On 26/10/2016 4:38 AM, Hegedűs István wrote: > Hi, > > It has black screen of course. I know that the Kernal ROM or VIC used > to be the guilty ones. I have burnt a 27c128 with Kernal but still > have to build an adapter so I cannot 100% rule out Kernal issue. The > guy who sold it said that the 6502 is also sick (he has tried the CPU > in an 1541), though with oscilloscope I have seen e.g. proper phi2 > signal coming out. I have bought some Rockwell 6502s to replace it. > Anyway even if it turns out that VIC is good it is better to have a > spare IC. > I should hook up my logic analyzer to it but so far I had no time (or > I was just too lazy). > Whilst mask ROM (and RAM for that matter) failures are common on vintage equipment, the last two VIC-20's with a black screen that I repaired had a bad 6561-101. In my case both were easy to diagnose by simply plugging in a cartridge or blind loading a game. On both occasions the game you could hear the game playing even though there was a black screen. Message was sent through the cbm-hackers mailing listReceived on 2016-10-26 02:00:02
Archive generated by hypermail 2.2.0.