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Old 12-29-2017, 11:02 PM
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MadMan MadMan is offline
'A Disgusting Brony'
Join Date: Oct 2016
Location: Chicago
Posts: 727
B&K 1460 O-scope troubles

This is my go-to scope for all my actual work-related needs. It's a good runner but I'm afraid it's starting to have troubles. While monitoring a serial data stream on a Cadillac with communication issues, everything was fine, and the data 'on's or '1's were about 1 grid unit high. I left it on for about 10 or 15 minutes (the car and the scope) and when I came back, it was about 1/2 a grid unit high.

I'd never seen this on data before, but I have seen this several times on crank sensor signals - in fact, I've watched analog crank sensors lose their height (voltage) on the scope slowly until the car shuts off from lack of input. Nice way to confirm a bad crank sensor. So for a while I was fairly certain the scope was doing its job.

What I did this time was, I left the car on so the data kept on streaming, and turned the scope off for 15 minutes, then turned it on and sure enough, 1 grid unit high.

I'm eyeing the electrolytics. They're made by 'Elna' but none are visibly swollen or anything. There's also a very large square metal high voltage can capacitor near the power supply, made by Nichicon. I can't find a manufacture date but I'd venture it's in the 70s somewhere.

TLDR: My scope is partially losing it's vertical... amplification or deflection or something like that, when it warms up. What do?
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