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#400 Reply
Posted by
ez24
on 30 Sep, 2015 04:50
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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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#401 Reply
Posted by
TiN
on 30 Sep, 2015 04:55
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Taipei it is. :-) But my first piece of Keithley gear, 2001 was bought back when I was in Kiev, Ukraine.
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#402 Reply
Posted by
neslekkim
on 30 Sep, 2015 09:00
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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)
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#403 Reply
Posted by
ez24
on 30 Sep, 2015 20:01
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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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#404 Reply
Posted by
TiN
on 30 Sep, 2015 20:15
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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
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#405 Reply
Posted by
neslekkim
on 30 Sep, 2015 20:22
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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.
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#406 Reply
Posted by
Macbeth
on 30 Sep, 2015 21:29
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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.
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#407 Reply
Posted by
neslekkim
on 01 Oct, 2015 07:27
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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.
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#408 Reply
Posted by
Performa01
on 01 Oct, 2015 07:56
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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.
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#409 Reply
Posted by
Macbeth
on 01 Oct, 2015 07:57
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#410 Reply
Posted by
neslekkim
on 01 Oct, 2015 10:21
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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.)
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@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.
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#412 Reply
Posted by
SKE
on 17 Oct, 2015 20:53
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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)
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#413 Reply
Posted by
TiN
on 18 Oct, 2015 07:10
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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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#414 Reply
Posted by
SKE
on 18 Oct, 2015 10:31
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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
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#415 Reply
Posted by
TiN
on 18 Oct, 2015 10:56
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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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#416 Reply
Posted by
SKE
on 18 Oct, 2015 11:19
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* 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.
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#417 Reply
Posted by
TiN
on 18 Oct, 2015 11:36
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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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#418 Reply
Posted by
SKE
on 18 Oct, 2015 11:53
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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.
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#419 Reply
Posted by
TiN
on 18 Oct, 2015 11:56
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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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#420 Reply
Posted by
SKE
on 18 Oct, 2015 12:23
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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.
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#421 Reply
Posted by
TiN
on 18 Oct, 2015 12:24
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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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#422 Reply
Posted by
SKE
on 18 Oct, 2015 12:37
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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.
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#423 Reply
Posted by
TiN
on 18 Oct, 2015 12:45
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Can you measure U317 pin 15, pin 14 and pin 16 when your meter halted in 201.2 test?
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#424 Reply
Posted by
SKE
on 18 Oct, 2015 13:01
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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