Vishay resistors.

Frank

PS: Another idea: if you can really exclude the external components, then you may observe this continuous drift directly by measuring R4 or R5. Hopefully, the about 1.0 test voltage from the DMM used is enough to initiate possible diffusion processes, otherwise  1mA constant current and voltage measurement by DMM is preferred.

Such corrosion processes will always increase the resistance.

As -12V is increasing by absolute value, R5 would be most suspect.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 27, 2015, 11:54:03 am
Yes, I remember HPJ. Let's see If behaviour changes, I'll look into proper resistors and networks for more permanent solution.
Thanks for suggestions, appreciate.

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 27, 2015, 02:05:08 pm
Bodged up with copper wires...

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic_bodge_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic_bodge.jpg)

Forgive the crude worker  :-/O

Changes in these REF voltages indeed impact readings. I just move cable to scan card a little, and readings change 8ppm instantly.
Set 2002 to read only -12VREF, fixed scan card at one relay only to reduce interference. Will leave it sampling log over weekend, will see. Last 40 samples reading is ~0.264ppm so far, -12VREF stays ~0.302ppm.
Title: Re: Repair : Old rusty HP 3458A
Post by: Jwalling on November 27, 2015, 02:17:14 pm
Bodged up with copper wires...

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic_bodge_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_asic_bodge.jpg)

Forgive the crude worker  :-/O

You, sir, are NUTS! :scared:
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 27, 2015, 02:37:26 pm
Dead bug style to it's best.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 27, 2015, 03:52:05 pm
I sense more pcb daughter boards for the 3458A. I hope this can prove there is a solution for your particular issue. Of course, there is plan C....
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 27, 2015, 04:00:38 pm
Well, initial results does not look good (https://xdevs.com/datalog_cal/).

There is plan D too, ditch ratiometric references, and just put three LTZs in there to make +12V, -12V and +5V references  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on November 27, 2015, 04:15:31 pm
Yes. If you need encouragement, I don't think there will be a shortage of people to give the thumbs up.

I agree that the Keithley models are much easier to service.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 27, 2015, 04:18:57 pm
Quote
I agree that the Keithley models are much easier to service.

I was sure about opposite just 2 month ago!  :-DD But yea, with Keithley's my experience was "it either works normally, or does not work at all".  :blah:

Issue with independent references is, that when any of them drift differently to others - it will magnify error.
I'll try with another opamps and without scancard wires tomorrow. Maybe my go-to LTC2057's instead of LT1001's?
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on November 27, 2015, 07:45:53 pm
You are defining  term Volt-Nut :)
I'm glad that Keithley used the of the shelf parts instead of custom made unobtanium ASICs.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 28, 2015, 05:48:36 am
It shoot thru the floor overnight.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/test/2asics.png)

-77ppm, record! Decay seem to speed up >:(
Could be resistors bad in old ASIC too?

EDIT: Bodged up LT5400A-3 instead of -12sum 10K resistors, replaced U165,U151 with LTC2057 choppers.
Let's see...
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 28, 2015, 09:11:50 am
LT1001 have offset current 0.4nA typ, 3.8nA max (+25°C) with input bias current +/-0.7nA typ, +/-4nA max (+25°C). En is about 11-18nV/SQRT, specced 300nVpkpk, GBW 0.8MHz.
LTC2057 have offset current 0.06nA typ (+25C), 0.46nA max (-40 to +85°C) with input bias current +/-0.3nA max (+25C), +/-3.5nA max (-40 to +85°C). En is about 11nV/SQRT, no 1/f noise, specced 200nVpkpk, GBW 1.5MHz

Also 2057 have total supply voltage at 36V, which means those resistors at opamp power supply pins can be removed. I left them in place for now (not sure if ASIC current balance circuit would like higher amplitude, but likely be allright, as it's charge balance ADC topology, not voltage.), but even then voltage at opamp pins is higher now, about -16.5 and +17.3VDC, due lower opamp supply current.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/ltc_a3.png)

Voltage is creeping up, likely due to heat (blue line on graph, TEMP? data). You can see control meter - K2001 - also went up about 1ppm due warmer temp (3458A sits on top of k2001).
PPM scale for 3458A reading (red line) is green scale, went up 0.6ppm from power on state , sorry for misleading coloring
Purple line is +5VREF (wire from -12VREF came out, did not bother to reassemble everything again).

As a side note, I'm impressed with 3245A+LTZ performance so far, seem to be really stable thing, likely beyond my current measuring capabilities.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 28, 2015, 06:48:30 pm
Drifted up 7ppm today, 5V reference went a deep dive (hundreds of ppms).

Now replaced 24K+10K from ASIC with external resistors (10k fluke wire wound 3ppm/K + R2R 25.5K&2*226K 25ppm/K (don't have any shmick 24K resistors here))

Will it help? Only way to find out is to let it warmup for another six hours....

What puzzles me  - if it's something caused resistors go bad in ASIC, why resistors used in +12VREF are okay and that reference is stable on both ASICs?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 29, 2015, 06:21:32 am
+16ppm overnight. But now we talking some business.

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/asic_ptf_1.png) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/asic_ptf.png)

Recap for configuration:

+12VREF - resistors from old bad error 114 ASIC
-12VREF - pair of resistors from LT5400A-3 network
+5VREF - Fluke 10K 3ppm/K resistor + RNC50J2552BS 25.5K 25ppm/K with two RNC50J2263BS 226K 25ppm/K in series to get 24.1K

Now, what you see, and why it is good?
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 29, 2015, 10:37:19 am
The 5 V are still not very good - but this was expected and does not reay matter. There seems to be no influence of that.
So maybe this is already good enough.

The +12 V and DMM reading show quite exactly a oposite trend. The -12 V very much paralles the ADC reading. So the ADC itself, comparing the 12 V to the input seem to work very good.

So the only part still not working good is the 7 V to 12 V step - but this does not need to be done in the ASIC. Due to the ACAL function of the DMM this does not even have to be long term stable - so just to resistors with well matched TC will do the job.

There a a few strange steps in the voltages - maybe the reference module itself is not that perfect.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 29, 2015, 11:12:12 am
I'll go to those steps later. You can see updated realtime datalog (http://xdevs.com/datalog_cal/).

What I understood from graph in post above , are indeed two things:
Having 5V formed by external resistors (even bad as 25ppm/K) now got 5V to behave with close coupling to temperature. Before we had only constant drift, which was way larger that any tempco deviations. Knowing this simplifies issue just to matter of dollars for stable resistor network.

Now, we go back original LTspice simplified circuit I shown before. -12v and +5v refs are derived from +12vref, remeber? And now since we have -12v and +5v "stabilized" almost all of that drift (~30ppm) comes from...ASICs resistors 6.0K and 4.14K, which we still have used from old deadbugged U180.

This morning I ditched ASIC allthogether and replaced 6K with 10K Fluke mica wirewound (3ppm/K) paralleled with 19K Vishay VHP (0.3ppm/K max) and 4.14K replaced with 5K Fluke wirewound mica (5ppm/K). This gives a tad higher 12.45, -12.45 and +5.15v ref levels, but should be no worries.

Anyone into business to get us 6-resistor network for ultimate performance? :)
I ordered 10k+10k hermetic vishay network from ebay to replace LT5400 (its absolute tempco is not so great). Will see how that goes.

All data is with NPLC10 btw. If levels stay stable (within 2ppm), we will switch for more accurate NPLC100 testing with proper resistor  wiring, single copper thermal anchor and no 40cm scancard wires hanging in the air all over the joint.

I might rewind few of 10k/50k fluke resistors to make 6.5k, 4k and 24k resistors. I have few 250k ones, but I don't think my soldering skills up to task to make resistor network with 0.01mm manganin wire...
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on November 29, 2015, 11:18:58 am
Hi TiN, I am not sure if you saw this thread of Andreas some time ago, a contributor Edwin Pettis added an interesting perspective of stability of resistors (selecting the ones with the TempCo you want).
https://www.eevblog.com/forum/projects/t-c-measurements-on-precision-resistors/ (https://www.eevblog.com/forum/projects/t-c-measurements-on-precision-resistors/)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 29, 2015, 11:41:41 am
Sure I saw it :) And here with this ADC rare example when both abs. Tempco and matching are needed. I'm not sure if Edwin will be up to 6-resistor network in few pieces qty.
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 29, 2015, 12:20:51 pm
The requirements for the resistors are not that high here. Especially there should be no need for all 6 resistors to be matched. This is 3 pairs of resistors, that can be treated seperately. The main issue is to have very good TC matching, especially with the 10K/10K pair. The absolute values are not at all critical and only the 1:1 ratio for the 10 K ones should be close. I see no problem if the others are a few percent off.
Also long term drift should not be an issue - the thing is to have less than 0.1 ppm over a day or so. It would not mater to have somthing like 20 ppm/year drift, as a ACAL should readjust for new vaues.

The other question is where the 5 V is actually needed for.  My guess is, it might be used for Ohms  - but the diagram will tell us. Depending on this the 5 V may not even be critical at all.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 29, 2015, 12:59:56 pm
I meant tempco and tempco matching. Resistance value is not that important, yes. Hopefully VPG hermetic network should do well.
Title: Re: Repair : Old rusty HP 3458A
Post by: Theboel on November 29, 2015, 01:50:59 pm
Sure I saw it :) And here with this ADC rare example when both abs. Tempco and matching are needed. I'm not sure if Edwin will be up to 6-resistor network in few pieces qty.

