Author Topic: Restoration glory of Keithley 2001 DMM  (Read 205597 times)

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Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #100 on: July 26, 2014, 02:32:00 pm »
I have email notifications on phone, ha-ha.

If you have GPIB connectivity, you can read calibration constants via GPIB.
It can be useful if your digital board fail, as once happened with one of my K2001's (VFD U625 PSU block failed).
I listed procedure and data result on my site - http://dev.xdevs.com/issues/956

I had SRAM on all my STD K2001's too, it's normal to store all data till unit is powered. I never saw unpopulated KI2001 NVRAM socket yet.

Way to unmount APCB is next:

* Remove top black cover on analog PCB (APCB).
* Remove ferrite bead blocks on front and rear input cables, if your unit have them.
* Disconnect front and rear input cables from connector (they quite firm, so you will need to apply some force, but not too much). White cable from front AMPS input is soldered to APCB, so leave that alone for now.
* Disconnect power transformer connectors from APCB and digital PCB.
* Disconnect earth wires from transformer, unscrew one screw holding transformer bracket and carefully remove transformer
* Remove metal clip holding FET and resistor at chassis near mains input.
* Unfix BNC on rear back
* Release push button levers (Front/rear inputs switch to front panel and power switch)
* Disconnect ribbon interface cable from digital PCB
* Now, carefully slide analog board towards front panel.
* Take APCB and lift it starting from front panel side, it should go freely.
* Desolder AMPs input wire from APCB, and you are done.

Be careful with plastic align notches on bottom APCB cover, they are easy to break :) After some practice you will be able to do all this in 2 minutes.
Also avoid touching APCB surface with fingers around VREF area, contamination can easy cause nanoamp sources to fail due to leakage on PCB, and yours ohms on high ranges will fail.
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Offline electronic_eel

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Re: Restoration glory of Keithley 2001 DMM
« Reply #101 on: July 26, 2014, 03:28:54 pm »
Thank you for your detailed unmount description. Will try that once I got the caps.

I planned to dump (and post) the cal eeprom, that should be easy to do with my bus pirate as it is just I2C.
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #102 on: July 26, 2014, 03:30:45 pm »
Keep CPU at reset then, like I described earlier pages in this thread :)
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Offline macboy

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Re: Restoration glory of Keithley 2001 DMM
« Reply #103 on: July 28, 2014, 01:13:37 pm »
P.s. as of MEM2 upgrade, just replacing NVRAM chip is not 100% enough, i had plans to post article about proper procedure, but got other stuff to do and never finished it yet.

Could be a good reason to do so to help you :)
I am very interested in this information. Please tell! ;D
 

Offline electronic_eel

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Re: Restoration glory of Keithley 2001 DMM
« Reply #104 on: August 01, 2014, 03:04:49 pm »
Just got the offer from Keithley about the VFD:

When they got acquired by Tek they changed the part numbers. The VFD changed it's part number from "DD-51C" to "RPT-2001-110". This is a "Display board assembly", it includes the VFD and the board directly attached to it, but not the keyboard and so on.

They offered me the part for 375 EUR, with VAT that is 450 EUR. Wow, that is just a bit less than I payed for the whole 2001.   :wtf:

Will now reconsider changing the VFD, maybe I buy a cheap used 2700 scanner and transplant the VFD from there.

Or does somebody have a matching VFD lying around as spare and wants to sell it?
 

Online jpb

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Re: Restoration glory of Keithley 2001 DMM
« Reply #105 on: August 01, 2014, 03:29:29 pm »
Just got the offer from Keithley about the VFD:

When they got acquired by Tek they changed the part numbers. The VFD changed it's part number from "DD-51C" to "RPT-2001-110". This is a "Display board assembly", it includes the VFD and the board directly attached to it, but not the keyboard and so on.

They offered me the part for 375 EUR, with VAT that is 450 EUR. Wow, that is just a bit less than I payed for the whole 2001.   :wtf:

Will now reconsider changing the VFD, maybe I buy a cheap used 2700 scanner and transplant the VFD from there.

