Dropped $1200 on a used oscilloscope off eBay, got burned bad

Found what looked like a decent deal on a Tektronix TDS 210. Seller said it worked fine, just some cosmetic wear. Got it in the mail and it won't hold a calibration for more than 20 minutes. Traces drift all over the place. Been troubleshooting it for a week now and I think the power supply board is toast. Has anyone had luck fixing these old scopes or am I better off just eating the loss?

2 comments

2 Comments

the_olivia1mo ago

Used to think eBay buys were all about getting lucky with old gear from people who just didn't want it anymore... but honestly stuff like this changed my mind pretty quick. Bought a similar Tektronix thinking I was getting a steal and ended up spending more on replacement caps and time than if I'd just bought a newer Rigol. Those old power boards are notorious for failing, especially if it's been sitting in a damp garage or something.

emmafisher1mo ago

Oh man, that sucks... I've been there with a very similar Tektronix scope. If the traces are drifting that bad after 20 minutes, check the main filter caps on the power supply first. They dry out over time and cause all kinds of weird voltage ripple issues. I'd open it up and look for any bulging or leaking caps near the transformer, then measure the voltages on the output rails. Sometimes you can get a cap kit for like 30 bucks and fix it yourself if you're handy with a soldering iron.