Author Topic: Repair worklog : Old rusty HP 3458A  (Read 172887 times)

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Offline TheSteve

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Re: Repair worklog : Old rusty HP 3458A
« Reply #575 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.
VE7FM
 

Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #576 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.
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Offline kj7e

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Re: Repair worklog : Old rusty HP 3458A
« Reply #577 on: July 19, 2018, 01:49:50 pm »
Is there a boot on the rear as well?
 

Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #578 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.
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Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #579 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 :)



« Last Edit: August 06, 2018, 10:04:32 am by TiN »
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Offline Muxr

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Re: Repair worklog : Old rusty HP 3458A
« Reply #580 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?
 

Online HighVoltage

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Re: Repair worklog : Old rusty HP 3458A
« Reply #581 on: August 07, 2018, 05:06:25 pm »
Looking great, TiN
Do you still have the original VFD's installed in both instruments?
There are 3 kinds of people in this world, those who can count and those who can not.
 

Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #582 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.
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Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #583 on: August 08, 2018, 09:52:03 pm »
Got DIY replacement metal shield for inguard A1 for second meter.



Like a bought one :D



Installed in unit 2:


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Offline nikonoid

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Re: Repair : Old rusty HP 3458A
« Reply #584 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.
 

Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #585 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.
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Offline nikonoid

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Re: Repair worklog : Old rusty HP 3458A
« Reply #586 on: October 26, 2018, 02:46:11 am »
SELF TEST PASSED

It was a dead U142 indeed.



Drift test - here we come!
 

Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #587 on: October 26, 2018, 04:54:52 am »
I wish I'd have your luck :)
GJ!
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Offline ManateeMafia

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Re: Repair worklog : Old rusty HP 3458A
« Reply #588 on: October 26, 2018, 10:09:27 am »
That is good news.  :-+

I hope your drift tests are passing.
 
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Offline nikonoid

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Re: Repair worklog : Old rusty HP 3458A
« Reply #589 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!
 

Offline TiN

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Re: Repair worklog : Old rusty HP 3458A
« Reply #590 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.  :-//
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Offline martinr33

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Re: Repair worklog : Old rusty HP 3458A
« Reply #591 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.

 

Offline seebeck

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Re: Repair worklog : Old rusty HP 3458A
« Reply #592 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!
« Last Edit: November 02, 2018, 10:35:49 am by seebeck »
 
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