repairing 80's kethley gang switches

[cnt]

I picked up a used kethley 197 for CHEAP and It seems to have a faulty ohms switch, but is otherwise good.  One of the "closed" contacts reads highZ unless wiggled (ohms switch pins 11-12).  It kind of looks like I have to de-solder the whole bank of switches if I want to replace them, which frankly isn't going to happen.

Has anyone fixed these switches in the past?  Any tips/tricks?  I can think of half a dozen hacks to get this working by adding an extra switch to the posts, but I'd rather not do anything hack unless I have to.

I've circled the offending switch in red.

[ataradov]

Start with deoxit or any other contact cleaner. Chances are that's all you need to do.

[David Hess]

I find that squirting contact cleaner in and operating the switch restores proper operation.

The switches come part pretty easy without unsoldering but access needs to be gained.

[ataradov]

Those switches have a hole on the bottom, perfect for contact cleaner spray. And metal frame has corresponding hole, so no disassembly is needed.

[cnt]

Awesome thanks for the tips!  If things go sideways and I do need to disassemble is there documentation or a write up on how to disassemble those switches?

Also I have some "QD Electronic Cleaner" that I use in automotive applications.  I've not used it on anything sensitive before.  Since this has a Gohm input impedance I'm kind of paranoid about leaving residue on the PCB.

[ataradov]

The switch body itself can't be disassembled, but you can find replacements.

Don't use that stuff. Look specifically for "contact cleaner". I guess it is typically a contact cleaner too, but its applications make me think twice. I would at least compare the ingredients with deoxit.

[cnt]

I emailed CRC's "technical service" email asking about their "electronics cleaner" vs their "contact cleaner".  It sounds like either is okay and neither leaves any residue.  Their MSDS seem to both indicate they're just solvents and propellants in the can too. 

I did order the deoxit though since it sounds like deoxit has lubricants in it that are helpful for switches long term.  I'm just going to be careful how I apply it to get it only into the switches.

For posterity sake and in case it helps anyone else here's what CRC said:

Thank you for choosing CRC Products. Our electronics cleaner is our consumer labeled product, and the contact cleaner is the industrial labeled product. The contact cleaner is stronger, but overall they have the same uses and features, fast evaporating, plastic safe, etc. If you are only using it here and there, you would most likely not notice the difference. Let us know if you have further questions.

I then asked if I should go out and buy the "contact cleaner" if I already had the "electronics cleaner" for cleaning switches in test equipment and this is what they said.

I can tell you from experience having used both products that the difference is not enough to go out of your way. I am sure you will be happy with the performance of the electronics cleaner.

 

[David Hess]

I emailed CRC's "technical service" email asking about their "electronics cleaner" vs their "contact cleaner".  It sounds like either is okay and neither leaves any residue.  Their MSDS seem to both indicate they're just solvents and propellants in the can too.

That is exactly the wrong type of switch cleaner to use.  By itself, it will destroy the switches.

These switches use a wiping action so they must be lubricated after cleaning to prevent the contact surfaces from being destroyed.  A combination contact cleaner and lubricant is called for.