There is nothing wrong to ask
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on November 29, 2015, 02:57:16 pm
The other question is where the 5 V is actually needed for.
 My guess is, it might be used for Ohms  - but the diagram will tell us. Depending on this the 5 V may not even be critical at all.

The +5V reference provides the 'minor slope' currents +S1, -S4, +S16 and -S64, i.e. the residual A/D conversions. See hpj 4/89, page 12.
These are created a bit differently in practice in the 3458A, i.e. by the network R150-153, the 37k5 and 16k7 resistors inside the ASIC and R185 (3M)
 

The OHM circuitry creates its own +10V reference directly from the LTZ1000A output, by U400A, RP400 and then to 13.0V, 10.3V by U305 and RP300A/B/C/R310.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on November 29, 2015, 04:45:50 pm
Just for the minor slopes, the 5 V is less (e.g. by a factor of 100 or more) critical than the +-12 V. So these two resistors don't have to be the absolute best.

I am not sure the VPG series is the right choice as they are made for long term stability - something that is not needed here. The only critical parameter is TC matching.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 30, 2015, 03:01:47 am
(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/lttest.png)

-10ppm over 16 hours, -0.625ppm/hour

+12VREF,-12VREF stay around 1ppm stable. Perhaps time for 50K ASIC replacement?

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/50kasic.png)

I'm lucky to have few 50K mica fluke wirewounds suitable to task, I believe.

Also "jumps" are truly seem to come from LTZ (pink plot on graph, ZR_HI2-ZR_LO2 measurement). Perhaps ebay's 3458a A9 refs aren't all that good after all? :)
Title: Re: Repair : Old rusty HP 3458A
Post by: Vgkid on November 30, 2015, 04:17:51 am
Couldn't you just use a single 50k resistor instead of the (4) 50k resistors in series parallel annangement. Unless the 4 resistors are for a course adjust(currently i'm on my phone, clips is on my computer).
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on November 30, 2015, 01:28:47 pm
How many Fluke resistors should I put into 3458 to have it beat my K2001?  :-DD

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_flukeww_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/a3_flukeww.jpg)

+1 more today (50K instead of ASIC network).
Issue with all these external resistors is thermal constant is getting very large. Meaning that meter takes lot of time to get into stable state when all resistors get their working temperature.
Little internal ASIC network get hot really quick, but these big-ass 3W wirewounds are slow as snails. I'm still seeing 2-3ppm/minute warming up after 30 minutes.
Such DMMs need multiple hours of warmup time, so not a big deal, but definately making use/transport less "easy".
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 01, 2015, 05:00:01 am
Removed all wires to scan card (no monitoring), replaced integrating 330pF cap with new polypropylene one, shorted power supply for -12V opamp.
Nope, still doing it's pesky drift (this time up, +3.88ppm/hr).

Let's go extreme, make own resistor, as all those I have now are all over the place in terms of tempco or tempco matching (Fluke's 5ppm/K, Vishay 0.3ppm/K, RNC 25ppm/K), which is no good, given what HPJ says about resistor network:

(http://www.xdevs.com/doc/HP_Agilent_Keysight/3458A/test/adc_rnet.jpg)

I took one of my bad Fluke 156448 250K 0.05% 3ppm/K (https://dev.xdevs.com/attachments/965/FR-4148.jpg) and started adding taps. It's not a job for faint-hearted shaky-handy people, I can tell you that.  :rant: And forget of doing so without microscope. Resistor wire (manganin?) is not solderable, so I'm using single strand from copper AWG30 cable to hop around resistor body and fix it under tension with blobs of solder in strategic spots.
Trimming done by adjusting wire position on the edge, where it touches resistive wire. I hope this will make same tempco or at least close to that, as it is same resistive wire, on same mica holder.

If that works (which I don't quite believe, it's really tricky and touchy), I'll make hermetic nitrogen-filled can for it, to make it useful.

So far resistor sections archieved:

10.162K, 24.860K, 10.451K, 10.902K, 6.087K, 4.187K. I still have about half of resistor body left, so I'll make pair of 50K one on it as well.
Title: Re: Repair : Old rusty HP 3458A
Post by: Vgkid on December 01, 2015, 05:35:09 am
Looking forward to this impressive work. Just thinking about modifying those resistors  :phew:
Still mad at myself for not bidding on those resistors...
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on December 01, 2015, 06:38:43 am
Wow! I was just reading Edwin Pettis' history of wirewounds (http://www.edn.com/design/analog/4427151/The-last-half-century--Wirewound-resistors-Part-one) and the nightmare of trying to weld wires to them. Interesting to see that the Minuteman and Trident nukes, not to forget the Apollo spacecraft all had dodgy resistor leads  :o

Good luck with those wire taps TiN!  :-+
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 01, 2015, 06:54:15 pm
Test number "I lost the count already"

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/hpbodge_1.jpg) (http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/hpbodge.jpg)

I failed with 10K -12VREF network, but found my VPG Z202's 10K's instead  :P 80.6K PTF is just 25ppm to bring 5VREF back to ~5.3V (with 22K/10.14K it's 5.8V, bit high to my like).

With this contraption meter can't calibrate to 10V (10V applied reads 9.58V, I cal'd it to 9.75V readout, it failed, but constants get updated to get 9.75ish).
Value does not matter, all I need is to see how drift goes. If it's better by some miracle, then I can try more effort.
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on December 11, 2015, 11:50:28 pm
Is the dream dead or alive?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 12, 2015, 04:40:42 am
Dead-live. Did not do anything much since last week, just put in 10k+10k VPG resistor network on negative -12v reference, it still drifts.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 21, 2015, 04:25:45 am
I thought worth to give a little update:

Our member, ManateeMafia was kind to hook up his 3458A for stability/datalog test, so we spent some time to get it all working in realtime via Raspberry Pi GPIB + FTP + D3.js.
Data already being accumulated for over a week for first meter (red graph), a week for second (green graph) and bit over a day for third one (blue graph).

All three measuring same Fluke 732A 10V, and both ppm/dev and HP's temperature being logged.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/comp3458a.png)

As of my meter, it's getting downhill. I did not do anything for it over last 2 weeks, just sitting running 24/7 on shelf, and it began to throw ERR114 - multislope rundown convergence errors now (once every minute or two). Busy with other nuttery projects for now, will get back to it next year, when I get more time to waste.  :-/O
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 23, 2015, 06:03:26 pm
Alright , transplanted ASIC back to it's original second A3 PCB, started 10V 3245A test once again.
Also replaced AD848 and used new film 330pF C119 cap.

Good thing - AC issues are fixed now, it was A3 failing for SELFTEST ACDCV 10mV/100mV/1V.
Selftest pass now, CALd to 10V.

Will the evil machine drift? I'm ready to bet bottom dollar that it will....

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 25, 2015, 04:22:45 am
I wonder who got this one... (that's not me, I promise!   8))
eBay auction: #381500231334
Title: Re: Repair : Old rusty HP 3458A
Post by: nidlaX on December 25, 2015, 10:00:13 am
I wonder who got this one... (that's not me, I promise!   8))
eBay auction: #381500231334
I saw three "cheapos" come and go from express_test, but they are described as "incomplete" with no pictures of the actual units! :bullshit:
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on December 25, 2015, 10:41:40 am
I wonder who got this one... (that's not me, I promise!   8))
eBay auction: #381500231334

I saw that one and was tempted, then I recalled this thread and came to my senses.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 27, 2015, 07:39:02 am
Drifting bonanza continues...

Here's what done so far these days:

* Removed drifty U180 ASIC from original bodged up A3 PCB.
* Cleaned second A3 PCB with ASIC, replaced integrating cap to DK 399-7719-ND, installed new AD848
* Cleaned ASIC between legs with cotton swap and IPA
* Soldered in ASIC to A3

Tested stuff, ACDCV issues are gone now, meter pass selftest and calibrate okay.
1ppm jumps in readout were still there. As we tested this before, it was reference voltage jumping, so eyes to A9 PCBA (which I got from eBay, as some may remember).

* Added copper-foil hat around A9, thinking stray air-currents around A9 cause jumps.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/copperhat_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/copperhat.jpg)

* Proven useless, copper hats removed.
* Removed LTZ1000ACH
* Installed LTZ1000CH (1990) instead.
* Removed 95K resistor to get temperature setpoint back to +80°C

Since we talking sub-ppm now, I changed source at meters from HP 3245A 10V output to one of my LTZ1000-references (https://xdevs.com/article/kx-ref/) 7V output. Both K2001 and 3458 measuring same output. LTZ powered from K2400 12V ~30mA.

(http://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/test/test_ch.png) (https://xdevs.com/datalog_a3b/)

Now, no ppm jumps, only drift, at much slower rate ~0.2ppm/hour.

Funny part - LTZ1000CH non-A warms up much slower than original -A, this is visible by having 10V on meter and power it on from cold. Voltage creeps 3-4mV/second till it reference voltage stabilize after ~2 minutes.
If one try to run selftest or CAL 10V during this period - you will be greeted by HARDWARE FAULT 204: REFERENCE CONTROL LOOP FAILURE or something like this :) Once it warmed up, selftest and CAL works ok.

