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The various range switches on my oscilloscope obviously collected some dirt over the years. Sometimes the input attenuators show a frequency dependent response (just like poorly matched probe) and the timebase wiggles all over place. It is a fully analog scope and I have full service manuals.

I've seen spray cans used for cleaning these switches, are they any good for this kind of job (measurement equipment)? Are there particular types I should avoid? Are there particular techniques / best practices to clean these switches?

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  • \$\begingroup\$ What kind of scope? Have a photo of the switches from the inside? Old Tektronix used silver since silver oxide is a conductor. Relay and tuner cleaners that leave no residue should be OK \$\endgroup\$ – C. Towne Springer Feb 14 '14 at 23:13
  • \$\begingroup\$ @C.TowneSpringer Philips PM3209 I've been trying to find a PDF version of the datasheet online, but didn't find any. In the paper version there are no images either. It is a Philips budget scope, 40MHz dual time base. \$\endgroup\$ – jippie Feb 14 '14 at 23:14
  • \$\begingroup\$ The lazy man's solution is to just move the switches through their range a couple dozen times. Sometimes, this alone gets them "clean enough", without any need to open the case. \$\endgroup\$ – Phil Frost Feb 14 '14 at 23:17
  • \$\begingroup\$ @PhilFrost yes that works for short period, but it is getting annoying lately. It is a perfectly good scope otherwise. \$\endgroup\$ – jippie Feb 14 '14 at 23:19
  • \$\begingroup\$ I believe from memory the switches are open multi-layer rotary switches. Not sure what the proper name is. \$\endgroup\$ – jippie Feb 14 '14 at 23:20
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Contact cleaner should work fine. Dave Jones on the EEVblog used it to clean the switches on an analog oscilloscope he got in an auction and it worked perfectly.

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  • \$\begingroup\$ Won't dust / dirt build up more easily afterwards, because I guess that is what I'm most worried about at the moment. \$\endgroup\$ – jippie Feb 15 '14 at 7:03
  • \$\begingroup\$ No more so than it did before. You aren't actually breaking any hermetic seals to apply the cleaner. \$\endgroup\$ – Ignacio Vazquez-Abrams Feb 15 '14 at 7:41
  • \$\begingroup\$ If there were any hermetic seals I probably wouldn't have the issue in the first place ;o) \$\endgroup\$ – jippie Feb 15 '14 at 7:42

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