Dropped $800 on a used oscilloscope from a guy on Kijiji

It arrived with a dead channel and a crooked knob but I fixed it with a $2 trimmer cap and some contact cleaner, has anyone else found hidden fixes on older test gear?

2 comments

2 Comments

fiona7371mo ago

Grace actually has a good point about the crooked knob being a mechanical issue, not an electrical one. But I have to disagree that replacing a trimmer cap is something most people would think of before swapping the whole board. A lot of vintage scope issues come from drifted ceramic or silver mica caps in the vertical amp section, and a $2 trimmer can save hours of troubleshooting. @grace_hunt84, next time you see a dead channel on an old Tek or HP scope, check those little trimmer caps near the input jacks first before pulling out the soldering iron.

grace_hunt841mo ago

Hang on, you GOTTA tell me more about that trimmer cap fix because that's actually NOT a hidden fix most people would think of. Usually with dead channels on old scopes folks just toss them or try to recap the whole board. You hit the nail on the head with contact cleaner though, that stuff is magic for dirty switches and pots which cause like 80 percent of the problems on vintage gear. One thing though, a crooked knob is almost always just a loose set screw or a bent shaft on the pot itself, not a cap issue. Make sure you check the shaft alignment before you start poking around with a soldering iron next time or you might bend a trace.