river9999uk Posted March 19, 2022 Share Posted March 19, 2022 Repairing a Secam French Colecovision (thats why the colours are wrong as I am using in on a PAL TV) with what I think is some sort of VRAM issue. I've replaced the VRAM with 4164 ram and done the 5v mod. However the graphics issue with lines and corruption continues. I have cleaned the switch and checked the voltages which are fine on the PCB and at the RAM. Running the diagnostic rom I get the VRAM error fail always at the same location. Anyone have any clues as were to look next? Quote Link to comment Share on other sites More sharing options...
river9999uk Posted March 26, 2022 Author Share Posted March 26, 2022 Just for info I tracked this down to 3 out of my 4 coleco power supplies only getting 4.6-4.7v max to the board. My 4th power supply got 4.8v to the board at the graphics issues went. Despite the power switch being taken to bits and cleaned and the pcb being recapped the power socket to ram circuit dropped around .2v and this was enough for the secam pcb to show these issues. Oddly my 3 other PAL colecos were quite happy with voltage of 4.6v and worked fine. Must be something to do with the secam RGB output perhaps ? Either way mystery solved. Quote Link to comment Share on other sites More sharing options...
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