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Colecovision Green Screen Problem

Colecovision troubleshooting problem

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#1 TheSolderMonger OFFLINE  

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Posted Tue Jun 12, 2018 11:30 AM

Recently I had acquired a Colecovision, and hadn't gotten around to plugging it in because I had no games. Once I got some games and tried to play, the CV's RF output had a green tint, and looked as if I was playing on a GameBoy screen. There was no color, and all the graphics were just various shades of green! I tried to reflow solder on the RF board to no avail, de-soldered and checked the RF board and the components underneath (no difference), cleaned the power switch (which did not work) and even tried poking around the graphics chip and saw absolutely no difference in color whatsoever. I'm at wits end trying to figure out what is wrong with this CV. 

 

Attached below are a couple of pictures from the system on my Trinitron TV. This also came up on a flat screen TV as well.

 

Any ideas?

Attached Thumbnails

  • 20180612_1222131.jpg
  • 20180612_122521.jpg


#2 TheSolderMonger OFFLINE  

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Posted Wed Jun 13, 2018 1:45 PM

I have a suspicion that the main graphics chip is faulty, and I do have a spare SEGA SG-1000 II to swap the chip from in order to test, but I'm wondering if it could be a RAM issue or a failure elsewhere...



#3 TheSolderMonger OFFLINE  

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Posted Thu Jun 14, 2018 3:49 PM

I managed to hook up an AV mod to it, and the video only tosses out a blank screen, even with a game plugged in! So I am not sure if the graphics is failing or the my wiring is faulty.



#4 TheSolderMonger OFFLINE  

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Posted Thu Jun 14, 2018 4:43 PM

I managed to hook up an AV mod to it, and the video only tosses out a blank screen, even with a game plugged in! So I am not sure if the graphics is failing or the my wiring is faulty.

Update: After some corrections on my soldering, I was able to get a color screen (somewhat) however the pad for the video output came off, and soldering a jumper wire and some more soldering caused the green screen to come back. So I think I found the trouble area for the green screen.



#5 TheSolderMonger OFFLINE  

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Posted Fri Jun 15, 2018 12:10 PM

FINAL UPDATE:

 

Due to severe solder pad damage stemming from bad corrosion and efforts to backtrace the green screen problem going wrong, I will have to declare the CV's time of death at 1:08 PM CST. The main board and the case will be used for parts when I get another unit.



#6 -^CrožBow^- OFFLINE  

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Posted Fri Jun 15, 2018 2:20 PM

the CV is a delicate beast. I'm may not be an electrical engineer, but I would like to think I know my way around a soldering iron pretty well as I use them often at home on my projects and at work.

 

But the CV is one console I really have to take my time with. I make sure the station is set no hotter than about 320 - 330C else as you saw, the pads tend to left and become one with the solder you are trying to pull. 

 

I would even go so far as to recommend only working on a CV main board if you have a hot air station as that is safer in dealing with the CV and its delicate traces and pads.



#7 TheSolderMonger OFFLINE  

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Posted Fri Jun 15, 2018 3:56 PM

the CV is a delicate beast. I'm may not be an electrical engineer, but I would like to think I know my way around a soldering iron pretty well as I use them often at home on my projects and at work.

 

But the CV is one console I really have to take my time with. I make sure the station is set no hotter than about 320 - 330C else as you saw, the pads tend to left and become one with the solder you are trying to pull. 

 

I would even go so far as to recommend only working on a CV main board if you have a hot air station as that is safer in dealing with the CV and its delicate traces and pads.

Thanks for the advice, I'll take this as a lesson learned and try a lighter tip on the soldering iron and thinner solder.



#8 orrko8791 OFFLINE  

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Posted Mon Jun 18, 2018 1:28 PM

Also,next time around keep in mind that on the CV RF Modulator there are 2 adjustment screws-1 for audio/1 for screen(fine tune adjustment) this may clear the problem,

on the modulator you will see a third hole to the left it is a fastener only(it does not adjust)

the 2 adjustment screws are basically located top right and bottom left of each other

these are very small hole opening with the adjustment screws inside

See Enclosed Picture Of Colecovision RF Modulator Enclosed With Adjustment Areas

Attached Thumbnails

  • Colecovision-RF-Alignment-Map-768x612.jpg

Edited by orrko8791, Mon Jun 18, 2018 1:37 PM.


#9 Taijigamer OFFLINE  

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Posted Thu Jun 21, 2018 4:40 PM

If you live in the UK and want someone to have a look at it, I would be happy to do so.







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