Uncreative Labs

Joined: 10 May 2008 Posts: 62

I just recently acquired some old computers which included four commodore computers. I've got a VIC-20, Plus/4, 2 C64s, and 1 C64c.

One of the C64s was dead. It would power on but get no video. I removed the SID chip with an IC extractor and the system powered on and video displayed on the machine. Everything (else) worked. I have an older brownbox C64 that has damaged casing. It had a good sound chip. So I remove the SID with the IC extractor and place it in the slot of the C64c. The chip is definitely inserted correctly and all contacts look good. However, sound is not working on the C64c that I installed it on. Everytime I load a game no sound is output. The PSU brick is good because I used it on the other C64 and didn't have sound problems. (I have seen on another forum where someone's C64 sound was acting up due to a faulty PSU)

The C64c just for some reason doesn't want to communicate with the sid chip properly. Any ideas on how to correct this?

Thanks in advance.

Joined: 23 Jan 2011 Posts: 4 Location: NRW, Germany

I suppose 1 of the C64s is a breadbox? While the other one is an "Amiga styled" C64C?

In that case it won't work because both have different SID Chips (6581 used on earlier models and the 8580 used on the later models). The 6581 needs 12V for operation, while the 8580 works with 9V ... otherwise they're pin- , but not exactly function-compatible (different sets of internal filters). If you manage to supply the SID in your C64C with 12 volts, it should work, but don't rely on this ... SID chips can be killed quite easily.

Also NEVER put a 8580 in a Breadbox, that way you WILL kill the chip when powering on.

Joined: 10 May 2008 Posts: 62

What I find unusual about the slimline C64c is that the motherboard is dated 1983. It also had a 6581 in the SID socket. The brownbox C64 motherboard is dated 1984. It had a 6581R3 in the SID socket.

Joined: 23 Jan 2011 Posts: 4 Location: NRW, Germany

dw wrote:

What I find unusual about the slimline C64c is that the motherboard is dated 1983. It also had a 6581 in the SID socket. The brownbox C64 motherboard is dated 1984. It had a 6581R3 in the SID socket.

That's odd ... that way the chips should be interchangeable. Either someone replaced the mainboard in the C64C already ... or you have one of these rare breadbox -> slimline conversion kits which used to be popular in australia (looks like this http://www.richardlagendijk.nl/foto/cip/computer_c64_australian_01.jpg)

Joined: 10 May 2008 Posts: 62

shock__ wrote:

dw wrote:

What I find unusual about the slimline C64c is that the motherboard is dated 1983. It also had a 6581 in the SID socket. The brownbox C64 motherboard is dated 1984. It had a 6581R3 in the SID socket.

That's odd ... that way the chips should be interchangeable. Either someone replaced the mainboard in the C64C already ... or you have one of these rare breadbox -> slimline conversion kits which used to be popular in australia (looks like this http://www.richardlagendijk.nl/foto/cip/computer_c64_australian_01.jpg)

Wow.. thats fascinating. But my 64c looks like the normal streamlined version that was released. I think what might have happened is the person I bought all this equipment from had monkeyed around with the SID chips.