Author Topic: Restoration glory of Keithley 2001 DMM  (Read 303922 times)

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Offline ez24

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Re: Restoration glory of Keithley 2001 DMM
« Reply #400 on: September 30, 2015, 04:50:53 am »
Tin
Can I ask what city your are in?  Every time you mention Taiwan it brings up memories of the years I lived in Taipei (Sungsan).
This post is like a history lesson.
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Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #401 on: September 30, 2015, 04:55:40 am »
Taipei it is. :-) But my first piece of Keithley gear, 2001 was bought back when I was in Kiev, Ukraine.
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Offline neslekkim

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Re: Restoration glory of Keithley 2001 DMM
« Reply #402 on: September 30, 2015, 09:00:39 am »
I was asking in the other keithley thread for some time ago, but no answer, so I try to pollute this one instead :)

The two screws to hold the enclosure for the 2015 meter, can anyone verify the threading on those?
It looks like M3, but I'm not sure, and don't want to destroy the threading if it is something else.
I managed to drill out the screws on mine, and want to replace them. (guess I need to use grease or something so they don't rust again)
 

Offline ez24

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Re: Restoration glory of Keithley 2001 DMM
« Reply #403 on: September 30, 2015, 08:01:35 pm »
Taipei it is. :-) But my first piece of Keithley gear, 2001 was bought back when I was in Kiev, Ukraine.
Thanks and even though your work is way over my head, I enjoy reading your posts.
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Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #404 on: September 30, 2015, 08:15:59 pm »
The two screws to hold the enclosure for the 2015 meter, can anyone verify the threading on those?

Bottom screws, or rear plastic bezel screws? I don't have 2015, but I think 2000 using same frame. The only hard thing is to find which screws were there  :scared:
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Offline neslekkim

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Re: Restoration glory of Keithley 2001 DMM
« Reply #405 on: September 30, 2015, 08:22:59 pm »
Bottom, there are only two screws there, countersunk one, very close to m3 in size. But I'm not sure if it is m3, so I don't want to force m3 in there, incase it's some imperial size.

I have tried to read the service manual, hoping that things like that was specified, but couldn't find it

I bought mine from that UK seller that was selling huge amounts of these for some time ago. After trying to open it that time, and the screw was rusted, so I didn't dare to try again.
But I got this lefthand drill bits, and drilled the screw out, and I was suprised of how nice the unit was inside, superclean, no dust at all, no sign at all of caps leaking, or anything, so It seems I was lucky with my unit.

I tried to screw a m3 nut on the screw, but it feels like it's not quite there, so I thought it could be an imperial size, but I'm not so know of those sizes, so I didn't want to force it.
« Last Edit: September 30, 2015, 08:29:28 pm by neslekkim »
 

Offline Macbeth

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Re: Restoration glory of Keithley 2001 DMM
« Reply #406 on: September 30, 2015, 09:29:42 pm »
Take a look at the Keithley 2000 Repair Manual. The 2015 Service Manual doesn't list these mechanical items for some reason. From my brief perusal all the fasteners are imperial. TiN's xdevs will have it, or I think I got mine from tequipment.com. Keithley should have it too but you may have to sign up for it.

ETA: I had heard bad things about the UK seller, particularly his lack of attention to packaging and stuff arriving a bit bashed. I got mine from the Korean seller who has loads going for a fair bit cheaper. No rust at all on mine, and spotless inside. VFD is only really worn on the REAR and GPIB annunciators. This thing has been in a rack all its life. My guess is Samsung.
« Last Edit: September 30, 2015, 09:34:26 pm by Macbeth »
 

Offline neslekkim

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Re: Restoration glory of Keithley 2001 DMM
« Reply #407 on: October 01, 2015, 07:27:22 am »
Aha!, on page 3-5, they are named Grounding Screws
On page 4-10, table 4-4, there are references to screws, but I cannot find any that matches the size, but all sizes given are in imperial units, damn..

