Repair/Restore my Nintendo M82

you would need to get the scematics and then use that to continuity test all board traces and see if they are ok or broken

 

Or just follow the traces on the actual board. No need for schematics

 

It'd be nice to hook up /IRQ to the cartridge port if that is possible - even though I haven't had an NES for a long time, I'm curious whether that's possible.

I think the other thing that the PlayChoice doesn't support is the color emphasis system. Games which set the color emphasis bits won't be the right color. Unlike an /IRQ line, I doubt that it's possible to fix this one. Well, actually, I suppose that you could make a CPLD that sniffs the bus for writes to this bus, then have it mess with the RGB signal coming out the PPU.

I'm sorry if I'm wrong about the PlayChoice having an RGB PPU.

 

Yeah the playchoice has an RGB PPU. It was previously the only way to get the NES to display over s-video/RGB (scart).

Now there's the NESRGB which I highly recommend (I installed it in my toaster and it is incredible):

http://shmups.system11.org/viewtopic.php?f=6&t=47617

Here's info on the M82 and not all games working (from Bunnyboy's PDF):

Someone once suggested to me that to get games that need the IRQ line to "try running a wire from pin 15 on one of the cart slots to pin 32 of the CPU".

I can't verify if that works or not though since I still haven't gotten my M82 to accept controller input.

 

You need to actually listen and check out that trace or send it to someone who knows what they're doing.

 

Which trace? I'd gladly check it out if you could give me an idea of what I need to check out.

I replaced the socket the Texas Instruments chip plugs into so I'm not that inept!

 

Hey guys, I realize this thread is dead and I apologize for bumping it, but I am at a loss for what could be wrong. Again, games boot fine, but I cannot get controllers to work.

I have traced every pin in the controller port panel. I traced the ribbon cable to the bottom of the motherboard. I get continuity.

I took a LOT of hi-res photos of the bare motherboard.

http://imgur.com/a/uaSUU

Zooming in on the pics should help.

If you look on the pic before the 1st containing the controller board, there's a weird round silver thing (next to a black rubbery piece). What is that? It says K88 (and then is cut off) in the pics.

If no one notices anything obvious, can someone give me an idea of what I should be tracing to make sure everything is okay?

 

I wonder how much it would be to get a new PCB made, then just swap the components over to the PCB??

 

The bottom of the board does have a lot of bubbles, yes, but it's weird. It seems to only be in places that are empty.

It doesn't seem like any water or heat damage damage, it looks like it's just like that? Can KingArthur recall if the bottom of his looked like that? And why would just the bottom look like that, but not the top?

Also I would imagine if all the traces were actually lifted (I don't see that but I am sure I can just be missing something)....wouldn't nothing work? I get sound, video, timer works, games switch, but the controllers wouldn't work? Isn't it more likely that something else (or everything) would go instead?

 

looks like water damaged PCB combined with high temperatures, that afaik is what causes the bubbles to form, heat damage like that can also cause damaged pads/lifting traces

 

That's not water damage, to me it's just a bad solder mask from factory, the trace under are still fine.
Usualy only happend on BIG gnd or power plane, I won't be worried about it at all

 

Yeah again I don't think it's corrosion or even any traces are lifted? Continuity between top and bottom of the motherboard seems to be fine?

I really do think it's something that has to do with a chip that relates to the controller inputs or maybe even the controller input board itself (or where that plugs into). Could it be something as stupid as that sole capacitor on the front of the 5 port controller board?

 

Take that NES CPU out (2C03) and test on a NES. The controller inputs are in it.

 

Just took apart an NES I bought just for this. There is no 2CO3 on it. There is a 2C02 and a 2A03.

On the M82 board itself there also is no 2C03; there's a 2CO2 and a 2A03 there as well, though. Since the 2C02 is the PPU I assume I should be swapping the 2A03s?

 

I meant 2A03, whatever.

Test it on a normal NES.

 

Well I swapped the CPUs (that was fun!) and still no dice. Same exact behavior.

However, a new finding that I am hoping can help me solve this. If I repeatedly plug and unplug the ribbon cable from the 5 port controller board, games will sometimes start/pause. So basically I put on Pro Wrestling (one of the games that came with the M82), and if I keep plugging and unplugging the rainbow-colored ribbon cable, it will sometimes hit "start". In game, it will pause.

I assume this is a good thing as I am narrowing things down, but I am not half as smart as you guys. Any ideas what I should try next?

 

It's nothing to worry about - that is exactly the effect you get when you wave solder a board and the wave height is slightly high - sometimes you don't even have a choice, and if you reduce the wave to the point where it doesn't get under the resist, then the solder doesn't penetrate to the top of the board properly.

This is also why it's only on the underside of the board - the top was never exposed to the solder wave.

This used to be quite common - you don't see it as much now because wave soldering has been largely replaced by reflow soldering and in the case that you have a board that's going to be wave soldered then people will normally avoid solid copper and used a hatched groundplane instead.

 

Definitely not the cable because I had a floppy drive cable laying around and I stuck it in there (the holes lined up perfectly) and still no dice.