| Electronics > Repair |
| Keithley 2002 repair help |
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| nikonoid:
Thank you. I will give it a try. Sent from my iPhone using Tapatalk |
| ManateeMafia:
How about some soldering tip tinner? That may help remove any oxide on the via. |
| TiN:
Why even bother with transformer wire? Just get piece of regular multi-strand UTP cable (LAN RJ45 cable) and take a strand from there. It will be bare copper metal, which solders like a champ. When I was fixing my first 2001, I just heated via from the bottom side with the iron set to +240c, and poked a copper strand from top side till it goes thru and sticks from the bottom. Then you just cut the top remaining wire and solder it down on top as well. Takes just a minute once you practice a bit. if via on either side peels off, you just use same strand to extend to the PCB trace track and connect there. Don't use solder only bridges, as solder != copper tempco (%0.4/C!) which might be important for analog traces! |
| martinr33:
Another good alternative is wire wrap wire - solid core, 30 AWG, silver plated, Kynar insulated. If your solder is not taking well, you probably have contamination on the exposed traces. The capacitor electrolyte has combined with the copper to create a compound that is hard to solder. Your solder bridge is probably making contact in tiny areas, which is no good. I would clean the solder off, and look to see how much of the underlying trace is tinned. This is a precision instrument and the board is sensitive to contamination from cleaning products. Or finger oils. Or just being in open air. So whatever you use to clean it, pick something that is easy to wash off. I'd start with white vinegar, being very careful not to get it on the rest of the board - use a damp rag. On really bad corrosion, I use MG Chemicals tin plating solution. As well as dissolving junk, it plates a thin layer of tin onto the copper - but you have to clean it off carefully. The plated tin makes the trace easier to solder. On your question about standards and the 732a - 8.5 digit meters are quite noisy in the last digit or two. A 732a gives you a stable, quiet voltage so you can see how much noise your meter has. My K2002 has an SD of anywhere from 300nV to 1.2uV on the 10V range with shorted inputs, depending on NPLC and filter settings, and other variables like time of day. My Advantest units do 200nV - 700nV.I'm bringing up a 732a now - it is nice to see similar noise from the 732a 10V output as I do on a shorted input. And the two Advantest units I have hooked to it will differ by anywhere from 1 - 5uV. Now, I am using rubbish cables but the temperatures should all be stable by now. Good luck with sorting out that board - it's worth the effort, the K2002 is a good meter. You also have one of the first run of units there. Post if you need help with the EPROMS. |
| macboy:
--- Quote from: martinr33 on August 10, 2017, 03:45:27 am ---Another good alternative is wire wrap wire - solid core, 30 AWG, silver plated, Kynar insulated. --- End quote --- +1 on this. It should be the first choice, not an alternative. The strand of cat5e cable would be an alternative to this. You can straighten it after untwisting by grabbing a length of it and pulling it until it just gives a little. The copper will then be perfectly straight. |
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