brninitdwn Posted August 12, 2016 Share Posted August 12, 2016 (edited) Hey everyone, I have been lurking about for a bit to troubleshoot my colecovision but have not been successful. I had previously socketed and replaced the decoder at U16 and put the system up, now when attempting to power on all that appears on the screen are "#1" in two to three spots, I attached a picture. I do have a "donor" board that has a distorted video output but does boot, that board is not in good condition though so I've been trying to bring this one back. Has anyone run across an issue like this? I have the Coleco tech manuals but am unsure what troubleshooting steps to follow as it is trying to show video output. Thanks in advance for any help you can offer Edited August 12, 2016 by brninitdwn Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted August 12, 2016 Share Posted August 12, 2016 Do you have a picture of the board? what Chip did you put in U16? That should be one of the 8 RAM chips(4116) for the VDP. Quote Link to comment Share on other sites More sharing options...
brninitdwn Posted August 15, 2016 Author Share Posted August 15, 2016 (edited) Sorry, I was doing it by memory. I replaced U6 last time. The socket was a bit big so I pulled 2 pins out and soldered the rest, 74LS138 was the chip Edited August 15, 2016 by brninitdwn Quote Link to comment Share on other sites More sharing options...
brninitdwn Posted August 16, 2016 Author Share Posted August 16, 2016 Also I did swap that chip off of the donor board as well but had similar results. Has anyone seen this before? Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted August 16, 2016 Share Posted August 16, 2016 Does it do the same thing with no cartridge inserted? Quote Link to comment Share on other sites More sharing options...
brninitdwn Posted August 16, 2016 Author Share Posted August 16, 2016 (edited) Yes it does, that one was with no cartridge installed. Edited August 16, 2016 by brninitdwn Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted August 16, 2016 Share Posted August 16, 2016 Do you get any sound if you power on with a game and wait and press 1? Quote Link to comment Share on other sites More sharing options...
brninitdwn Posted August 16, 2016 Author Share Posted August 16, 2016 (edited) I power cycled it a few times with the game installed, it was all black once. The second time after pressing 1 this was what happened. The third time I left it alone and head the music from the mouse trap cartridge, this was displayed. Sound was working After pressing 1, sound was working The game was mouse trap. Also I have it at work, I believe the Atari expansion is at home with frogger which I can bring if it will help. Edited August 16, 2016 by brninitdwn Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted August 16, 2016 Share Posted August 16, 2016 Since the sound is working, I would think this is either a power issue (on the 12V or -5V that is only used by the Video RAM) or Video RAM or VDP failure. First thing to try is to clean out the power switch with deOxit or contact cleaner and try it. They sell RAM replacement chips but I would recommend getting a F18a upgrade. It replaces the VDP and uses its own video ram. 1 Quote Link to comment Share on other sites More sharing options...
brninitdwn Posted August 16, 2016 Author Share Posted August 16, 2016 I'll check it out then look into the F18a, thank you for the info! Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted August 16, 2016 Share Posted August 16, 2016 If you need someone to do the upgrade for you, I offer that service. https://www.facebook.com/ColecoVisionUpgradeAndSales/ Quote Link to comment Share on other sites More sharing options...
brninitdwn Posted August 17, 2016 Author Share Posted August 17, 2016 I've got a bad +5 somewhere, pin 9 of the 4116's has 0V but it is working at the board. Quote Link to comment Share on other sites More sharing options...
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