My oscilloscope probe started giving weird readings after 2 years

I've been using the same set of passive probes on my Rigol scope since 2022, but last week I noticed the square wave calibration looked all rounded and the voltage readings were off by 15%. Turns out the internal compensation capacitor had drifted and I never checked it because I assumed probes just work forever. Has anyone else had a probe go bad like this after normal use, or am I just unlucky?

3 comments

3 Comments

thomas.river2d ago

Wait wait wait, you didn't check the compensation at all for TWO years? Man that's wild to me. I check mine every few months because I noticed early on that the cheap probes that come with budget scopes just fall apart if you look at them wrong. The internal compensation network thing is real, I've had a probe where the whole waveform looked like a potato after just regular use on a bench. Those little trim caps are basically toy parts soldered in there.

mason_murray82d ago

DUDE, yeah that's totally a thing! I had a probe on my old Tektronix that started rounding off edges after like a year and a half. I just thought my scope was dying until I swapped probes and everything looked clean again. The cheap Chinese passive probes especially seem to drift after a while, the trim caps in them are garbage. You're NOT unlucky, passive probes are consumables basically.

joseph_bailey2d ago

You said "trim caps are garbage" and I gotta push back a little @mason_murray8, it's usually the whole compensation network drifting not just the trim cap itself. The caps are cheap but the resistors in those probes age way worse over time. Still, you're dead right that cheap passive probes burn out faster than you'd expect.