Could it be just leakage on ceramic surface of ASIC causing drift, all this time?  :-//

Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on December 27, 2015, 10:46:02 am
Leakage on the ceramics is a possibliliy. As the level of leakage is likely not stable this my look like bad resistors and cause quite some drift. However it takes quite some leakage to disturb the 10K/10K voltage inverter.

Even when resonable clean, it may need a little for the ASIC (together with board) to warm up - In the warm state surface water layers evaporate and reduce leakage. It might a good idea to have critical parts run slightly warm, e.g. 10 degrees above normal ambinet, just to reduce leakage. So it might not be the LTZ1000 that needs the longer warmup, but the ASIC.  In the initial phase there can also be larger thermal gradients on the board. I would not trust the ACAL very much thats done so fast after turn on.

For the ceramics is might be a good idea to wash it with clean water too - some of the dirt (e.g. salts) might be better soluble on water than IPA.
Title: Re: Repair : Old rusty HP 3458A
Post by: acbern on December 27, 2015, 11:16:45 am
Or the non-A LTZ you soldered in is drifty!?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 27, 2015, 11:39:38 am
However it takes quite some leakage to disturb the 10K/10K voltage inverter.

Even with inverter voltages stable (via external resistors) it was still drifting about same rate or worse. There are still other both analog and digital signals around ASIC involved.

Quote
So it might not be the LTZ1000 that needs the longer warmup, but the ASIC.  In the initial phase there can also be larger thermal gradients on the board.
Did day worth test before with original A9, did not see this warmup effects so long before.

Quote
I would not trust the ACAL very much thats done so fast after turn on.
It was just sanity test, to check if other issues raised in process, not by any means meaningful calibrations.

Quote
For the ceramics is might be a good idea to wash it with clean water too - some of the dirt (e.g. salts) might be better soluble on water than IPA.
Will try it. I noticed purple residue (same color of ceramic) on swab after cleaning. I thought that should not be there.

Quote from: acbern
Or the non-A LTZ you soldered in is drifty!?

Let me check it.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 27, 2015, 12:51:23 pm
Hooked my LTZ module output to reference input on 3458A instead, so we can see both results.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/test_extref.png)

K2001 reading this reference voltage
3458 reading 3245's 10V output

I need more meters around  :)
Title: Re: Repair : Old rusty HP 3458A
Post by: branadic on December 27, 2015, 07:19:20 pm
Quote
Could it be just leakage on ceramic surface of ASIC causing drift, all this time?

Not necessarily leakage. I was told by a representative from IST AG, that ceramic is also somewhat conducting and with increasing temperature the conductivity rises, thus limiting the maximum temperature for platinum sensors. For higher temperature application an additional insulating layer is required.
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on December 27, 2015, 07:34:04 pm
Quote
Could it be just leakage on ceramic surface of ASIC causing drift, all this time?

Not necessarily leakage. I was told by a representative from IST AG, that ceramic is also somewhat conducting and with increasing temperature the conductivity rises, thus limiting the maximum temperature for platinum sensors. For higher temperature application an additional insulating layer is required.

Ceramic is conduction at much higher temperatures than temperatures below 400K.
Title: Re: Repair : Old rusty HP 3458A
Post by: branadic on December 28, 2015, 10:46:54 am
Quote
Ceramic is conduction at much higher temperatures than temperatures below 400K.

No, there is conductivity right below 400K, but it becomes more critical as temperature increases.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 28, 2015, 01:23:48 pm
Hm, it drift down over today logging, at same rate ~0.2ppm/hr. Is it because meter was upside down (as i cleaned A3 again) and electrons fall off LTZ1000 chip? :)

Turned it back with face up, lol.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on December 28, 2015, 04:10:45 pm
Turn it on its side - it will balance out!  :-DD
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 28, 2015, 04:33:40 pm
Perhaps in other life...

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/test_d2.png)
Title: Re: Repair : Old rusty HP 3458A
Post by: Kleinstein on December 28, 2015, 05:05:38 pm
Though the temperature does not change that much, there seems to be a correlation from the drift of the 3458 reading and temperature. It might be worth doing a test with intentional larger change in temperature if the drift is really a temperaure effect.

Modereate heating (e.g. 40-50 C) of the ASIC could be an option to see if this temperature is the critical one. It might even reduce leakage from surface water films on contaminated ceramics.
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on December 28, 2015, 08:19:54 pm
TiN, A really dumb thought, please tell me if you have checked this out before, the method of 'dual / multislope' ADC relies on a good frequency source, the variability/drift changing with position made me think about crystals, how their resonant frequency changes with position. It couldn't be  bad crystal could it????????????
Title: Re: Repair : Old rusty HP 3458A
Post by: lukier on December 28, 2015, 09:01:54 pm
I've mentioned that a month ago in post #423, so probably it was ruled out.

Although, it would be quite funny if the drift can be traced to the crystal. It should be ratiometric in principle, but imagine that the physical time for run-up and run-down (not the crystal oscillation count) was different between reference calibration and when taking measurements.
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on December 28, 2015, 09:17:49 pm
Don't give TiN any ideas. Next thing you know, he will have it Rubidium powered. Atomic 3458A.
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on December 28, 2015, 09:30:09 pm
Don't give TiN any ideas. Next thing you know, he will have it Rubidium powered. Atomic 3458A.
LOOL, but if I remember it correctly it was TiN original idea to make KX Calibrator.
So it will be also frequency standard and not only voltage/current/resistance :)
Fingers crossed for 3458A repair.
Another one  on ebay for low price http://www.ebay.com/itm/141862586249 (http://www.ebay.com/itm/141862586249)
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on December 28, 2015, 11:32:55 pm
@lukier, thanks, missed that one!
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on December 29, 2015, 12:41:09 am
TiN, A really dumb thought, please tell me if you have checked this out before, the method of 'dual / multislope' ADC relies on a good frequency source, the variability/drift changing with position made me think about crystals, how their resonant frequency changes with position. It couldn't be  bad crystal could it????????????

Tried that long ago :)
Title: Re: Repair : Old rusty HP 3458A
Post by: cncjerry on January 06, 2016, 01:11:40 am
By the way, there is a nice looking 3458a for sale in the San Francisco Bay Area on craigslist. Not mine, of course. Opening price was $2,900 and the person dropped it to $1,950 last night.  Says it passes self test, all the buttons work :-//.  I was kicking it around but I have way, way too many meters already.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 06, 2016, 01:45:42 am
Get it, you will never stop to amaze how much time and effort this beast can steal from you ;).
If you get lucky, than you may end up with working reference meter, which you can calibrate all your gear to.
If not, we will see 30 pages of debug and repair, like above  :-X
Title: Re: Repair : Old rusty HP 3458A
Post by: cncjerry on January 06, 2016, 03:21:51 am
Get it, you will never stop to amaze how much time and effort this beast can steal from you ;).
If you get lucky, than you may end up with working reference meter, which you can calibrate all your gear to.
If not, we will see 30 pages of debug and repair, like above  :-X

This is/was my concern.  I was seriously thinking about it but then I just spent about 20hrs debugging one of my 3457a meters.  When I read thru the theory of ops on the 3457a, I quickly realized that subtle problems (let alone the drift as illustrated in the 3458a above) could be a real bear to fix, if ever.   The 3457a has separate circuitry to eliminate the effect of 10pf of stray capacitance in the input amplifier, a separate offset DAC to control offset voltages throughout the meter, etc.  My meter calibrated perfectly, showed no errors until I hit autocal, hell, I didn’t even know it was broken! But didn't someone say for like $2300 Agilent would take your old3458a, fix, calibrate and send it back almost like new?  So for $4,300 you would have a 20yr old meter that could break again at any time requiring another $2,300.  I don't know, I guess these meters are out of my league.
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on January 06, 2016, 03:37:03 am
Kind of seems like they are showing there age as well - after 20 years stuff drifts. There are an awful lot of broken ones for sale these days.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 06, 2016, 04:40:13 am
I'm sorta disagree at last point. 20 years stuff is already drifted most of it's stress out, so it is _usual_ to have older meters being more stable. Of course that does not apply to parts like capacitors (which degrade with age) or connectors/keys/displays, but real important stuff in 3458 and other hi-end meters usually properly guarded or designed in a way to minimize those drifts. Caps are easy to replace, so with bit of knowledge, it's possible to get good device, given all important stuff is good. One of latest service notes for 3458A actually does imply that newer meters had excessive drift issue, as newer parts may be not as tightly manufactured as older ones.

In any case you will learn a hell lot about these sensitive designs in case  your meter go wank or need repair. Even with all shenanigans described above, I learned more in these 200 hours spent than few years messing with Keithley 2001's (which are meter of itself already to start with). This also goes far beyond repair itself, but also how to produce stable enough signals and references to test it, how to maintain proper wiring and connections, how change in ambient temperature affects parts and so on, it goes and goes. I don't regret on this project, even though it makes me angry half of time I touch it. It's worth those $$ spent.

