24 de junio de 2022 9:46, tokafondo_at_tokafondo.name escribió: > 24 de junio de 2022 5:46, "Gerrit Heitsch" <gerrit_at_laosinh.s.bawue.de> escribió: > >> On 6/24/22 03:26, tokafondo_at_tokafondo.name wrote: >> >>> I have a pre-8701 C64 motherboard and a C64C motherboard. >>> If I wanted to test 8580 and 8563 chips in the C64 motherboard, would it > be just enough with >>> replace the 7812 with a 7809? >> >> No, the VIC from a C64C expects 5V on Pin 13. You can get that from Pin 40, but it's a good idea to >> run it through a ferrite bead and put a 100nF capacitor between Pin 13 and GND. >> >> Also, you might have to rework the modulator since the 856x VIC expects a 1kOhm pullup while the >> 656x VIC wants a 500 Ohm pullup on the luma signal. This pullup is found inside the modulator. Just >> replacing the VIC might result in a dark video signal. >> >> Gerrit I want to thank you again for your advice. I created a small adapter by using a 40 pin female socket and put the 8565 in the C64 board and now it works, so the culprit here was the 6569R3 ceramic chip. Now I want to test the 6581 in the C64C board, as the 8580 makes no sound at all, and I found the 6581 to actually work. Thanks, again. > > Thank you very much. I have both a 250407/251137 REV.C and a 250409/252311 REV.A motherboards. The > former powers up but I have no sound except for the click in the audio when turning it on. The > latter just show a white screen on the screen, and there is a light voltage drop in the +5v line > that feeds the top row of chips. > > So I want to test some 85xx parts in the 65xx board. I will start with the 8500 in the 6510 socket, > as they say it's a direct replacement.Received on 2022-06-24 13:00:07
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