Yes, another high risk Ebay purchase from the UK. The Commodore 64C, my first one ever. It is beautiful, isn’t it? I didn’t like the design much it when I was a kid – it didn’t “feel” like a real Commodore 64 then. But now, I think that it is one of the best home computer designs ever. Darn that thing is sleek!
Besides being hot as hell design-wise, it was also in surprisingly good shape. The keys has yellowed over the years, of course, but that can be fixed with a bit of chemicals. Maybe I’ll do it this spring (you’d need sunlight for that treatment). The functionality seemed okay at first. The keyboard was working 100 percent. Disc drive and tape worked fine. First game test checked out. But when I started testing more games, peculiar things would happen. Some games, like Dig Dug, Boulder Dash II, Space Action, Toy Bizarre worked fine. Others, like Jumpman, Pacman and most of the others behaved strangely. What the Hey! Let’s open her up and see if there is some visible goo going on in there.
No, luckily, the inside looked totally fine. No leaking capacitors. No loose solder joints at first glance. Not too much dust. But hold on! Is that a NTSC setting at J3? Open=NTSC. I don’t want a NTSC machine. Hold on again! The VIC-II chip is 8565 (PAL). The crystal frequency is unreadable, but ends in ..75 The correct frequency should be 17.734475MHz, as every preschool kid knows. So it is the right crystal. Did some previous owner just forget (or lacked the knowledge) to shorten J3 in a NTSC-to-PAL conversion attempt? Confusing.
Actually, I suspected as much. Underneath there is a “Radio Shack” sticker covering one of the screw holes, and it has been opened since. Even though Radio Shack, now bankrupt, expanded into Europe, I think this computer was originally sold in the US. A piece of history here! But NTSC? No, no, no. It has to be corrected soon. Though it could actually explain the weirdness in the games test.
But, with some further reading here, and looking at the pictures from that post, example below:The J3 shortening is done by just solder on top of one of the joints. No need to go between apparently. My C64C is therefore PAL by default manufacturing. Sold in the UK.
So, back to the drawing board. What could be wrong. Something with the IC’s or control ports maybe? The SID chip could be fried. SID’s cost at least 20 euros, if there even is one for sale, so I hope that’s not the case. I searched for some test programs, but couldn’t find anything written. On Ray Carlsen’s page I found some type-ins and tried them out, but not until I enhanced the joystick test program of course. It needed more clarity. And what do you know – control port 2 needs some lovin’. It returns the code for “fire” all the time – 111 – when it should read 127 for a healthy port.
This could mean that there is a broken trace somewhere between port 2 and the CIA chip at location U1. Or it could mean that the chip itself is faulty. Or it could be that the pins from port 2 has broken somewhere between the external pins and the motherboard. Perhaps just some soldering would do the trick. I’m hoping for this – it’s the easy fix. It would then be just like my C128 with its broken power switch. It’s quite plausible actually. The control ports and the power switch have probably all taken some serious physical abuse over the years – joysticks in and out, power switch on and off.
I also tested the SID voices with another of Ray’s programs. It turned out fine to my relief. The three voices of the SID 8580 sounded as they should.
I’ve solved problems before without knowing anything about how to fix them. In this case, I ordered some new control ports from this excellent site. I hope that replacing port 2 will solve the problem. Yes, soldering ahead…