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Another Colecovision video issue thread

1 reply to this topic

#1 Ramses OFFLINE  


    Chopper Commander

  • 219 posts

Posted Wed Aug 8, 2018 8:29 PM

My AV modded (LM318) Colecovision is on the fritz. I'm guessing it's the VRAM. It started having problems after a power outage a while back which makes the power switch seem like an unlikely culprit. It began with small little graphical glitches here are there and progressively got worse. I tested the power supply and the readings seemed good. Audio works fine along with the inputs. I've attached a sample screen of Donkey Kong.


Given this info am I correct in assuming that it's probably a VRAM issue? What should be my next steps? I've never had any luck with desoldering my Colecovision or Atari 800XL in the past so I'll need to find someone who would be able to fix it.

Attached Thumbnails

  • Colecovision.jpeg

Edited by Ramses, Wed Aug 8, 2018 8:30 PM.

#2 Taijigamer OFFLINE  


    Chopper Commander

  • 106 posts

Posted Thu Aug 9, 2018 3:38 PM

Use this page from the service manual for tips http://www.colecovis...ision tech4.pdf. Check for activity from the VRAM pins on the TMS9928 (U9). Most likely VRAM as you said or a bad 9928.

Edited by Taijigamer, Thu Aug 9, 2018 3:56 PM.

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