Also I don't think it's fair idea to send self-repaired and bodged up units to Agilent to repair. As they cannot guarantee by any means that parts you changed by yourself will meet specs/reliability requirements they have for it, so it may just be as simple as replace all affected PCBA's, which would cost way more than calibration fee. That will also prevent you from going into unit again, which sorta kills lot of learning right here. So, no, I'll not send mine to official calibration, it's not worth that. Would be more interesting (and way more useful!) to build and calibrate 10V/10k references and make generator suitable for SCAL.
Title: Re: Repair : Old rusty HP 3458A
Post by: TheSteve on January 06, 2016, 04:50:02 am
TiN - I understand what you are saying, many older parts do drift less as they age. But as you say not all parts age gracefully, especially capacitors and such. For a project the 3458A may offer a great learning opportunity but it comes at a pretty high $ cost. It may also be the ASIC in them that is failing. I am sure HP/Agilent sold quite a few 3458's but the number parts units on ebay still concerns me. If I had no budget I'd certainly have one or more of them :)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 06, 2016, 05:07:44 am
What you say equally applies for any 7.5 and 8.5 meter. And I agree, these are not for faint heart. But benefit of old meters is that lot of voltnuts have them (and can help on cross testing, learning, etc). It's old school gear, meaning no BGAs, no linux, no megabytes of firmwares. Yes, there are few ASICs, but it's still workable in a way. Also service data and schematics are big plus. Take modern 34470 or 7510, if one get faulty, repair wouldn't be cheaper or easier.

And lets face, this is hobby for fun and selfeducation. If I really needed ppm-level measurements, than even my drifty ASIC would be lesser evil, as it have constant rate and can be compensated by post processing. Some people spent funds on hiend DMMs, others collect scopes, thirds buy Caesium standards, and some just lay on the beach for weeks :)

P.s. why i sound like thats me who buying 3458A? :D
Title: Re: Repair : Old rusty HP 3458A
Post by: nidlaX on January 06, 2016, 11:13:39 am
http://www.ebay.com/itm/HP-Agilent-3458A-Parts-8-1-2-Digital-Multimeter-Parts-Unit-AS-IS-/141869789909 (http://www.ebay.com/itm/HP-Agilent-3458A-Parts-8-1-2-Digital-Multimeter-Parts-Unit-AS-IS-/141869789909)

Wow! They tried to get away with selling this shit using just a stock photo? That's unbelievable! :palm: :bullshit:
Title: Re: Repair : Old rusty HP 3458A
Post by: Jwalling on January 06, 2016, 11:17:38 am
http://www.ebay.com/itm/HP-Agilent-3458A-Parts-8-1-2-Digital-Multimeter-Parts-Unit-AS-IS-/141869789909 (http://www.ebay.com/itm/HP-Agilent-3458A-Parts-8-1-2-Digital-Multimeter-Parts-Unit-AS-IS-/141869789909)

Wow! They tried to get away with selling this shit using just a stock photo? That's unbelievable! :palm: :bullshit:

Gotta love that one! "The item may have some signs of cosmetic wear, but is fully operational and functions as intended." countered by "**Parts Unit/AS-IS, note units are not complete before ordering**" and then "Guaranteed Working"  :palm:

Make up your mind, you moron! I hate sellers like this...

Jay
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 06, 2016, 12:32:33 pm
Can't believe there are obviously boards and other components missing - in fact the cases could be pretty much empty! Would be much better if they opened up the cases to show what they are really selling. Maybe these guys are dead lazy or maybe they don't actually want you to see what's in the box.

I'm constantly amused by a regular eBay ad for a Mont Blanc pen BOX - which is on for the same amount that I paid for the new pen. Also the ads for stuff which I can get much cheaper from Farnell! :)

Alan
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 06, 2016, 03:02:48 pm
That's part of their marketing plan to keep your attention crisp, eh?
I think bottom one does not have front panel PCBA either...
Title: Re: Repair : Old rusty HP 3458A
Post by: cncjerry on January 06, 2016, 03:44:31 pm
I think the units on craigslist are sketchier.  People have a little recourse on ebay whereas on craigslist pretty much all sales are final. I've seen items pilfered from work (Advantest spec analyzer, Tek tds744a) and serial numbers scratched off (tektronix 3054b), etc on craigslist.  Also, it looks like someone bought the 3458a locally as it is off the list.
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 06, 2016, 07:42:04 pm
Hey TiN,

I've been doing some cals of 3245A and K2000 using a 3458A which I believe has a good cal and also a cal on a 3458A that seems to have a dodgy cal even though its SRAM was fine. That led me to observe the drift on those items in an informal way. My observation was that the 3245A / K2000 combination seemed rock solid with only 1 digit variation over a day and a fair few degrees of temperature change. The two 3458As seemed noticeably more drifty with temperature (maybe twice as much) even if you only observed 6.5 digits. So I'm wondering whether you're just seeing normal temperature drift on your unit?

I'm musing over some tests which several people could run in parallel where a few units are tracked over a 24h period together with internal temperature, ambient and maybe the temperature of the key parts ref, asic etc (using a couple of thermocouples and a K2000 for instance). With some deliberate temperature variations thrown in that would allow some measures of correlation between ambient/internal temperature and reading to compare against the specs and also a sense of how much temperature variation each component exhibits as a function of ambient. We would need a fairly similar testing set-up so the results could be compared, of course. Not sure what's going on below but this kind of thing with more traces and data allowing some correlation calcs?

Regards, Alan

(http://anagram.net/nuts/MeterNoiseFloor/Images/3458A%20vs%203245A.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: Jwalling on January 06, 2016, 07:58:10 pm
http://www.ebay.com/itm/HP-Agilent-3458A-Parts-8-1-2-Digital-Multimeter-Parts-Unit-AS-IS-/141869789909 (http://www.ebay.com/itm/HP-Agilent-3458A-Parts-8-1-2-Digital-Multimeter-Parts-Unit-AS-IS-/141869789909)

Wow! They tried to get away with selling this shit using just a stock photo? That's unbelievable! :palm: :bullshit:

Looks like it sold! Although Ebay says it sold for "best offer accepted" which would imply that it sold for less, Watchcount http://www.watchcount.com (http://www.watchcount.com) says it sold for $995 which was the asking price.
Is Watchcount broken?  :-//

EDIT: Now Watchcount has a link to Ebay which is stating that it sold for $456 USD. Weird - it just changed in the last few minutes!

EDIT #2: Aha! the link from Watchcount points to the Ebay UK website! I wonder if you can get the best offer price by going through the UK site for everything??  :)

Jay
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 06, 2016, 08:38:07 pm
Madness...

BTW the 3458A clearly knows the internal temperature to better than 0.1C (e.g. the numbers saved in the calram) - anyone know how to get a higher resolution value out?
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on January 06, 2016, 09:31:24 pm
@Alan

I have been monitoring four different 3458A's recently using a RPi and an Agilent 82357b adapter. The ambient temperature, RH, and pressure have been monitored with one of these ... https://www.adafruit.com/products/2652 (https://www.adafruit.com/products/2652) Not the most accurate sensor but it is close enough for relative measurements. There has been a correlation with room temp and drift of the readings. TiN posted some results not that long ago but I am not sure if the sensor readings were included. Most of the time the readings did return to normal as room temperature changed. Unfortunately, the RPi seems to want to stop communicating through the USB ports regardless of the python script being restarted and the adapter getting hot plugged. I have some long periods of data, but the most recent meter has been an issue. I have ordered an externally powered usb hub and I hope this will fix it. It will be nice to show how a couple of these meters had excessive drift after being unpowered for a few months and then they seemed to settle down.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on January 06, 2016, 10:05:31 pm
I think, that I've shown this stability measurement already.

3458A NPLC100, over 35h vs. an LTZ1000, 25k samples.
ppm of mean LTZ1000 value, i.e. related to 7.162..V
No ACAL in between, but small temperature variation only and no EMC disturbance in our basement.

A fine 3458A and also a LTZ1000 reference are well capable of < 0.2ppm drift stability on that timescale, and < 0.04ppm of noise.

A resolution of 0.1°C is sufficient for that.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 07, 2016, 04:18:39 am
Hi Alan,

No, issue I have is not temperature drift. I spent days to make sure of it. And I'm very confident it's not drift of A9 LTZ reference output or something on A1 DC PCBA either.
I did left it drifting for few days before, and it had constant rate, going over 20ppm off, which is over any possible spec. K2001 connected to same source was showing stability in ppm level.

Anyhow, ManateeMafia had multiple 3458A's sampling 10V, and I finally got ahold to tidy-up and make page with summary graphs - 4 x HP3458A test of Fluke 732B (https://xdevs.com/datalog_comp/). It's permalink https://xdevs.com/datalog_comp/, (https://xdevs.com/datalog_comp/,) updated in realtime every 5 minutes, as new data comes in.

There are two caveats before you can study data graphs:

1. Sometimes data CSV's had delays, but graph shows as interpolated line between. For example there is no data at December 31, but line is there.
2. Time/date scale axis is not same on all graphs (as different meters were added into measurement at different days)

I don't know JavaScript or D3.js to figure how to fix these issues at this moment, so you warned :)

Lessons I've learn't so far from data:

Meter 04188 have drift +0.066ppm/day and tempco +0.066ppm/K
Meter 08451 (with real 002 option) have drift +0.145ppm/day and tempco -0.266ppm/K
Meter 01527 have drift or tempco 4ppm/day?. Not enough data to be sure (only 2 days history so far)
Meter 02157 with repaired A3 ADC have drift -0.05ppm/day and tempco -0.266ppm/K
Meter 02157 with good A3 ADC have very low drift (not much data to say for sure). Note finer ppm scale

I think this is very good data to answer question how good stability 3458A should look like...
Humidity, pressure and ambient temperature are also logged by standalone sensor hooked to same Pi, so you can nit-pick if there is any relation...