Or does somebody have a matching VFD lying around as spare and wants to sell it?
I just bought (7th July) and replaced the VFD on a Keithley 2015, they wouldn't sell me a board (couldn't find a part number) but just the VFD (DD-52) was £53 + VAT. This is a simpler VFD than the one on the Keithley 2001 but I would think that if you can persuade Keithley to sell you a DD-51C it would be more like a 100 Euro (just a guess).

A word of warning, as I was trying to remove the old VFD in tact I managed to damage one of the tracks on the board when desoldering. Fortunately I could do a bodged solder fix, but if I was to do it again I'd sacrifice the old VFD and cut the pins and then desolder them separately.

EDIT : another word of warning, on the Keithley 2015 the VFD is held to the board by thin double sided sticky tape (a bit like electrical tape but with glue on both sides). Part of the reason I damaged the track was I was prizing the display away from the board and it wasn't quite desoldered. It would certainly be easier to just replace the board but I didn't have that option.

Keithley seem to charge widely different prices. I thought £53 for the VFD reasonable, but I also bought a tiny plastic bit that holds the board in place (mine had broken when I received it) and just one of these cost £9 + VAT!
« Last Edit: August 01, 2014, 03:35:27 pm by jpb »
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #106 on: August 01, 2014, 03:39:32 pm »
Ouch, 450 is a lot. You can get another dead 2001 on bay for that, just like I did 2 years ago, ending up with 7 DMMs  :-DD

And beware, 27xx, 2000, 2010, 2015 series DMMs are using simpler segment VFD, while 2001,2002,700x,24xx,26xx use dot-matrix dual-line VFDs.
There are some 7001's on sale now with working VFD in 100-150usd range, plus few "for parts" for less, but could not power on/no proof that VFD ain't cracked.

I got 2400 SMU before with broken VFD, shown few photos on related thread: https://www.eevblog.com/forum/testgear/keithley-2400-sourcemeter-review-and-teardown
There was caveat, pins formed in checker field on 2400 front panel PCB, while on mine 2001's and 7001 VFD is just single pin row. So had to do some bodging.

For sure, cut pins on broken display with sharp knife first, the remove remnants and solder from holes with copper wick.
As of removal good display - use solder wick to remove solder and free pin in it's hole. It will take some time, but this way you not risking of killing VFD contact bond to glass (which likely to happen if you try use heatgun to reflow PCB and apply force to release VFD from it).

P.S. I don't have spare VFD, sorry.
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Offline electronic_eel

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Re: Restoration glory of Keithley 2001 DMM
« Reply #107 on: August 01, 2014, 03:44:17 pm »
I just bought (7th July) and replaced the VFD on a Keithley 2015, they wouldn't sell me a board (couldn't find a part number) but just the VFD (DD-52) was £53 + VAT.
This price is similar to what Agilent is offering for a replacement of the 34401A VFDs.

This is a simpler VFD than the one on the Keithley 2001 but I would think that if you can persuade Keithley to sell you a DD-51C it would be more like a 100 Euro (just a guess).
I tried that but they said it isn't available anymore. Don't know if that is true, but I sent them an extra email reply asking for it.

 

Offline electronic_eel

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Re: Restoration glory of Keithley 2001 DMM
« Reply #108 on: August 01, 2014, 03:49:52 pm »
And beware, 27xx, 2000, 2010, 2015 series DMMs are using simpler segment VFD, while 2001,2002,700x,24xx,26xx use dot-matrix dual-line VFDs.
Sorry, mixed that up. I meant 700x.

For sure, cut pins on broken display with sharp knife first, the remove remnants and solder from holes with copper wick. As of removal good display - use solder wick to remove solder and free pin in it's hole. It will take some time, but this way you not risking of killing VFD contact bond to glass (which likely to happen if you try use heatgun to reflow PCB and apply force to release VFD from it).
Thanks for the tips. But I got a true THT rework station from JBC. The special desolder tip can heat while the pump sucks the molten solder at the same time. So no more desolder wick or cut pins needed. Didn't have any desoldering problems anymore since I got that station.
 