I took a picture of the screws I'm inquiring about, attached.
 

Offline Performa01

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Re: Restoration glory of Keithley 2001 DMM
« Reply #408 on: October 01, 2015, 07:56:20 am »
Yeah, this is imperial for sure...
Whenever I have to replace imperial screws, sometimes I get lucky finding a reasonable match in my collection of PC screws. Countersunk ones aren't that common in a PC though. So if I can't find anything, I just cut a M4 thread into the mounting holes and use appropriate metric screws.
 

Offline Macbeth

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Re: Restoration glory of Keithley 2001 DMM
« Reply #409 on: October 01, 2015, 07:57:52 am »
www.boltdepot.com has some really good stuff, in particular the Printable Fastener Tools

As you have them to hand you should be able to measure them up against the printout  :-+
 

Offline neslekkim

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Re: Restoration glory of Keithley 2001 DMM
« Reply #410 on: October 01, 2015, 10:21:32 am »
Wait now, is 4-40 the way to say the with of the screws?, maybe this is the one I need:

4-40X1/4 PHIL FLAT HD UNDERCUT SR WRAP TO CHASSIS

I though 1/4 was the dimentions, but that is maybe the length?, I looked at this chart:
http://www.trfastenings.com/pages/Thread+Conversion+Tables 
And there i find M3, and under UNC and UNF it's written 4-40 and 4-48?

If so I guess screws like this should fit: http://www.ebay.com/itm/131178564711
(need to look for another head though, or attach feets on the unit to not scratch what's under it.)
 

Offline ManateeMafia

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Re: Restoration glory of Keithley 2001 DMM
« Reply #411 on: October 02, 2015, 05:14:44 pm »
@TheSteve

Somehow I have missed your post. I have replaced a switch on a K2001. The original was difficult to actuate and the switch was not that expensive from Tektronix.

I don't like the design. It is open from the rear and does not seem to protect it from contamination. Not good if you are measuring high ohms or volts.

Contact Tek and get a price quote. I think it cost me around $15-20 US. Shipping will probably cost more than that. I had a big order and could justify the cost.
 

Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #412 on: October 17, 2015, 08:53:02 pm »
Hello there, I am having trouble repairing Keithley 2001 #2

All electrolytic caps have leaked out and some corrosion appeared next to U506, U507 and U110.
I have replaced elyts and test diodes in power supply, cleaned the board and tried to switch it back on but with no success.

Self test reported these error codes:
200.1   A/D Zero
200.6   x0.02 Line Cycle Integration
200.7   x0.01 Line Cycle Integration
201.2   7V Reference

ADC board in other, working Keithley 2000 (#1) works well and meter does not report errors.
During 200.x tests the voltage in faulty Keithley 2001  #2 on "AD IN" to "S COM" on ADC board header was approximately 0.8mV.
Thinking that might be the cause I replaced U318 and U319. Offset was then 0.0x mV.
Voltages in tests comparing to Keithley #1 were similar but errors remained.

There is a similar situation described on this website: https://dev.xdevs.com/issues/869 but it did not help me to get to the source of the problem.
Can anyone help?


(Photos attached were taken before repair)
 

Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #413 on: October 18, 2015, 07:10:02 am »
Welcome :)
Are all your voltages OK?

Do you have relays clicking when you power up meter?

Is you reference voltage 7V present (-VREF pin one)? It can be ~10V too, depends on mode.

Do you have any other error, or just those?
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #414 on: October 18, 2015, 10:31:32 am »
Thank you for the answer.

