Electrometer input stage

[don.r]

BTW, don't forget to follow the guidelines in the Keithley 614 manual when replacing front end parts in an electrometer. The parts need to be extra clean before soldering them in. This applies to all electrometers.

Yes, I have lot of experience with repairing their picoammeters like 6485/6487. It was enought to cleang it with IPA after soldering and bake at 50°C for few hours.
One time we sucessfully tried cleaning it with plasma used before high voltage potting componds. But it is strong enough to remove PCB soldermask, which is too much I suppose
Again, thanks all for support and pictures.

LOL! Yes, that might be a bit much. I just mention it because you never know peoples level of experience with things on a forum lke this. Sounds like you are a master at this.

[don.r]

Under the second metal cage there used to be a battery pack for floating operation.

I meant to ask, my battery pack is no longer able to hold a charge would something like this work as a replacement?

http://www.ebay.ca/itm/171198251766?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

It seems to fit the space exactly which is a bonus.