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View topic - GameGear black screen - replaced caps

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  • Joined: 16 May 2018
  • Posts: 3
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GameGear black screen - replaced caps
Post Posted: Wed May 16, 2018 7:11 pm
Hi!
A while back I bought a used GameGear from somewhere. It had major corrosion in the battery compartment (most of the battery terminals were destroyed) and didn't turn on at all when plugging in a power adapter.

So I began by going the classic route when dealing with any old hardware - I replaced all of the electrolytic capacitors (on all boards). There were signs of electrolyte leakage, but I managed to clean all of the residue and no damage was visible. So I tried powering it up again - it didn't work. After nosing around I found out that it's probably the power jack or something near there since applying power directly to the battery terminals (from a bench power supply) did work.

Except not quite... The power LED turns on, the game starts running (pressing the buttons makes game noises), the backlight turns on, the sound is present, ... Except the screen stays black. No pattern or anything. It's just black. After some fiddling around I figured out that spraying contact cleaner into the contrast potentiometer and then turning the thing on and off made thing work occasionally. The screen turned on and I could play the game without any issues. Except that only worked a few times. I can't replicate that anymore.

So after measuring the power supply board I figured out that 35V (I think - can't remember the exact voltage) rail was missing. So I just ordered a replacement board (after all I had a non working power jack as well) hoping that it will solve my issues. It sadly didn't. The screen still isn't working.

Any ideas on what else could be wrong?
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  • Joined: 05 Nov 2014
  • Posts: 151
  • Location: Auckland - NZ
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Post Posted: Thu May 17, 2018 2:07 am
Does the contrast pot still measure good? Ive had similar issues and it was an open pot.
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  • Joined: 16 May 2018
  • Posts: 3
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Post Posted: Fri May 18, 2018 5:37 am
I forgot to mention that... l I measured the resistance between the two upper pins on the pot and it measured anywhere between 6k to 15k (it's a 20k pot if I am not mistaken?) while I was playing around (I didn't measure the endpoints). So the pot looks good. I haven't actually checked which traces are connected so I am not sure if those two pins are correct. Sadly I am on a trip for a few days so I can't really check it again right now. But I will double check when I come back.
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  • Joined: 16 May 2018
  • Posts: 3
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Post Posted: Tue May 22, 2018 5:29 am
Well I checked it again... The pot measures between 0 ohms to 15k.
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