Good news, everybody! Thanks to your amazing suggestions, it seems like the problem is fixed! I'm not entirely sure about what was wrong in the first place, though: as I later determined, what I was measuring without the voltage regulator in place was not in fact a short, but the resistance of the tube - or something closely related to that. With the tube disconnected, the resistance between the output of the regulator and ground was indeed in the order of megohms. The diodes of the rectifier were fine, as were all the traces and the L701 coil. I just ended up replacing the voltage regulator and applying fresh solder on all the solder joints of the power supply circuit, like those of the diodes in the bridge rectifier and of the big 4700 uF capacitor, and amazingly enough, it works perfectly now. My best guess so far is that either the voltage regulator itself died after the first power-up due to old age, or that a combination of electrical, thermal and transportation stress may have weakened some of the solder joints. There is just an extremely minor vertical wobbling of the image which is very hard to notice, and which may suggest that the caps are in need for a replacement, but for now I'll probably leave them alone. The screen is crystal clear and pretty much on focus. The logic seems to be in working order - to be fair, I did not perform an extensive test, limiting myself to printing a "hello world" message, but so far so good. It seems like it's running some sort of custom ROM, because the greeting message is "*** PET Club Scharinger ***", which seems to be referring to an Italian IT company founded in 1979 in Sudtirol, instead of the usual "*** COMMODORE BASIC ***". Is there an alternative easy way to determine which BASIC version it's running? -- Sent from: http://cbm-hackers.2304266.n4.nabble.com/ Message was sent through the cbm-hackers mailing listReceived on 2018-03-04 23:00:04
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