teknohed Posted August 11, 2021 Share Posted August 11, 2021 Hi Gang. I have a colecovision that is powering on, but is just displaying a black screen. I know it comes on and tries to display something because on RF it switches from snow to "black screen" and on Composite it goes from "no signal" on my AVR to "black screen" when powered on. Here is what I have done: 1. replaced capacitors entire system with console 5 cap kit 2. disassembled and cleaned the power switch 3. reflowed solder to cart slot and VDP 4. Tested OEM power supply and it appears to have correct voltages 5. purchased a USBCOL power supply which doesn't resolve the issue 6. I did install a composite mod, but I am not getting video out of the RF either, so I dont think that is the problem. I have also purchased but have not installed replacement Video Ram, Bios chip, and Controller chips from Console 5. I also bought a new rocker switch to replace the power switch. Anyone have any other ideas for things I could try that I have not? Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted August 11, 2021 Share Posted August 11, 2021 Is there a standing tone when you turn it on? Do you have Frogger? Does it start playing music as soon as you turn on the console? Quote Link to comment Share on other sites More sharing options...
teknohed Posted August 11, 2021 Author Share Posted August 11, 2021 I am not hearing any audio. And I do not have a copy of frogger. Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted August 12, 2021 Share Posted August 12, 2021 Do you have a multimeter? oscilloscope? Quote Link to comment Share on other sites More sharing options...
teknohed Posted August 12, 2021 Author Share Posted August 12, 2021 Hi. I have a multimeter but not an oscilloscope. Tonight I did some testing based on the trouble shooting on console 5’s VRAM install guide. I check continuity between the pins on the VDP and the VRAM chips. I also checked the VRAM chip voltages. Everything looked within spec. Not sure what else to check. I also have checked the power supply and the point where the power cables meet the board and the voltage ther is good. I still think it might be the power switch even if I cleaned it. But I don’t know, just because there are no bad traces between the vram and the vdp doesn’t mean that one of those chips aren’t bad. Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted August 12, 2021 Share Posted August 12, 2021 You usually get junk on the screen if the VRAM is bad, not a black screen. If any cartridge is in the slot, wait at least 12 seconds and then press the 1 key. That should start the game, so you can listen for any sound. If nothing at all happens, it could be that the SRAM is dead. Quote Link to comment Share on other sites More sharing options...
teknohed Posted August 12, 2021 Author Share Posted August 12, 2021 I will check that. Thank you!!!! Quote Link to comment Share on other sites More sharing options...
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