Grinllord

Today I tested that the 5 pins for the power / reset buttons were not bridged in any way. Then I applied insulation tape behind the cartridge connector as suggested, and for good measure used a brand new 12v 2a power supply. I have read and seen it confirmed that the NES will accept a broad range of power inputs because the DC rectifier is internal. I tried my previously disassembled and cleaned SMB2 cartridge, and still just a plain grey screen. I even tried the RF output but no change, and then tried two other random cartridges, but still no change. It seems sad to write this off as I've owned it since new.

Thanks for all your ideas and suggestions. Yes my NES worked before I started doing any repairs and cleaning. Game loading varied from nothing to intermittent to ok, but the console definitely worked. Chopping the pin on the 10NES chip was also successful. I had no further problems after doing this, but it was a great relief to not have any blinking red light issues. I didn't ever use traditional WD40 on this NES, but my contact cleaner is made by the same brand. I realise that multicarts are a great way to enjoy the original hardware, but I love owning and collecting the real cartridges.

Thanks very much for looking at the details. When I did a continuity test of every motherboard contact to the cartridge connector, I only moved one probe at a time which means I would have noticed if one contact was being bridged to the next one. Does this rule out that issue? I don't see how anything in the NES design when full assembled could bridge those contacts, but I am disappointed in my casual mistake earlier on. I might try running it without the metal shield.

Sadly I too am coming to the conclusion that I killed it. Here's the condition of the motherboard connector and a cartridge that a disassembled to clean. This time I'm only using alcohol and a piece of cardboard (I read that this is just abrasive enough to polish without damage). But what does anyone make of these solder joints on the motherboard?

So I just cleaned the motherboard connector with alcohol, then refitted the 72 pin connector and tested for continuity. Every pin was fine. So I cleaned a couple of games with alcohol as well, but still nothing loads. I'm very disappointed if I've killed my NES so easily even though it's my own fault. Next up will be dismantling a cartridge and checking continuity to each pin while it's inserted.

I've just ordered the security torx bits for taking the cartridges apart for better cleaning, so this might help.

Does anyone know where I'm going wrong with improving my NES? I've owned it since new but it's been in storage for 15 years until recently. Some of the games worked but intermittently. The first thing I did was cut the pin to the NES10 chip which worked. Then I manually bent the pins on the cartridge connector for a tighter grip and sprayed some WD40 branded electrical contact cleaner on the cartridges. This helped a bit. Then I removed the 72 pin connector and boiled it as recommended elsewhere, and cleaned the motherboard connector with a fibre pen, then wiped it with nail varnish remover and cotton buds. Since then it hasn't loaded a single game. Just a grey screen. I bought a new 72 pin connector, and cleaned every cartridge with the nail varnish remover and cotton buds, but still no joy. I'm wondering if I've left deposits on the motherboard or cartridge connectors with the fluids I'm using? The WD40 contact cleaner does say it's non-conductive, but that's why I used the nail varnish remover to clean afterwards. I have alcohol cleaner as well but I haven't used that yet. Considering flowing some solder onto the motherboard pins, and then running desolder braid over it to keep the solder area small and flat. Any other ideas?