On Sun, Mar 4, 2018 at 10:10 PM, Sherry Haibara <v.castelli92@gmail.com> wrote: > Good news, everybody! Thanks to your amazing suggestions, it seems like the > problem is fixed! good to know > 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. the heater filament of the tube has usually a very low resistance when cold. > 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. good job! > 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 yes, usually the wobbling can be cured by replacing some other electrolytics. > 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? DLOAD (and many other commands) exists only on Basic 4.0 If DLOAD"*" gives a syntax error, it's probably Basic 2 You should try to dump the ROM contents and send them to this list, custom ROMs are probably very rare by now. Frank Message was sent through the cbm-hackers mailing listReceived on 2018-03-04 23:02:37
Archive generated by hypermail 2.2.0.