(http://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/datalog_jan_7_1.png) (https://xdevs.com/datalog_comp/)

Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on January 07, 2016, 07:05:35 am
TiN,
are all these measurements over several days done without ACAL DCV in between?

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 07, 2016, 07:11:35 am
That's correct, no ACAL anywhere.

P.S. Caveat with date scales fixed, now all X-axis on all graphs uniform!
P.P.S. Patched my nginx configs so CSV-files are served GZIPped now, page should load 2-3 times quicker (It's about 15MB of text data).
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 09, 2016, 12:02:39 pm
Hi Guys,

Apologies have been busy on something else :)

DrF - If you use a big enough averaging interval you will, of course, remove all noise in the limit - isn't this is just the hardware/software equivalent of a LPF. As you mentioned before, you might have to measure noise in a way that doesn't pick up drift also. I chose 2 nplc because I wanted to pick up the DC-10Hz noise. Re temp resolution at 0.1C - for any reading you can always scrape information out of the 'quantisation noise' but it would be helpful if the unnecessary noise wasn't there in the first place.

MM - That's a pretty interesting test - are you planning to run the correlations and try and unpick the temperature / time / pressure / humidity coefficients? These are all relative to the Fluke i.e. assuming the Fluke is fully stable?

TiN -  Re 20ppm - I didn't realise the drift on the 'evil' meter was quite that high. In a sense - as it is so high it should make it easier to find. Did you eyeball the temp/drift coefficients for the 4x3458As or run some regressions?

Did anyone figure out how/where the 3458A internal temperature is measured? I'm still thinking some controlled tests on tempco would be interesting i.e. making deliberate changes in ambient and getting an accurate feel for the tempco so it can be taken out of the time drift calc. I see the spec suggests 0.5ppm per day and also 0.5ppm per C for 10V which suggests MMs meters are well within spec - except maybe for #01527 and maybe it will also turn out good.

A.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 09, 2016, 12:21:52 pm
Temp sensor is plain LM35DZ in TO92 located on front left side of A1 PCB, routed thru digital mux and K6 relay to ADC.
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 09, 2016, 12:33:10 pm
Thanks, I see - U21. You have probably figured out what this is too :)

(http://anagram.net/nuts/Misc/Images/3458A%20A2%20thingy.JPG)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 09, 2016, 02:34:52 pm
Track&Hold capacitor for ACV. It's shown on schematics as well.
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 10, 2016, 06:42:24 pm
Ah yes, not a delay line or an inductor as it only has one end nailed down :)

For #08451 I'm getting these rough results as individual simple linear regressions. For the second set, I took the time drift out and tried the other factors again. Results (for the simple linear model) suggest no significance on anything except time drift.

BTW regressing internal temp vs. external temp gets:

internal = external * 66% + 19.4C (with R squared = 65%)

I guess that says something about the 3458A temperature regulation characteristics.

A.

(http://anagram.net/nuts/MeterDrift/Images/3458A-08451 drift.jpg)

Results are here: http://anagram.net/nuts/MeterDrift/10v_3458_nplc200_mm_08451_opt002.htm (http://anagram.net/nuts/MeterDrift/10v_3458_nplc200_mm_08451_opt002.htm)

Analysis is here: http://anagram.net/nuts/MeterDrift/10v_3458_nplc200_mm_08451_opt002.xlsx (http://anagram.net/nuts/MeterDrift/10v_3458_nplc200_mm_08451_opt002.xlsx)
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on January 10, 2016, 07:31:22 pm
Hi Guys,

..
DrF - If you use a big enough averaging interval you will, of course, remove all noise in the limit - isn't this is just the hardware/software equivalent of a LPF. As you mentioned before, you might have to measure noise in a way that doesn't pick up drift also. I chose 2 nplc because I wanted to pick up the DC-10Hz noise. Re temp resolution at 0.1C - for any reading you can always scrape information out of the 'quantisation noise' but it would be helpful if the unnecessary noise wasn't there in the first place.

...A.

It was not the noise that was in question here.
The noise parameter of the 3458A is covered by TiNs - zero input - noise measurement project, about the LTZ100s noise would be interesting also.

No, the question HERE was about timely stability, and I think I have answered that exactly and straight forward

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 13, 2016, 01:19:40 am
Here we go (https://www.youtube.com/watch?v=A4M7M32CLJk)

Next step...

So far it's good (https://xdevs.com/datalog_a3c/). Let's see if it stays that way next days.  :-DMM
Title: Re: Repair : Old rusty HP 3458A
Post by: ManateeMafia on January 13, 2016, 02:08:08 am
The phoenix has risen, again. Looking forward to seeing some good readings. I don't suppose you have a way to monitor the environment?  ::)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 13, 2016, 04:20:24 am
I need to overclock my hours to 48 a day at least. Will hook sensor to Pi tonight to add PTH data as well.

So far tempco non-measureable, and reading stay within 0.1ppm window over last 8 hours (averaged).
Interesting thing, I added my data into overall graphs, and it's easy to see 3245A's low-frequency oscillation, compared to way more stable 732B output.

(https://www.eevblog.com/forum/repair/repair-old-rusty-hp-3458a/?action=dlattach;attach=193400)

Time scale is matched.
It's time to make LTZ-based 10V source then.  >:D
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 14, 2016, 02:28:36 pm
Well congrats, nice job :)

The 3245A wobble is strange - I added a moving average to my 3245/3458 drift/noise measure above and updated the graph in the post to try and show any similar wobble (Excel is dumb and puts on a trailing moving av. instead of a centered one.) I can't see one.

Any final theroies what was wrong with the old A3?

A.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 14, 2016, 02:52:29 pm
That graph already with averaging.
I think it's something in lab coupling to meter. We talking fractions of ppm now. Life is not easy in that range...

No theories, old A3 have U180 hybrid asic drifting.
I have few ideas for it, but will do it later.

I hope to get my VISA fixed on PC tomorrow, so I can finally run your app for 3245+3458A. Really want to compare your results with mine.
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 16, 2016, 04:03:19 pm
Don't suppose the wobble could be linked to mains frequency? In the meantime FYI:

(http://anagram.net/nuts/3458A/Images/3458A%20start%20from%20cold.jpg)

That's with the source well warmed up beforehand. So 1.5h for 1ppm of eventual reading. For the last couple of hours of that test the tempco was +0.4ppm / C.

A.
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 18, 2016, 09:47:20 pm
And apropos of nothing (except it's more drift data) data for an Advantest R6144. Drift is apparently:

+3ppm per day
+0.4ppm / C
+0.26ppm / Hz

Total R-squared is 96%.

(http://anagram.net/nuts/R6144/Images/R6144%20drift%20and%20noise.jpg)

Analysis is here:

http://anagram.net/nuts/R6144/HP3458A%20driftandnoise%202016-01-15%2018-19-43.xlsx (http://anagram.net/nuts/R6144/HP3458A%20driftandnoise%202016-01-15%2018-19-43.xlsx)

I don't remember enough regression stuff to figure out how relevant the last two variables are.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 19, 2016, 04:17:09 am
Hi Alan,

Can you also measure 3245 set at +2.5VDC over 4-5 hours?
I saw some strange stuff, like drift up ~0.5ppm/hour. EDC MV106 2.5VDC was stable, so it's was not 3458.

Also seems like LTZ1000CH I have now in A9 still have shot pink noise, ~0.3ppm jumps. I'd expect all zeners have this popcorn noise, but some smaller than others.
I don't really want binning LTZ craze, so will look into other possible solutions, like zener current change maybe.
Need add probe to measure LTZ output directly, to be sure though.
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 19, 2016, 12:02:24 pm
Sure will do.

A.
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on January 23, 2016, 05:42:16 pm
>>> Can you also measure 3245 set at +2.5VDC over 4-5 hours?

OK (this is all ppm of 2.5V):

+0.8ppm per day
+1.1ppm / C
-0.41ppm / Hz (note minus sign)

Total R-squared is 90%. Noticeably more noise than R6144 (0.89ppm compared with 0.13) - although the R6144 was at 10V. A couple of things occurred to me:

+ not sure why you chose 2.5V but I guess close to ref voltage we're getting noise of ref plus dac, amplifier etc, close to 0V we're getting noise of amplifier mostly, some dac, no ref?

+ apologies I don't remember in which of these threads and exactly who suggested vlf fft - but talking to a mate here today - that sounds interesting as drift could be partly thought of as vlf 1/f noise, so a fft characterisation might be interesting?

>>> I saw some strange stuff, like drift up ~0.5ppm/hour.

Well part of the graph below shows e.g. drift of ~0.8ppm over 2h (from 10am 'til noon) so depending on the tempco of the EDC and the temp change over the measuring period, maybe that's possible? What ref does the EDC use?

(http://anagram.net/nuts/3245A/Images/3245A%20drift%20and%20noise%20at%202.5V.png)

Analysis is here:

http://anagram.net/nuts/3245A/HP3245A driftandnoise 2016-01-20 21-06-24.xlsx (http://anagram.net/nuts/3245A/HP3245A driftandnoise 2016-01-20 21-06-24.xlsx)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on January 23, 2016, 07:10:55 pm
Thanks, I see no drift on your with constant temperature, that's what I needed.
EDC using selected zener diode (1N829 or similar, TC-compensated), and it showed ~1.1ppm/C before, but question is not about it, it's about 3245.

