goldenegg Posted February 25, 2014 Share Posted February 25, 2014 I just received a C64 from a member here. I hooked it up and am not getting any video from it. I've tried both RF and composite. I have another C64 that works fine, with the exact same cables. He insists the system is working and says : I didn't test the RF, but I did test the three way composite on a Commodore 1701monitor before shipping. It does indeed work. Try again, try different cables try blowing into the connectors, troubleshoot the problem. It's not broken. I used a can of compressed air to clean the connectors, but that didn't make any difference. Anyone have any thoughts? I can't think of anything I could possibly be doing wrong. Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 25, 2014 Share Posted February 25, 2014 Is the power LED coming on? C64 has an internal fuse, it might have broken or come loose during shipping. Since you have another C64 I guess you can load tapes and/or disks - you could try typing blind and see if you can get something to load. Quote Link to comment Share on other sites More sharing options...
goldenegg Posted February 25, 2014 Author Share Posted February 25, 2014 The power LED is coming on. I only have a Ultimate 1541-II, so I'm not sure how to properly navigate that blindly. If you have any suggestions, I'd be happy to give them a try. Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 25, 2014 Share Posted February 25, 2014 You could try on the monitor, blind type to get some sound going: POKE 54296,15 POKE 54273,70 POKE 54277,0 : POKE 54278,255 POKE 54276,33 Should give a constant med/high pitched sawtooth waveform. Quote Link to comment Share on other sites More sharing options...
carlsson Posted February 25, 2014 Share Posted February 25, 2014 (edited) Are you using the known good power supply with the new C64? Otherwise you might have received a bad PSU that outputs the voltage required to lit the LED but nothing else. Also, I think in some cases the LED might go on even if the internal fuse is broken, it is worth checking. By the way, is it an old style breadbox or a flat C64C? The older breadboxes are very prone to broken PLA chips (memory addressing) and it is fully possible that it booted when the seller packaged it, and then this chip has gone bad when you received it. One way to test it is to power on/off/on rapidly for a few seconds and leave it on. Sometimes the PLA comes to life and you get a display. Notice that newer C64C generally don't have this problem. Edited February 25, 2014 by carlsson Quote Link to comment Share on other sites More sharing options...
goldenegg Posted February 25, 2014 Author Share Posted February 25, 2014 You could try on the monitor, blind type to get some sound going: POKE 54296,15 POKE 54273,70 POKE 54277,0 : POKE 54278,255 POKE 54276,33 Should give a constant med/high pitched sawtooth waveform. Thanks. I'll give that a try on the weekend. I won't have a chance to use the system again until Saturday. Are you using the known good power supply with the new C64? Otherwise you might have received a bad PSU that outputs the voltage required to lit the LED but nothing else. Also, I think in some cases the LED might go on even if the internal fuse is broken, it is worth checking. By the way, is it an old style breadbox or a flat C64C? The older breadboxes are very prone to broken PLA chips (memory addressing) and it is fully possible that it booted when the seller packaged it, and then this chip has gone bad when you received it. One way to test it is to power on/off/on rapidly for a few seconds and leave it on. Sometimes the PLA comes to life and you get a display. Notice that newer C64C generally don't have this problem. I'm pretty sure I used the power supply from the system that works, but now I'm second guessing myself. I'll make sure to try that when I test the system again. It is the breadbox style, so I'll also try your recommendations to let the system warm up a bit. If the PLA chips have gone bad, can replacements be purchased? Quote Link to comment Share on other sites More sharing options...
goldenegg Posted February 25, 2014 Author Share Posted February 25, 2014 If I want to buy a PLA replacement, who's a trustworthy reseller for the SuperPLA V3? Quote Link to comment Share on other sites More sharing options...
Rybags Posted February 25, 2014 Share Posted February 25, 2014 I've got doubts it's the PLA. That can be gone and you still get video albeit just a blank screen. No video at all, either a power problem, VIC or something in the video circuit. Quote Link to comment Share on other sites More sharing options...
goldenegg Posted February 25, 2014 Author Share Posted February 25, 2014 I've ordered a 8-pin video cable, so I can perform the same test the seller did prior to sending me the unit. Is it possible that RF and composite output don't work, while luminance and chroma does? Quote Link to comment Share on other sites More sharing options...
Seob Posted February 25, 2014 Share Posted February 25, 2014 (edited) Couldn't it be that one of the ic's has come loose out of it's socket during shipping? Try to reseat the ic's. Edited February 25, 2014 by Seob 1 Quote Link to comment Share on other sites More sharing options...
goldenegg Posted February 25, 2014 Author Share Posted February 25, 2014 I believe the model of system I got doesn't have socketed chips. I can confirm on the weekend though. Quote Link to comment Share on other sites More sharing options...
goldenegg Posted February 26, 2014 Author Share Posted February 26, 2014 I had a little bit of free time this afternoon, so I ran some more tests. 1 - I confirmed the system I received doesn't have socketed chips. Everything is soldered to the board, so nothing would have come loose. 2 - I made sure to use the power supply from the known working system and it didn't fix the issue. Still not getting any video output. 3 - I got hold of a 1541 drive and tried to blind load a disk. Nothing happens after entering the load command 4 - I used Rybags' code to try and produce sound, but nothing happened Seems to me that this system is dead in the water. Anything else I could try? Quote Link to comment Share on other sites More sharing options...
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