Offline electronic_eel

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Re: Restoration glory of Keithley 2001 DMM
« Reply #109 on: August 13, 2014, 07:25:25 pm »
I bought one of the broken 7001 switch units on ebay and asked the seller to send me just the front panel to save shipping costs. Today I collected it from the customs office. Before I start soldering on my unit, I just hooked up the 7001 front panel to my 2001:

Meet the Frankenmeter   ;D

The defect in the 7001 must've been somewhere else (I guess leaked caps, mfg date of the ICs on the front panel was '92) - the vfd is working fine. It certainly isn't brand new, but readability is good and a big improvement from the vfd I have on my 2001.

As you can see the display portion is fully compatible between the 2001 and 7001. But the keys are completely different, so you can't navigate in the menu and so on.
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #110 on: August 13, 2014, 11:09:27 pm »
If you look carefully, original 2001 front panel PCB, microcontoller on it is programmed to 7001-800-A01 firmware.
And front panel MCU talks to main CPU via simple UART protocol. And that's same with 2002,24xx,26xx units which share same display ;)

I have idea for long time already to have one of meters converted to mini-ITX PC, as motherboard fits nice inside instead of analog board. Would be neat little computer
to install in rack together with measurement gear, for datalogging/internet control for example :) Maybe I'll make that happen one day.
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #111 on: September 09, 2014, 09:19:23 pm »
Hi, I am having trouble repairing Keithley 2001
Self test reported these error codes:

201.3   Test Cal Zero
300.2   1.75V Reference, x5 Gain
304.7   4.4nA and 770nA Ohms Sources
310.1   Amps Protection
412.1   AC Amps Switch

Sometimes it will blink „owerflow“ between readings and every other range will measure approximately 1/2 of estimated value.

Could somebody share the complete schematic for this analog board?
Thank you in advance for your help
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #112 on: September 10, 2014, 11:31:41 am »
Anyone opened meter before?
Check input circuits, 310.1 suggests there might be some issue.

Check voltage on ADC Input when running diagnostics item 2V div by 1 * 5.
Also check REFIN voltage. Should be around 7VDC stable, it's output from LM399 reference.

There is no complete schematic for 2001 in public, not that I aware about of any.
But you are welcome to join efforts of reversing one if you want.
Even little help like taking detailed photos of your boards helpful ;)

Latest schematic pieces are posted here
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #113 on: September 11, 2014, 09:52:35 pm »
I don't now if anyone opened the meter. It is possible, but boards looks untouched.

Circuit 310.1:
CR309 and Q314 seems to be OK
CR305 has internaly disconnected diode between pin 3(AC) and 4(-)
I measured 14ohm resistance between pins 2(AC) and 3(AC) on board (CR305 unmounted)
It that OK?
It's  hard to track signal lines.

ADC Input voltage, when running diagnostics item "2V div by 1 * 5", is cca +3.180V.
Also some voltage is on pins 2, 3 6, 7 of U318.

REFIN- on ADC board is -10.330V
LM399 seems to be OK

I replaced CR305 with KBU8, these errors remained:

201.3   1.75V Reference
300.2   1.75V Reference, x5 Gain
304.7   4.4nA and 770nA Ohms Sources
« Last Edit: September 12, 2014, 12:11:34 am by SKE »
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #114 on: September 12, 2014, 04:43:41 am »
Quote
REFIN- on ADC board is -10.330V

I'm afraid that's not OK. It should be +7.xxx VDC.
Check U330, U328, U317, U322, U304

Quote
304.7   4.4nA and 770nA Ohms Sources

This is common error if there is any leakage on PCB near U322,U325,U333.
If board is really clean - check U333, Q317, U323, U325,U332.

If u had broken CR305, it's protection for AMPs input, check also Q310,Q305,Q309,Q307 (big transistors near CADDOCK network).

I can help you with reference measurements later, if you post photos of suspected areas with your results :)

--------

Meanwhile I got some addition to my broken Keithley's collection :D

It's borked Model 2000 this time. Why I bid on it? Well, I thought somebody else will win, haha.
Quote
This units powers up but not working it is mainly for part or repair, what you see in the pictures is exactly what you going to receive

It's pretty banged up, but display still intact, and units powers on, according to seller's photos.
So will be interesting to play with lesser brother to 200x's. Also chinese guys reversed schematics for it before, so that's another reason why repair should be easier.