2.5V output was due to my current experiment needs, since I was trying to use 3245A as stable DC source, but discovered that reading going up and up.
on 10V it's stable as this data suggests (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/test/kkh1.png)

Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on March 07, 2016, 05:37:13 pm
Everyone forget about this thread already, eh?

I had the machine running 24/7 last 2 months, and last few weeks temps were going higher and higher. Yesterday was really sunny day, ambient in the room reached +30°C, and meter TEMP? output peaked at +46C. Yikes, that's bit too hot, especially due to my A9 reference running with lowered temp.

I moved meter other shelf, and in process of doing so, checked fan filter.. I just cleaned it in january.
Photos better than any words:

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan_2m_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan_2m.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan_cln_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/fan_cln.jpg)

Moral of the story? Keep you 8.5-digit DMMs clean, or all your ppm's would run away....
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on March 07, 2016, 07:52:23 pm
That's what confuses me at the most HP/Agilent tools. The fan sucks outside air into the tool (inclding all potential dirt). The filter is nice, but not protective at that size of the mash.
Anybode ever thought of changing the FAN direction to blow out the air?
BR
PeLuLe
Title: Re: Repair : Old rusty HP 3458A
Post by: PA0PBZ on March 07, 2016, 08:24:50 pm
Anybode ever thought of changing the FAN direction to blow out the air?

So the dirt will enter all the other (unfiltered) openings in the case?
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on March 07, 2016, 08:33:25 pm
What about actively cooling the top and bottom covers with water pipeline and use fan for internal air circulation only?
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on March 08, 2016, 09:22:45 am
How about temperature management of the biological in the room? 30C for a human is too hot for a work environment. Cool the room, the human and the 3458.
A few bits of test gear , a PC will add to thermal stress for all. (HIHI)
Title: Re: Repair : Old rusty HP 3458A
Post by: alanambrose on March 08, 2016, 09:56:19 am
Actually I don't think the filter does that bad a job. My ~25 year old meters are very clean inside. There could be scope for a more intelligent fan control though to reduce the overall meter tempco - I'm getting +-0.3 ppm/K (see image below).

TiN - was the LTZ ref that you put in the 3245a conditioned already? - I read in a 3458a service note that Agilent would recondition A9 boards by powering them up for for 6 weeks if they had been in the parts bin for too long. My drifty 3458a seems to have sorted itself out after leaving it on for 5 weeks already and updating the 8051 to V ,2.

MM - maybe this is worth trying for your drifty 3458a?

Note in the graphic below that the regression model (using all 3 factors - the biggest being tempco) gives a predicted reading very close to the actual reading - a fairly useful characterisation if you wanted to intelligently trim the 3458a.

A.

(http://anagram.net/nuts/MeterDrift/Images/732a%20vs%202x3458a.png)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on March 08, 2016, 10:03:20 am
Well, yes, filter does the job, just need to be cleaned periodically. It's not really an issue for stock 3458A's with their scorching A9's, but could be a problem for ones at lower thermostat point.

I had 3245A running for month or so 24/7 prior that measurement. I'll have to redo it again next time.

MM's meter (opt2) got sorted out as well, after about 2 weeks running, so that info about right.

P.s. i'm travelling atm, and with Murphy's law same time ISP borked IP mapping, so can't link any data just yet, sorry.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on March 08, 2016, 10:28:54 am

TiN - was the LTZ ref that you put in the 3245a conditioned already? - I read in a 3458a service note that Agilent would recondition A9 boards by powering them up for for 6 weeks if they had been in the parts bin for too long. My drifty 3458a seems to have sorted itself out after leaving it on for 5 weeks already and updating the 8051 to V ,2.

This effect only applies to the original HP references, running at 90°C.
As discussed in the Super-LTZ1000 blog, the LTZ probably encounters hysteresis effects at elevated temperatures, maybe higher than 70°C.

So, any pimped 3458A reference (100k in parallel to the 15k), or any DIY LTZ1000, running at 45..65°C, won't have this problem.

Keysight copied this problem into their 34470A reference, btw.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on March 08, 2016, 10:35:37 am
I still think that was a deliberate decision to favor industrial environment specs with +50 ambient and tight rack fill. During my repairs on K2001 I had RTD on current shunt not far from A/D and with chassis closed it gets to ~62C, and that's just unit sitting on the shelf.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on March 08, 2016, 10:59:18 am
I still think that was a deliberate decision to favor industrial environment specs with +50 ambient and tight rack fill. During my repairs on K2001 I had RTD on current shunt not far from A/D and with chassis closed it gets to ~62C, and that's just unit sitting on the shelf.

That's correct, calculation is: T(oven) = 55°C (Tamb)+ 10°C (A-version) + 13°C (Temp. rise inside 3458A) +10°C (Temp. rise in a rack) + 5°C (regulation margin).

Anyhow, the 3458A was originally promoted as a Metrology grade instrument, so they could have offered a metrology version with limited ambient temperature range of 15..35°C, like 732Bs and 8508As, and they could have used the non-A version, giving a max. oven temperature of 65°C, avoiding a lot of problems and making the reference much cheaper.

In the 34470A, the inner temperature is at least 10°C lower than in the 3458A, so they could have used an LTZ1000 at about 75°C, at 2ppm/yr. stability, quite easily.

But they just did not think new, obviously, they just copied.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on March 10, 2016, 07:14:41 pm
TiN donated the ASIC from drifting A3 board for extreme teardown.
Chip is now naked and ready for following actions.
Please post your areas of interest.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on March 10, 2016, 07:38:06 pm
Mm, minor correction, it's ASIC with Error 114, multislope convergence errors, the from first A/D board.

Looking forward for the photo p0rn :) Perhaps analog IC design guru's can tell us more once hires pics done.
Title: Re: Repair : Old rusty HP 3458A
Post by: chinapp on May 01, 2016, 02:31:04 pm
is there any news of the   ASIC research? i am keep watching ... :=\
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on May 13, 2016, 05:27:09 am
is there any news of the   ASIC research? i am keep watching ... :=\
Yep, it is in pipeline with LM399, MAB399 reference and waiting for LT-FLU. Stay tunned.

Someone interested, it looks like A1 board missing
http://www.ebay.com/itm/HP-Agilent-3458A-Digital-Multimeter-For-Parts-Only-As-Is-/162067493629?hash=item25bbf9b2fd:g:dCMAAOSwWntXM1Zr (http://www.ebay.com/itm/HP-Agilent-3458A-Digital-Multimeter-For-Parts-Only-As-Is-/162067493629?hash=item25bbf9b2fd:g:dCMAAOSwWntXM1Zr)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on May 13, 2016, 12:21:06 pm
Yah, now it will skyrocket in price :) no second 3458 for tin...
Title: Re: Repair : Old rusty HP 3458A
Post by: plesa on May 13, 2016, 06:18:02 pm
Yah, now it will skyrocket in price :) no second 3458 for tin...

We will see, A1 board isnt cheap at all. Look that meter is in good shape, if we can call it meter without A1:)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on May 18, 2016, 04:20:27 pm
Someone won it for rather high price at 1.6K. Perhaps EEVblog effect of posting a link here. If buyer have good A1 board and ready for some gamble it's still can be a worthy win, but these are big if's. Hopefully we may see a thread about it here or elsewhere.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on August 05, 2016, 06:32:53 pm
Rusty 3458 found it's glory. Ebay seller stolen my photo for the listing: http://www.ebay.com/itm/HP-Agilent-3458A-Digital-Multimeter-8-8-5-Digit-DMM-/262563138089?hash=item3d21fb8a29:g:AqsAAOSwnQhXo1zD (http://www.ebay.com/itm/HP-Agilent-3458A-Digital-Multimeter-8-8-5-Digit-DMM-/262563138089?hash=item3d21fb8a29:g:AqsAAOSwnQhXo1zD)
 :palm:
Drawback of not having watermarks all over the photos.  :rant:
Title: Re: Repair : Old rusty HP 3458A
Post by: pelule on August 05, 2016, 07:24:33 pm
As your pictures are high resolution and good quality, it may happen, if one searches for a pictures of a specifc gear on the web. :-//
And it tell's a lot regarding the quality of the gear offered... :--
But please do not stop your style of publishing  :-+ - a bunch of interest her.
PeLuLe
Title: Re: Repair : Old rusty HP 3458A
Post by: Monittosan on August 07, 2016, 11:56:56 pm
Rusty 3458 found it's glory. Ebay seller stolen my photo for the listing: http://www.ebay.com/itm/HP-Agilent-3458A-Digital-Multimeter-8-8-5-Digit-DMM-/262563138089?hash=item3d21fb8a29:g:AqsAAOSwnQhXo1zD (http://www.ebay.com/itm/HP-Agilent-3458A-Digital-Multimeter-8-8-5-Digit-DMM-/262563138089?hash=item3d21fb8a29:g:AqsAAOSwnQhXo1zD)
 :palm:
Drawback of not having watermarks all over the photos.  :rant:

His sold 4 of them in the past. I guess they where all from that lot?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 18, 2016, 12:31:50 pm
Hmm, what's going on here...

