Gentlemen, As there is so many people on this list who are very familiar with the internals of the VIC-II, I hope someone can help me. I have 250425 C64 board in which the VIC-II does not generate a sync and luma signal, hence no picture at all. It's not the chip itself as it works fine in other boards and I have tried several different VIC-II revisions with the same result. The dot, colour, phi 0 and phi2 clocks all seem good and I have verified that the machine basically runs. I burnt a kernal that does nothing but initialise the VIC registers and then sequentially reads the address space so I can verify all the /CS signals, which all check out fine, including the VIC's /CS. I wondered whether to replace all the caps on the board but the supplies seem free of excessive ripple, the 12v & 5v have about +/- 0.1v but at a very high frequency. I then thought maybe something in the modulator was holding it low so I bent the pin out of the socket but it remains firmly low. What is the minimum requirements a VIC-II needs to generate a sync signal? On other boards I can power it up with no cpu and I get still see a sync pulse, so I'm stumped as to what the problem could be. Any ideas guys? cheers, Rob Message was sent through the cbm-hackers mailing listReceived on 2013-02-03 18:00:03
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