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 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 11:00:02
Archive generated by hypermail 2.3.0.