(https://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/mark/srams_1.jpg) (https://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/mark/srams.jpg) (https://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/mark/sramb_1.jpg) (https://doc.xdevs.com/doc/HP_Agilent_Keysight/3458A/mark/sramb.jpg)

 :o

(http://orig03.deviantart.net/690b/f/2014/359/f/a/custom_mtg__thyric_s_emblem___rhalenthia_set_by_etherwebz-d8b7au9.png)
Title: Re: Repair : Old rusty HP 3458A
Post by: Nuno_pt on October 18, 2016, 12:34:27 pm
Hmm, it smells like RAM/EEPROM's replacement. :D
Title: Re: Repair : Old rusty HP 3458A
Post by: ElektroQuark on October 18, 2016, 02:10:04 pm
A DIP14 swimming in an DIP 28.
Waiting for the "teardown"...
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 18, 2016, 02:44:50 pm
No, these are fresh new parts  :popcorn:
Title: Re: Repair : Old rusty HP 3458A
Post by: SeanB on October 18, 2016, 07:28:16 pm
DIP14 is the small CMOS memory controller made by Dallas, which is the heart of all those timekeeper and RAM modules. It is just there on one side of the PCB inside, with the other side having the 6116LP3 RAM and the RTC chip and then stacked over all this the small lithium primary cell and the backup cell if fitted. The chip does the power off function, switching Vcc and keeping all the enable pins in a correct state when power falls, so the RAM will not draw excess power during standby.
Title: Re: Repair : Old rusty HP 3458A
Post by: VK5RC on October 18, 2016, 11:37:53 pm
My 2 guesses
1Are you about to do some experimentation looking at the effect of different timing of the different models  of dallas nvram?
 I recall when looking for a  replacement for mine,  the original was hard to find,  ended up getting a few 'close'  ones,  I don't recall the part numbers now.
2 You are about to grind off the top and get to the lithium connections?
Robert
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 19, 2016, 04:21:31 am
No and no. You guys such savages  :-/O.

One local taiwanese volt-nut contacted me few days ago. After some challenging discussion with great help of google translate, it was determined that he has some nice gear, including a RAM-sick 3458A. So hopefully next month we will have a chance to meet and look on his 3458A, and perhaps get my 4920M calibrated. This is my best shot right now for AC calibration.  :'(
Title: Re: Repair : Old rusty HP 3458A
Post by: klaus11 on October 19, 2016, 05:32:25 am
A little help please, I need to know if this new firmware upgrade lose calibration data. From a very early version up to 8.2 example.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 19, 2016, 05:42:51 am
A little help please, I need to know if this new firmware upgrade lose calibration data. From a very early version up to 8.2 example.

No.

Frank
Title: Re: Repair : Old rusty HP 3458A
Post by: HighVoltage on October 19, 2016, 08:25:57 am
No and no. You guys such savages  :-/O.

One local taiwanese volt-nut contacted me few days ago. After some challenging discussion with great help of google translate, it was determined that he has some nice gear, including a RAM-sick 3458A. So hopefully next month we will have a chance to meet and look on his 3458A, and perhaps get my 4920M calibrated. This is my best shot right now for AC calibration.  :'(
How does fixing his 3458A help you to get your 4920M calibrated?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 19, 2016, 10:12:05 am
HighVoltage
That is to be determined. It's all I can say right now, sorry.  :bullshit:
Title: Re: Repair : Old rusty HP 3458A
Post by: klaus11 on October 19, 2016, 11:19:46 am
Another question, the Front / Rear button when pressed remains locked, or else you press and exits to stop pushing.
I need to know if so or is defective.
Title: Re: Repair : Old rusty HP 3458A
Post by: Dr. Frank on October 19, 2016, 11:45:21 am
Another question, the Front / Rear button when pressed remains locked, or else you press and exits to stop pushing.
I need to know if so or is defective.

That is a purely mechanical switch, therefore stays locked in either position.
If it flips out again, the locking spring/mechanism is defect.
Title: Re: Repair : Old rusty HP 3458A
Post by: klaus11 on October 19, 2016, 11:49:55 am
Thank DR. Frank, the conclusion is faulty.
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 26, 2016, 12:14:43 pm
I have a question to 3458A owners. Anyone was using non-10V/non-10K standards for calibration before?
Meter actually allow 1V - 12V for DCV and 1K to 12K for OHM, but also accept -0.9 to 0.9 values and -12 to -1V, which makes me thinking :)

If I understand correctly, less than 10V/10K would compromise adjustment, as measurement value is more suspected by noise floor limit, reducing SNR and absolute accuracy precision. That's clear more or less.

But how about -10V calibration? Anyone tried? :)
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 27, 2016, 02:52:58 am
If I understand correctly, less than 10V/10K would compromise adjustment, as measurement value is more suspected by noise floor limit, reducing SNR and absolute accuracy precision. That's clear more or less.

But how about -10V calibration? Anyone tried? :)

You can always take a backup of your SRAM and then try your experiment surely?  ;)

I have to admit when adjusting the cal of my Keithley 2015 I have merely swapped the +/- leads around when doing the +10V and -10V DC cal. I'm sure I should be shot down as a heretic for this even though I allowed a few minutes for the lead swap to settle any thermals?
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on October 27, 2016, 04:09:47 am
Quote
You can always take a backup of your SRAM and then try your experiment surely?

Aha, A5 CPU board is on it's way already.  :popcorn:

Quote
I'm sure I should be shot down as a heretic for this even though I allowed a few minutes for the lead swap to settle any thermals?

Why? That's what Fluke 5700A does as well, just swaps the signal with relay.
Title: Re: Repair : Old rusty HP 3458A
Post by: Macbeth on October 27, 2016, 07:27:43 pm
Why? That's what Fluke 5700A does as well, just swaps the signal with relay.
Ahh. I figured something more sophisticated like an actual dual rail supply +/- and using something like "lead compensation" too.

With the 3458A I was always under the impression that you only  ;) needed an an accurate +10V DC and a 10K ohm resistor for complete calibration, no need for a negative calibration at all. But from what you are saying any accurate source of a reasonable magnitude can be used as long as you tell the meter what it is measuring? Like with the Keithleys IIRC anything from 9.9V - 10.1V are acceptable. It seems the 3458A has much more leeway if it allows negative volts to be used as a calibration reference!
Title: Re: Repair : Old rusty HP 3458A
Post by: PA0PBZ on October 27, 2016, 08:08:31 pm
Interesting, my Datron 1081 insists on having both + and - on all the DC calibration steps.
Title: Re: Repair : Old rusty HP 3458A
Post by: View[+]Finder on December 27, 2017, 03:25:03 am
Re: reversing the filter HP3458A, HP3245A
1) Fans prefer having their 'low pressure' side in open air (vacuum is limited, but pressure isn't)
2) Filters work better when they have a little lint on them (the designers knew that)
3) Filter replacement on air entry is difficult if inside the case (someone has to do it)
4) the 'dirt' in the air is mostly human skin cells (get a HEPA filter for your lab)

Just some observations . . .
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on July 06, 2018, 05:02:24 am
Since so many questions about 3458A lately popping on forums, I think it's justified to revive this worklog thread.

Another reason is that I just finished initial calibration test, using yesterday calibrated 5700A (to standards which values I know sub-ppm (maybe  :popcorn:) ).

Calibration points performance report (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/cal/XCR_3458A_XDEVS_U1_JUL_6_2018.pdf) - non-traceable, using my calkit software.

Please keep in mind that verification specification is 24 hour, 95% with K=1.
It is NOT what usual accredited calibration lab data reports have.  ;)

This meter was DIY calibrated in January 2017. It was 24/7/365 since.
I'm happy with stability, no adjustment calibration is necessary. She is stable!  :box:

(https://xdevs.com/doc/Wavetek/7000/img/cal_5700_2.jpg) (https://xdevs.com/doc/Wavetek/7000/img/cal_5700b.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: Zucca on July 06, 2018, 06:44:55 am
Quote
95% with K=1

I don't know what to google, what does it means?  :-[ (Imbarassed)
Title: Re: Repair : Old rusty HP 3458A
Post by: TiN on July 06, 2018, 09:09:14 am
Confidence level is optimistic 95% (most of specs are confidence level 99%). K number is guardband ratio. I use own guardband , so this multiplier is not used in test reports.

  Most real calibration certificates are at K=2.
Title: Re: Repair : Old rusty HP 3458A
Post by: HighVoltage on July 06, 2018, 09:15:51 am
Quote
95% with K=1

I don't know what to google, what does it means?  :-[ (Imbarassed)
Read the beginners guide to uncertainties...
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on July 07, 2018, 12:29:29 pm
Since it's time to recalibrate my newer 3458A it is time to take some photos of the process.
This unit had long overdue needed replacement for front binding posts, so it will be received new replacement today (expensive connectors, ouch)

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_refub_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_refub.jpg)

It's pity that to replace front and rear terminal blocks you pretty much have to take apart whole inguard section, as there is no other way to gain access. Photo below also have rare sight of modified 3458A A9 reference for lower temperature and better annual drift.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_in_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_in.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_modltz_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_modltz.jpg)

And today living room looks like a little mess  :-DD.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_work_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_work.jpg)

Ignore the drill on background, it's there just for intimidation.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: martinr33 on July 08, 2018, 04:11:43 am
 I don't see the replacement keypad buttons in the new color...

