Den Tue, 3 Oct 2017 15:05:26 -0600 skrev Terry Raymond <firstname.lastname@example.org>: > Well, > My fiddling with my flat NTSC C128 this summer I found > The power regulator (located to right of MMU chip) > On the output voltage- nothing, but reading OHMS resistance using a > digital Multimeter that has the OHMS Buzzer reading: > Power Regulator to GND reading the output voltage should have about > 12VDC nothing Does the regulator get hot? > Reading just resistance on regulator with buzzer, the buzzer barely > tries to beep indicating a dead short. A very strange buzzer if it barely tries to beep to a dead short. All buzzers I've ever seen or heard of beeps as much as they can on a dead short. > The SID and VIC Video uses the 12VDC! > So both SID and VIC circuits have shorted components. Why do you assume it's on both circuits? You could try to ohm measure at some different points in the 12V supply, preferable on each capacitor, to se where you get the lowest reading. This is a bit hard as the wires to the multimeter and the measurement pins themself usually have a rather high resistance in comparision to a short circuit. Preferable you should use an ohm meter with "4-wire measurement" but that's something few people have among their measuring equipment at home. If you remove the SID and VIC chips, which usually are socketed, then there is mostly some capacistors on the 12V supply. Desolder one electrolytic capacitor at a time until you get the 12V supply to work. (I assume that it's safe to turn on the power on a C128 without SID and VIC chips, it might even display text on the 80 column output). Maybe the RF modulator also uses 12V DC? If so you should check if there is some electrolytic capacitors in the rf modulator that could short the 12V supply. > I think a cranky power source may have caused the issue. Unlikely. If the 12V regulator is of the 7812 kind, it can withstand 35V more the input than the output, so the regulator itself should be able to handle 47V DC (or atleast 35V DC) on it's input. For that to happen you need to feed 35 (or atleast 26V) AC on the 9V AC input. That would happen if you feed a bit over 300V AC to the 110V AC input on the transformer, if it werent for that the transformer would get saturated before you reach that voltage. So no, it seems virtually impossible to destroy anything on the 9V AC AC / 12V DC part of a C64/C128 by feeding something incorrect on the power input, as long as you don't just grab any random irrelevant equipment and connect to the power input socket. Highly unlikely on a C128 as the only other stuff that fits the socket is an Amiga power supply and a C128 should be able to withstand such supply. > I trying to find enough components from a parted out 128, for parts. > > Fun project for the winter months. > > Terry Raymond > -- (\_/) Copy the bunny to your mails to help (O.o) him achieve world domination. (> <) Come join the dark side. /_|_\ We have cookies. Message was sent through the cbm-hackers mailing listReceived on 2017-10-04 00:00:03
Archive generated by hypermail 2.2.0.