NightSprinter Posted February 9, 2006 Share Posted February 9, 2006 Well, since I've a couple of these and they seem to be rather fixable I just want to post some progress on repairing a couple of "dead" C64 units I have. The first one will in fact boot to the BASIC screen. Unfortunately the screen has no color and thick vertical black stripes. Second, any cartridge that's inserted (like my Epyx FastLoad) will cause nothing but garbled characters on the screen upon booting. The last problem is that no disk or cassette games will load completely or even run. I've verified this with Datasoft Pac-Man on disk (gives an error at linke 65535?), Konami Pooyan on tape, and Eypx Jumpman Junior on disk (screen just hangs). My guess is that the CIA chips have gone completely bad, even with the discoloration on the physical chip itself. I may have to replace the CPU and/or the PLA chips as well. The second one just gives me that dreaded "black screen" when booting. So this one I'm guessing it's just the PLA completely as having swapped the 6510 processor from the semi-working one to the non-working one didn't do a thing. I'll keep posting until I can successfully fix them. Thankfully the fully-dead board is socketed, so that makes replacing the chips easier. (Yes, I honestly suck with a soldering iron..) Quote Link to comment Share on other sites More sharing options...
tta583 Posted February 9, 2006 Share Posted February 9, 2006 I'm glad you brought this up, it sparked a memory. Any idea where I can get diagrams for a 64 and a 1541 drive? Perhaps a good C64 discussion boards? I have been thinking about pulling my C64 out of the closet for a little while now. This one is not a thrift store find, its my original unit from back in the day before I got my first PC. Complete with all my games, my old FastLoad, a 1541, a 1541 II, and a monitor and God only knows what else I shoved in that old box (Actually, the same box that first PC came in. It was kind of like a changing of the guard that day.) Anyway I recently picked up a few loose carts, 2 1541's, and a tape drive (had not messed with one of those since I had a VIC). One of the 1541's powers up but never did the startup head seek that I remember. I soon smelled smoke. When I opened it up I found the failed component, a small capacitor I think it is. Should be easy enough to fix unless it is the symptom of a bigger problem. Quote Link to comment Share on other sites More sharing options...
NightSprinter Posted February 9, 2006 Author Share Posted February 9, 2006 (edited) Well, this is what I found so far when I did a search for what caused a black screen in a c64: C64 Troubleshooting Sheet Not sure about a 1541. I just hope the Datasoft disk version of Pac-Man isn't screwed up from trying it in my 1541 since there's an A800 version on the opposite side. [update 1] The screen now has color from swaopping out the CPU. Inserting the FastLoad Cartridge causes a garbled screen unfortunately. The Datasoft version of DigDug managed to get to the copyright screen, but the program hung there. I just tried Pac-Man, and it WORKED!! (need to try Jumpman Junior and Dig Dug again). So it would seem that at the VERY least I need to replace the PLA chip (might have to swap the CIA chips since they're showing some grey when it's supposed to be black color on the chips). I'll further update after class. Edited February 9, 2006 by NightSprinter Quote Link to comment Share on other sites More sharing options...
NightSprinter Posted February 9, 2006 Author Share Posted February 9, 2006 TTA, I just managed to find a diagnostic chart of the 1541 and any symptoms you might have with it: Commodore 1541 Tips Use it in good health. Quote Link to comment Share on other sites More sharing options...
+remowilliams Posted February 9, 2006 Share Posted February 9, 2006 The PLA is the most common chip to drop dead. I've replaced a bunch of those for people over the years. Word of advice - if you get the whole thing working - heat sink the damn PLA chip Quote Link to comment Share on other sites More sharing options...
NightSprinter Posted February 10, 2006 Author Share Posted February 10, 2006 Any advice on how to do so for the non-socketed one, Remo? I know that the metal RF shield on my socketed C64 also doubles as a heatsink (I've found thermal grease on the chips). Quote Link to comment Share on other sites More sharing options...
+remowilliams Posted February 10, 2006 Share Posted February 10, 2006 Most of the ones I replaced were not socketed. So I usually clipped the bad ones off (then desoldered the left over pins) and then soldered in a socket for the new ones. Unfortunately there isn't any easier way around that Easiest way to get better at it is to find a victim board and just keep trying to desolder chips off it until you get better at the whole process. The RF shield does function as a "better than nothing" heatsink. If you bend the tab down and add thermal grease, it'll operate a little better, but a small machined heatsink is still the better way. Quote Link to comment Share on other sites More sharing options...
AussieAtari Posted February 10, 2006 Share Posted February 10, 2006 You might try go64.de and cbm.videocam.net.au for plenty of C64 hardware info and links. Quote Link to comment Share on other sites More sharing options...
Osbo Posted February 10, 2006 Share Posted February 10, 2006 radioshack sells a pump to desolder that works like a champ. I fixed two C64s with parts donated by another one (one had a bad PLA and the other had a bad 6510) Quote Link to comment Share on other sites More sharing options...
tta583 Posted February 10, 2006 Share Posted February 10, 2006 This may be of some help as well. http://project64.c64.org/archive.htm Click on the c64. Quote Link to comment Share on other sites More sharing options...
+remowilliams Posted February 10, 2006 Share Posted February 10, 2006 radioshack sells a pump to desolder that works like a champ. I fixed two C64s with parts donated by another one (one had a bad PLA and the other had a bad 6510) 1016255[/snapback] Yeah, that thing is handy at times. One of the problems with it is the stupid heat nozzle wears out after a while and they don't sell replacements. And for finer work, you still need a solder sucker. Quote Link to comment Share on other sites More sharing options...
Osbo Posted February 11, 2006 Share Posted February 11, 2006 radioshack sells a pump to desolder that works like a champ. I fixed two C64s with parts donated by another one (one had a bad PLA and the other had a bad 6510) 1016255[/snapback] Yeah, that thing is handy at times. One of the problems with it is the stupid heat nozzle wears out after a while and they don't sell replacements. And for finer work, you still need a solder sucker. 1016460[/snapback] yeah I had that problem, the way I do it, I heat the solder on chips side of the motherboard and I use the pump in the other side, works most of the time, taking all the solder clean out. Quote Link to comment Share on other sites More sharing options...
Rockin' Kat Posted April 5, 2006 Share Posted April 5, 2006 When I first got my C64 it had a problem where one of it's input controller IC's died. I was able to get help in diagnosing it and then find someone with a replacement CIA chip(there are two of them and one of them died to make it so I could not use the keyboard or game ports) using the C= Homestead mailing list. Quote Link to comment Share on other sites More sharing options...
Artlover Posted April 5, 2006 Share Posted April 5, 2006 radioshack sells a pump to desolder that works like a champ. 1016255[/snapback] One of the problems with it is the stupid heat nozzle wears out after a while and they don't sell replacements. Eh? I've always been able to buy replacements for mine. Quote Link to comment Share on other sites More sharing options...
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