Will post endeavors about it when I receive it.
« Last Edit: September 12, 2014, 04:48:47 am by TiN »
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Offline ElektroQuark

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Re: Restoration glory of Keithley 2001 DMM
« Reply #115 on: September 12, 2014, 06:37:26 am »
Quote from: TiN on Today at 03:43:41 PM
Also chinese guys reversed schematics for it before, so that's another reason why repair should be easier.


Any link to it?

Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #116 on: September 12, 2014, 02:03:08 pm »
I checked reference circuit again
Voltage on U328 between pins 2 and 6 is 6.9..V and it's stable
Voltage between pins 2 and 3 (U328) is stable zero.
I think it's OK.
Voltage between pins 7 and 13 on U330 is 6.9..V
I don't sure for purpose U330B.

Voltage between -VREF and SCOM on ADC board is -10.330V (-VREF is negative)

Q310,Q305,Q309,Q307 seems to be OK

EdoNork: I don't found any schematic from chinese :(
 

Offline ElektroQuark

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Re: Restoration glory of Keithley 2001 DMM
« Reply #117 on: September 12, 2014, 02:14:03 pm »
Quote from: EdoNork on Yesterday at 05:37:26 PM>Quote from: TiN on Today at 03:43:41 PM
Also chinese guys reversed schematics for it before, so that's another reason why repair should be easier.


Any link to it?


Just found it. It's HERE.

 Thank you.
« Last Edit: September 12, 2014, 02:16:40 pm by EdoNork »
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #118 on: September 12, 2014, 02:52:03 pm »
Yea, i rehosted it on my site, but it's downed right now due to server internet issues.
Original author of 2000  schematics is from bbs.38hot.net forums.

SKE

U330 is precision multiplier/divider for reference voltages, using flying capacitors. Check LTC1043 datasheet for more details.
I'll do measurements tomorrow, i have exact same revision boards u have.

Also worth to check VF- VF+ voltages, should be around 38V. And if I would be you - i'd replace all electrolytic caps on analog board, your meter is old, and those caps are dying. You can see what could be a result few pages before in this thread...
« Last Edit: September 12, 2014, 02:58:56 pm by TiN »
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #119 on: September 12, 2014, 04:05:17 pm »
Capacitor check was first think I do.
I was found small amount of electrolyte under the capacitors.
Even though orginal capacitors has good capacitance and ESR (measured at 100Hz and 1Khz)
I decided to replace capacitors with Panasonic EEUFR series.
Floating voltages seems to be OK.

In the pictures of analog board are new panasonic capacitors.
 

Offline Jaap

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Re: Restoration glory of Keithley 2001 DMM
« Reply #120 on: September 22, 2014, 11:01:24 pm »
Hello All, I'm new to this list and this is my first activity on this forum.

Since one week I have a 2001.  I got it for free. At first it did not start up OK every time. Since then I took it completely apart. Changed the power supply caps (tip from this forum). Was necessary too - found some cap fluid. Cleaned some contacts and did some re-soldering on previous repairs and since then it starts up perfectly all the time. Build in test are all OK.

Now my question. I would like to upgrade to MEM 2 because of more setting storage. As I have read I need a DS1245Y for that. But is that all to it? Probably not.


TiN said before:
P.s. as of MEM2 upgrade, just replacing NVRAM chip is not 100% enough, i had plans to post article about proper procedure, but got other stuff to do and never finished it yet.

Could be a good reason to do so to help you :)



TiN, could you help me a bit more on this?

Thanks in advance.
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #121 on: September 24, 2014, 12:52:55 am »
Okay, let me finish guide today.
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Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #122 on: September 24, 2014, 04:24:37 am »
Done :)

Article of memory option installation on Keithley 2001/2002

I don't have DS1244 or DS1248 yet, will update it after for K2002.

Hope this helps, let me know if any questions.
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Offline Jaap

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Re: Restoration glory of Keithley 2001 DMM
« Reply #123 on: September 24, 2014, 03:27:44 pm »
Hello Illya

Thanks for the quick response and your work. I will start on this soon and will let you know my progress.

Jaap
 

Offline TiN

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Re: Restoration glory of Keithley 2001 DMM
« Reply #124 on: September 24, 2014, 04:13:18 pm »
Hope it helps.

Should be no problems to get it working. I had only issue finding programming tool which can write those few bytes into DS1245/44/45/48Y

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