(Keysight has them, but you have  to call as they are not on  the parts list - they only list the old color).
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on July 08, 2018, 06:37:07 am
I realized this yesterday, but it's no big deal :) Only trained volt-nut eye can pick a difference  :-DD
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: VK5RC on July 08, 2018, 10:52:30 am
Thank for the close up of the A9 reference - Just noted the 111 \$\Omega\$ resistor -I will need to look at other 03458-66509 - I have always assumed they all had 120  \$\Omega\$
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: Dr. Frank on July 08, 2018, 11:48:57 am
Sure, the 3458A reference has always 111 Ohm, as its temperature is 95°C, therefore the Ube is about 70mV lower than intended , so to maintain the nominal zener current, the resistor has to be lower than the nominal 120 Ohm, also.
By pimping the standard ref to 65°C (100k || 15k), this increases the zener current and decreases noise.
Maybe that's the reason, why my instrument seems to perform better than others in in the Noise Performance Testing, we've done a few years back.

Greetings from Madeira
Frank
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on July 18, 2018, 11:26:39 am
I got my rubber-bumper for 3458A. Looks kinda strange, what you guys think?

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_rubber_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_rubber.jpg)
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: Zucca on July 18, 2018, 11:53:03 am
Father:
Quote
There is a room in Taiwan full of expensive big and small toys. Hell expensive toys, with a lot of numbers and colored small lights creating an unique atmosphere.
In this room a russian man is always improving and fixing those toys.
Sometime he writes his incredible stories about chasing that failure or that strange ppm jump.
Few people in this world can understand him and his complicated games, but a lot of people just admire him for his passion and talent.
One day he even protected one of his favorite 8,5 DMM with a long and soft rubber-bumper.

The almost sleeping son looks at his dad with big eyes.

Father:
Quote
Yeah, it's too strange to be true. You are right.
Good night son, I tell you the rest of the story tomorrow.

I smoked too much, don't ask me what
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: hwj-d on July 18, 2018, 12:41:34 pm
Father:
Quote
There is a room in Taiwan full of expensive big and small toys. Hell expensive toys, with a lot of numbers and colored small lights creating an unique atmosphere.
In this room a russian man is always improving and fixing those toys.
Sometime he writes his incredible stories about chasing that failure or that strange ppm jump.
Few people in this world can understand him and his complicated games, but a lot of people just admire him for his passion and talent.
One day he even protected one of his favorite 8,5 DMM with a long and soft rubber-bumper.

The almost sleeping son looks at his dad with big eyes.

Father:
Quote
Yeah, it's too strange to be true. You are right.
Good night son, I tell you the rest of the story tomorrow.

I smoked too much, don't ask me what

 ;D ;D ;D ;D
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: Dr. Frank on July 18, 2018, 04:59:56 pm
I got my rubber-bumper for 3458A. Looks kinda strange, what you guys think?

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_rubber_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img_u2/3458b_rubber.jpg)

Looks like a stretched 34401A..

On mine I've got the handles, but your bumper handles with care ..  :-DD

Frank
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TheSteve on July 18, 2018, 05:46:49 pm
I don't think TiN really like that boot. I think he just put it on there to tease me. I have boots on nearly all my gear - even a Keithley 2400 has one. My 3458A's have rack handles though. With the boot on the 3458A it doesn't look like a serious piece of gear anymore.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on July 19, 2018, 04:06:02 am
If KS release 3458B (from Boot, get it?) which look like this (but black, I no doubt), you know where you saw it first  :box: .

I have rack handles for my 3458s too, but removed them to allow easier connection on posts.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: kj7e on July 19, 2018, 01:49:50 pm
Is there a boot on the rear as well?
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on July 19, 2018, 03:56:31 pm
Yes, why would I stop half way.  :P Rear boot fits perfectly there, no need to trim/remove feet like with front one.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on August 05, 2018, 12:53:11 pm
Post #3458 :)

Time fly, I was just dreaming about getting one 3458A not very long ago, and now have two, which need attention and minor service after nearly 2 years of 24/7 operation. Nothing serious, just clean the dust off and replace binding posts block. My newer box had posts useable but ugly, and older was fine just old. So I bought brand new terminal block (can't afford it if you asking) so I swapped it on older unit, while original front go to second unit rear and rear on that goes to front. Whole process took few evenings and recorded on short timelapse video. Enjoy :)

https://m.youtube.com/watch?v=Yc-4U0l5nx8 (https://m.youtube.com/watch?v=Yc-4U0l5nx8)

Title: Re: Repair worklog : Old rusty HP 3458A
Post by: Muxr on August 05, 2018, 06:35:50 pm
Nice work TiN! My 3458A is in need of a new front panel and the binding posts as well. I don't know if I missed it, but did you manage to order them from Keysight directly?
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: HighVoltage on August 07, 2018, 05:06:25 pm
Looking great, TiN
Do you still have the original VFD's installed in both instruments?
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on August 07, 2018, 05:18:47 pm
Yes. One is bit dimmer, but you wouldn't be able to tell unless both meters are next to each other.
I stopped caring about VFD brightness while ago, as mostly they used over GPIB, sitting in other room anyway.

Should try disconnect front panel board completely, maybe I can shove few 0.0x ppms of noise on readings?  ^-^.
57XX MFC front panel assembly goes to great lengths to shield the display PCBA from rest of the unit.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on August 08, 2018, 09:52:03 pm
Got DIY replacement metal shield for inguard A1 for second meter.

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diy_covers_i_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diy_covers_i.jpg)

Like a bought one :D

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diy_covers_t_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diy_covers_t.jpg)

Installed in unit 2:

(https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diy_cover_hp_1.jpg) (https://xdevs.com/doc/HP_Agilent_Keysight/3458A/img/diy_cover_hp.jpg)
Title: Re: Repair : Old rusty HP 3458A
Post by: nikonoid on October 21, 2018, 02:23:23 am
This forum and this thread specifically is a gift that keeps on giving!

I have 3458a with a 202 Slave Test Convergence error. Board swap with another repaired 3458a proved that A3 ADC board is at fault. Now this bad A3 board has seemingly identical symptoms as ManateeMafia's (quoted from this thread from 2015!).

EL2018CN is now ordered. Keeping my fingers crossed. 8)

Thank you TiN! Thank you MataneeMafia! Thank you everybody else for participation and valuable information!


3-4 years ago, one of the broken 3458A's I bought had a bad A3 board. Given the recent repairs and valuable info from TiN I thought I would give it another shot. All of the voltage checks were performed years ago, but I went ahead and did them again. This was a donor board as I had acquired a replacement from Agilent.

The board had a 202: Slave Test Convergence error. Based on TiN's recommendation, I went through the ZR_LO and ZR_HI inputs from the A9 reference board. Then I went through the +12ref, -12ref, and +5ref to confirm they were working.

I checked the Reset lines and clock to the 8051 (U220). That looked good.

TiN had mentioned the TARM command during his repair that I didn't previously try. Using the command, I watched the outputs of pin 6 (OUT) briefly change on U110,U111,U112, and U140. So far so good.
When I got to U142, I could see the negative transition on the input, but the output never changed from +4.2V. After testing it a couple of times, I decided to replace U142 and fired up the 3458A.

The meter came up and was reading DC. Self-test and ACAL DC successfully.

The EL2018CN was sourced from UTSource .

Thank you TiN and all the others that have added to this thread. :-+ . Next step, repair defective A2 board with EL2039 from the same seller.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on October 21, 2018, 03:05:33 am
But don't get hopes too high. My luck with A3's is so far 100%. All must be replaced, that is :D.
My 3rd 3458C waiting ADC board so far, before doing any more testings. Current one does not give errors, but happily drifts +10ppm/day. It does not slow down in any way, after a month of operation already.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: nikonoid on October 26, 2018, 02:46:11 am
SELF TEST PASSED

It was a dead U142 indeed.

(https://uploads.tapatalk-cdn.com/20181026/dc4e0950cd3e21bca3b11cc494f3f4fd.jpg)

Drift test - here we come!
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on October 26, 2018, 04:54:52 am
I wish I'd have your luck :)
GJ!
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: ManateeMafia on October 26, 2018, 10:09:27 am
That is good news.  :-+

I hope your drift tests are passing.
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: nikonoid on October 31, 2018, 02:25:58 am
Just a quick report: 4 days of testing this repaired A3. Total drift 0.52ppm over course of 4 days. I.e the drift is about 0.13ppm per day and it is fairly monotonic (I do ACAL and recheck daily).

Keeping fingers crossed to the end of the week!
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: TiN on October 31, 2018, 04:17:32 am
That's a lot. Unit will be out of spec in a 2 weeks, if drift speed is like that.  :-//
Title: Re: Repair worklog : Old rusty HP 3458A
Post by: martinr33 on November 01, 2018, 02:11:29 am
Well - the out of spec limits is 0.43ppm per day, and the first data here is 0.13ppm per day.

So the unit is in spec - so far -  but it is performing nothing like as well as the better units do.

Interesting that the board has a double fault.

Title: Re: Repair worklog : Old rusty HP 3458A
Post by: seebeck on November 02, 2018, 10:30:14 am
Hi TiN,
I am a volt-nut, I was emailed to you a few times for the "RAM Test 1 High" for my own 3458A.
The final root cause that resulted :-/O in the failure was a battery damaged :-BROKE for a RAM.
Currently, the meter be able to running normally after replacing the broken unit.
Thanks a lot!