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Any NES console repair techs here? Static garbage image.


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If the game isn't running at all, I'd at least assume the PPU is working fine, as it's able to render recognizable characters from the CHR ROM.

Doesn't take a genius I guess, but it looks it looks to me that the CPU isn't running the game properly, and from my knowledge of the system's hardware (mostly from a dev perspective) I'd say what you're seeing looks very much like just the contents of uninitialized PPU nametable memory. Basically what you'd get if you ripped the program ROM out of a cartridge, and put in what remains.
The cause of this can be a lot of things, but it allows us to at least rule out some potential issues.

The most obvious culprit is always the cartridge connection of course. I'm assuming you're testing with multiple game that have all been cleaned as much as they can?
In case it's the cartridge connector on the NES itself, I'd suggest trying to swap out with one from a known working NES just to rule that out before trying anything else.

It seems like you've already done this. Good. 🙂

Secondly, as @bowser pointed out, blown capacitors is a common cause of issues with old console hardware, and they can result in any kind of unexpected issues. Before trying anything else, I'd go over the ones you can find and at least make sure they look fine. Look out for even very slight bulges that shouldn't be there. Caps are very easy and cheap to replace, and old ones are prone to breaking on their own, so it's a good thing to try before anything else.

Third, let's go back to the idea of the cartridge connection. It should be fairly easy to trace a few of the cartridge pins (focusing especially on CPU address and data lines), and I'd try to make sure there are no broken connections on the PCB going to the CPU.

If everything up until this point is in order, I'd pin either the CPU RAM or the CPU itself as the culprit. Let's hope for the RAM, since the latter is a custom ASIC and requires sacrificing other NES hardware to replace. 🙂

Edited by Sumez
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2 hours ago, SNESNESCUBE64 said:

Before you even do anything else, check your voltages. Check the power supply you are using and check the 5V rail on the board if you have a multimeter. If the voltage is too low, it may not boot. If it is too high, that could be troublesome.

Power supply was already swapped out with a known working one. I said that in the very first post.

Edited by smalltownguy2
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I'd check the 5V pin on the actual CPU with a voltmeter, too. It's a very good suggestion.

Even if the PSU isn't the problem any broken component in the console could cause issues. Including the voltage regulator or capacitors.

IIRC the front loader NES's voltage regulator is notoriously flimsy. You need to replace it if you're installing a NESRGB.

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