zylon Posted March 25, 2010 Share Posted March 25, 2010 I'm down to one working vic-20 Does anyone here still fix them? My broken one is the later style with the colored logo bar and C64 style power supply. I was using it for about an hour and turned it off to change the game. When I turned it back on, all I got was a scrambled black/grey screen and AM radio through the tv. Quote Link to comment Share on other sites More sharing options...
nathanallan Posted March 26, 2010 Share Posted March 26, 2010 I'm able to fix them, but AM radio through the TV set? That's weird, but cool at the same time. You may want to try over at vintage-computer, but if all else fails I bet I could get it fixed for you. Nathan Quote Link to comment Share on other sites More sharing options...
+save2600 Posted March 26, 2010 Share Posted March 26, 2010 Have you tried opening her up and reseating all the chips? Quote Link to comment Share on other sites More sharing options...
zylon Posted March 26, 2010 Author Share Posted March 26, 2010 (edited) Yep, tried the chip resetting. The big one had a bit of white corrosion on it, but made no difference. These are getting tougher to find in working order so fixing one may be a viable option. Unfortunately, this one only seems to get talk radio Edited March 26, 2010 by zylon Quote Link to comment Share on other sites More sharing options...
+save2600 Posted March 26, 2010 Share Posted March 26, 2010 (edited) Yep, tried the chip resetting. The big one had a bit of white corrosion on it, but made no difference. These are getting tougher to find in working order so fixing one may be a viable option. Unfortunately, this one only seems to get talk radio LOL! Talk radio BTW: That white "corrosion", was it gummy and sticky? That's not corrosion, that's heat sink compound designed to keep the Vic chip nice and cool. Did you wipe all that stuff off before your system blew? IF so, might be a chance you unknowingly sealed that chips fate Edited March 26, 2010 by save2600 Quote Link to comment Share on other sites More sharing options...
zylon Posted March 26, 2010 Author Share Posted March 26, 2010 Yep, tried the chip resetting. The big one had a bit of white corrosion on it, but made no difference. These are getting tougher to find in working order so fixing one may be a viable option. Unfortunately, this one only seems to get talk radio LOL! Talk radio BTW: That white "corrosion", was it gummy and sticky? That's not corrosion, that's heat sink compound designed to keep the Vic chip nice and cool. Did you wipe all that stuff off before your system blew? IF so, might be a chance you unknowingly sealed that chips fate Good guess, but not quite. The corrosion was on the prongs of the chip. The chips in this system are not under a heat shield and none have evidence of the heatsink goo, even the one inside the small shielded box. The only time I'd wipe that off would be to read numbers for a replacement. Quote Link to comment Share on other sites More sharing options...
+save2600 Posted March 26, 2010 Share Posted March 26, 2010 (edited) Only other thing I'd do before moving on to testing circuitry and power is to clean the pins on those chips and investigate their sockets. Clean the chips with some super fine grit sandpaper if they're corroded. Pencil erasers and the like are not going to do the trick against oxidation, although I hear people recommending that method from time to time. You could even try spraying the sockets with contact cleaner - NEVER WD-40! Oh and make sure the solder joints on the power connector and throughout the main board are all good. I recently had to touch up some cold solder on a couple Commodore and one Atari product before they'd work. Never heard any AM radio through 'em though... lol Edited March 26, 2010 by save2600 Quote Link to comment Share on other sites More sharing options...
zylon Posted March 27, 2010 Author Share Posted March 27, 2010 At least my 2600 L6er got the oldies station! Quote Link to comment Share on other sites More sharing options...
+save2600 Posted March 27, 2010 Share Posted March 27, 2010 At least my 2600 L6er got the oldies station! LOL! Are you serious? Okay, I'm starting to notice a pattern here... you live by some heavy duty power lines or radio station by any chance? lol Not unlike all these modern cars that suddenly speed up over EMI from power lines in CA... Quote Link to comment Share on other sites More sharing options...
zylon Posted March 27, 2010 Author Share Posted March 27, 2010 There's a power transformer 3 houses up. It used to be in front of my house but it got hit by lightening every couple years. The 2600 had bad sound caps. After I replaced them, the problem disappeared. Quote Link to comment Share on other sites More sharing options...
Ben_Larson Posted March 28, 2010 Share Posted March 28, 2010 I'm down to one working vic-20 Does anyone here still fix them? My broken one is the later style with the colored logo bar and C64 style power supply. I was using it for about an hour and turned it off to change the game. When I turned it back on, all I got was a scrambled black/grey screen and AM radio through the tv. I had the same symptoms on my vic-20 (except for the AM radio ). The problem was that the little RF modulator box that hooks it up to the TV was going bad. I replaced the electrolytic capacitors inside it with some equivalent ones I bought at radio shack and it works fine now, for what that's worth... Quote Link to comment Share on other sites More sharing options...
nathanallan Posted March 28, 2010 Share Posted March 28, 2010 I'm down to one working vic-20 Does anyone here still fix them? My broken one is the later style with the colored logo bar and C64 style power supply. I was using it for about an hour and turned it off to change the game. When I turned it back on, all I got was a scrambled black/grey screen and AM radio through the tv. I had the same symptoms on my vic-20 (except for the AM radio ). The problem was that the little RF modulator box that hooks it up to the TV was going bad. I replaced the electrolytic capacitors inside it with some equivalent ones I bought at radio shack and it works fine now, for what that's worth... That's an idea. Do you have AV cables for it? Or another RF modulator? Worth a shot to see if that's the problem. Still willing to work on it, though. Nathan Quote Link to comment Share on other sites More sharing options...
zylon Posted March 28, 2010 Author Share Posted March 28, 2010 I have 3 Vic modulators and a few TI99 modulators as well. Same result with all of them. Also tried my homemade AV cable and got just black screen. I retested the modulators on the TI and my C64 and they all worked. At least something's still good! I was using the same power cord on my 64C and that still works so I can rule that out also. Quote Link to comment Share on other sites More sharing options...
channelmaniac Posted March 31, 2010 Share Posted March 31, 2010 Check for proper +5v on the SRAM chips. Beyond that, the VIC can give those symptoms with a variety of different bad chips: VIC, CPU, SRAM, 6522 VIA, or Kernal ROM. Unplug the BASIC ROM and the Character ROM one at a time and power it up without those in. If those are shorted on an output then you'll have those symptoms and the system can boot without them. Try a cart with it to see if it works. Maybe you have a bad SRAM, Kernal, or BASIC ROM. Worst case, if you can't figure it out, I can do repairs on it for you. I do flat rate repairs on the old school computers. RJ Quote Link to comment Share on other sites More sharing options...
zylon Posted April 7, 2010 Author Share Posted April 7, 2010 (edited) Update: I've managed to get the one older-style Vic working. It takes around 10 seconds then the black screen changes to the ready one. I cleaned a bunch of stuff, reseated chips, remounted lower shielding. Don't know what I did right. My good one turns on in about 1sec, so this one isn't quite right yet, but closer. The later 64-style one is still down... Edited April 7, 2010 by zylon Quote Link to comment Share on other sites More sharing options...
nathanallan Posted April 7, 2010 Share Posted April 7, 2010 I bet it was the reseating of the chips that did it. PM replied, let's get them both on the road Quote Link to comment Share on other sites More sharing options...
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