Re: C64 to C64C mobo conversion

On 6/24/22 10:46, tokafondo_at_tokafondo.name wrote:
> 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.

You have a 250409 board? I'd like to see a picture of that one. After 
the 250407 the 250425 was the next one.


> 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.

Yes, you can replace a 6510 with a 8500 and the other way round without 
problems.

  Gerrit