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alpha_male

Colecovision repair - scrambled screen to no output at all

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Hi everyone,

Looking to pick the community brain. I found a Colecovision that belonged to my brother in law in the 80's. He packed it away like 30 years ago and the thing looks mint, he was one to take care of stuff. So I tried it out to see if it still worked. I got a black screen for the 12 seconds and an extremely scrambled game select screen lots of vertical lines and random letters. I can select a game and hear music and sound and see movement but the screen is so scrambled, games are unplayable. So knowing about the common power switch and power supply (I have the Canadian model), I took the switch apart and cleaned it and gave it some fresh dielectric grease. The only change was now the black screen had some random letters on it instead of blackness, everything that followed was the same as before so. I clean the carts and cart port and the entire circuit board with alcohol. I put a multimeter to the power supply and had +5v, -2v and +10v so I thought maybe the power supply had an issue, I cracked it open and cleaned the board and then I had proper voltage output, +5. -5 and +12. I plugged it in, and now it won't even output a signal. The power coming into the unit on the back side of the AC connector while the console is powered on is reading +12V, -2V and +1V, not sure if that normal to be that low. I'm just wondering what to do next. My soldering ability is pretty basic and so is my fault finding with the multimeter. I am a medical equipment service tech by trade but we never work on circuit boards because the industry's service is based complete board swap out rather then fault finding on broken board for liability reasons. I'd love to learn more about troubleshooting this Coleco board but I can't find that anyone has run into this particular problem. Any suggestions?

 

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It might be the vdp memory chips on the board are actually gone bad with time. If you had a second working coleco system you could try out the various parts quickly to see if it's a cart, the power supply or the actualy system. I find that a very helpful way to narrow things down.

 

Are you on the right channel? using those old rf boxes could also be the problem. get one of these :

https://www.ebay.ca/itm/1-Atari-2600-Colecovision-Intellivision-Coaxial-RF-Video-Adapter-TV-Quick-Ship/372144866186?hash=item56a590038a:g:RR8AAOSwrWxZcMPb

 

if it's the memory chips you can solder new ones in with sockets:

https://console5.com/store/colecovision-5v-memory-upgrade-kit.html

 

or just by pass that altogehter and get an f18a upgrade and run it out to vga.

 

There is also a new colecovision compatible console coming out soon that you can just replace the mother board in your system.

 

I wouldn't do any surgery til you 've tried swapping working parts inlcuding the power supply etc from a good system if you know anyone with one.

 

It can be fixed. I've done it myself so keep at it.

 

Hi everyone,

Looking to pick the community brain. I found a Colecovision that belonged to my brother in law in the 80's. He packed it away like 30 years ago and the thing looks mint, he was one to take care of stuff. So I tried it out to see if it still worked. I got a black screen for the 12 seconds and an extremely scrambled game select screen lots of vertical lines and random letters. I can select a game and hear music and sound and see movement but the screen is so scrambled, games are unplayable. So knowing about the common power switch and power supply (I have the Canadian model), I took the switch apart and cleaned it and gave it some fresh dielectric grease. The only change was now the black screen had some random letters on it instead of blackness, everything that followed was the same as before so. I clean the carts and cart port and the entire circuit board with alcohol. I put a multimeter to the power supply and had +5v, -2v and +10v so I thought maybe the power supply had an issue, I cracked it open and cleaned the board and then I had proper voltage output, +5. -5 and +12. I plugged it in, and now it won't even output a signal. The power coming into the unit on the back side of the AC connector while the console is powered on is reading +12V, -2V and +1V, not sure if that normal to be that low. I'm just wondering what to do next. My soldering ability is pretty basic and so is my fault finding with the multimeter. I am a medical equipment service tech by trade but we never work on circuit boards because the industry's service is based complete board swap out rather then fault finding on broken board for liability reasons. I'd love to learn more about troubleshooting this Coleco board but I can't find that anyone has run into this particular problem. Any suggestions?

 

Edited by digress

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Those voltage measurements with the CV on don't sound normal to me, but I've never done much at the board or component level.

 

I usually try to swap a different (hopefully known-working) part, but you probably don't have an extra CV PS hanging around...know someone who has a working CV?

 

If you are able, you could use alligator clips to connect alternative PS for the correct voltage/amps (being an equipment tech, you might have a variable power supply?)

 

If you want to really dig in, you can trace the voltage measurements on the board, but that's pretty hard core.

 

The symptoms on the screen might occur from a dirty cart, or slot. Might make sure the power plug is clean also. Cleaning the switch was a good idea. Could also be bad memory chips. Maybe someone else will comment...

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One of the 4116, U17, looks scorched to me. I've picked up an as-is console on ebay today so hopefully I can get one of them working.

Edited by alpha_male

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