Are all your voltages OK?
Line voltage 240VAC 50Hz

Voltages to "S COM"
+5V    4.9485
+15V   15.028
-15V  -15.050
-8VF  -7.5..7.7V jumping
+8VF   6.8..7.1V jumping
-VREF -10.318
7VM    6.917  (very stable)

Voltages to "COM"
+BS   38.78
-BS  -38.66
HTP   19.46
KTP  -19.52

Do you have relays clicking when you power up meter?
Yes, with little delay after power on. (One relay)

Is you reference voltage 7V present (-VREF pin one)? It can be ~10V too, depends on mode.
Yes

Do you have any other error, or just those?
Just those
« Last Edit: October 18, 2015, 10:39:30 am by SKE »
 

Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #415 on: October 18, 2015, 10:56:20 am »
Alright, sounds like your optical interface working good and ADC is ok, that's good start. Let's do next:

* Select DCV mode, 20VDC range. Enter menu, diagnostics (not self-test!), and have it in 7V div by 1*1 mode. Measure AD_IN, it should be 6.917V. If it's not check U300,U303,U317,U330,U329,U328,Q328,Q525. Check input on buffer and output on buffer (DIP opamp near AD_IN on analog board).

7V div by 1*1.5 should give you 10.5V on AD_IN pin.

Let us know the results. I personally never had just these 200.x errors, only everything together when optical isolation was not working right. Make sure boards are clean and nice.

What happens if you use good ADC board from meter #1 in meter #2? Same errors?
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #416 on: October 18, 2015, 11:19:28 am »
* Select DCV mode, 20VDC range. Enter menu, diagnostics (not self-test!), and have it in 7V div by 1*1 mode. Measure AD_IN, it should be 6.917V. If it's not check U300,U303,U317,U330,U329,U328,Q328,Q525. Check input on buffer and output on buffer (DIP opamp near AD_IN on analog board).
7V div by 1*1.5 should give you 10.5V on AD_IN pin.
I did it before I asked here. No problem found.

What happens if you use good ADC board from meter #1 in meter #2? Same errors?
Yes, same errors.
« Last Edit: October 18, 2015, 11:31:58 am by SKE »
 

Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #417 on: October 18, 2015, 11:36:10 am »
OK, let's go other side.
Did you replaced 1000uF 50V on mains side cap too (if other caps leaked, that one gone boo too, I bet). Replace that cap and clean all around there too.
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #418 on: October 18, 2015, 11:53:50 am »
I replaced all electrolytic caps except C611 (15mF/16V), but it has cca 14mF at 100Hz.
1000uF/16V on CPU board has been leaked out too.
Capacitor check and replace was first think I do.
 

Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #419 on: October 18, 2015, 11:56:08 am »
Ok, so you had checked all those chips and transistors I mentioned? What is actual AC_IN voltages on failed tests ?
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #420 on: October 18, 2015, 12:23:21 pm »
What is actual AC_IN voltages on failed tests ?
I'm not sure what voltage you mean. It's line voltage AC1-AC2?

Bit pattern on the shift registers is same as described in repair manual.
Voltage outputs on U330 looks OK
Voltages on Q328 and Q525 are cca. 0V (in halted test 200.1)
-Vref and 7VM are good, then I think U328 is good too

I try test Q328 and Q525 more detailed.
 

Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #421 on: October 18, 2015, 12:24:55 pm »
AD_IN input on A/D board, during manual steps for 200 series tests.
You can step them one by one manually, and measure AD_IN vs S_COM.
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #422 on: October 18, 2015, 12:37:41 pm »
In all 200.x tests AD_IN to S_COM measured with fluke289 is 0.032mV (In min-max mode fluke catch minimum 0.020mV when test running. maximum is 0.033mV)
Test also failed with connected fluke with same errors.
 

Offline TiNTopic starter

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Re: Restoration glory of Keithley 2001 DMM
« Reply #423 on: October 18, 2015, 12:45:49 pm »
Can you measure U317 pin 15, pin 14 and pin 16 when your meter halted in 201.2 test?
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Offline SKE

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Re: Restoration glory of Keithley 2001 DMM
« Reply #424 on: October 18, 2015, 01:01:20 pm »
U317 after 200.1 test (200.1 on display)
14  -0.020mC
15   6.917V
16   4.9136V

U317 after 200.2 test (200.2 on display)
14  -0.019mV
15   6.917V
16   4.4963V
 


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