Last week I made a post asking if I should buy an old vintage monitor.
Well, I went back to the recycled goods store this week and it was still there, so $30 later I have it, and it seems to just work*
There's very little about this monitor on the internet, so I'm thinking of documenting as much as I can about it, especially as it's Osborne branded so there could be some interesting history behind it.
* The power button is stuck on, and it does an occasional unsettling arc sound and the image slightly distorts for a millisecond. I believe the latter is fairly common among old CRTs but I don't know much more than that.
Sounds like a degauss!
It's relatively common for CRT screens degauss as they turn on, so it makes some sense that it's still happening, even if the power button otherwise doesn't work - the degauss must be triggered by a different internal mechanism than the one controlling the power
This monitor has no OSD or button to trigger a degauss. The coil will be wired directly to AC via a posistor, so it's entirely passive and will only trigger again when the monitor cools down.
The distortion is caused by the high voltage arcing over, which droops and interrupts beam deflection for a moment. I wouldn't want to run it this way for very long, because it can damage the flyback transformer over time (although the flyback could itself be arcing anyway).
Thanks for the heads up - it'll stay as a very occasional use monitor until I either feel comfortable enough to look inside (after lots of research, given the voltages within) or find a friend experienced in CRTs. I really wouldn't want to blow it up when it could've been prevented easily by maintaining it.
Ragebutt's advice is good RE: maintenance. I would take the back off, make sure it's discharged then clean around the anode cap and in general make sure there is not excessive dust/soot that could form a path for electrical discharge. Clean the anode with alcohol, apply a little dialectric grease to the cup and put everything back together. There is a decent chance that will help, just make sure not to wipe off the black paint on the tube - this is called "aquadag" and it is important to the operation of the monitor.