Grey screen. Probably my fault. Can it be revived?

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Grey screen. Probably my fault. Can it be revived?

Post by Grinlord » Mon Dec 28, 2020 1:48 pm

I dabble with soldering projects but have little experiencing repairing things at a component level. I recently pulled my unmodified one-owner NES out of storage to setup a retro gaming room in my loft, which has been great, except for the NES.

Initially it would only play some games with repeated re-inserting of cartridges and a squirt of contact cleaner.

I did some research and found out how to cut the pin of the 10NES chip. This was successful, so I now knew that this chip wasn't the culprit.

I did some more research and learnt how to bend the cartridge side of the 72 pin connector to make better contact. This helped a bit. I then learnt to boil the 72 pin connector. While it was apart I cleaned the contacts on the motherboard, but this is where I messed up. Without reading first, I assumed that nail varnish remover and a fibre pen would dissolve and clean the contacts, but I have since learnt that the acetone in the nail varnish remover was potentially very harmful. Now I can not make any game boot up. I just get a solid grey screen.

I bought a new cheap 72 pin connector but this didn't help. I bought a security torx tool and opened a cartridge, and this time cleaned it with alcohol sanitiser (over 75% alcohol) and cardboard. I did the same to the motherboard contacts and produced a good shine on both. I tested the cartridge end of the 72 pin connector for continuity on every pin to the motherboard and this passed, but still the cleaned game won't boot. I tried two other games for good measure which also wouldn't boot. This is what my motherboard and the cleaned game look like now:
MB top.jpg
MB under.jpg
cart top.jpg
cart under.jpg
I boiled the original 72 pin connector again and refitted it, and again it passed continuity to the cartridge end, but didn't help the problem.

I found the following post on here about someone who had the same symptoms (but not necessarily self inflicted damage), and eventually diagnosed a faulty RAM module. I don't know how to test this:

I also don't know if these solder joints look suspect?
poss bad joints.jpg
I have tested my external PSU and verified 10vac unloaded. Not sure what voltages I should probe for inside.

Hope you can help me revive my original NES without having to replace it.

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