Tecmo Super Bowl Repair Question

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nintendoafterparty
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Tecmo Super Bowl Repair Question

Post by nintendoafterparty » Wed May 13, 2020 10:42 pm

Hi there, I'm new to these forums so apologies if this isn't the best place to ask this question, but it's been more difficult than expected to find a forum or community about NES game repair. Please feel free to point me in the right direction if there's a more suited online location.

In case you're up for helping with this game problem, what my cartridge is doing is this: powers on fine, start screen comes up and looks good. Once the team select screen appears though, there's some garbled graphics and characters toward the bottom of the screen but I can move the cursor and choose a team. Teams are chosen and game starts. Opening kickoff happens fine but when the play select screen tries to appear, total garbled graphical mess and game ceases to run past this point. This is consistent after cleaning with alcohol, deoxit, and reflowing all chip solder points. Could it be the two caps even though they look fine? Bad character ROM? If so, are there replacement chips available online somewhere for programming? I'm just getting into the world of NES repairs and know just enough to start asking questions. Once again I do apologize if this is the wrong spot to ask this and I won't bother you again, but if you could point me in the right direction that would be really great. Thanks for any info,

Blake

P.S. This website seems super awesome and makes me wish I had programming skills. Perhaps I'll start learning. I've talked about game ideas with friends for years.

lidnariq
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Re: Tecmo Super Bowl Repair Question

Post by lidnariq » Wed May 13, 2020 10:52 pm

Do you have other games? Do they work fine?

nintendoafterparty
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Re: Tecmo Super Bowl Repair Question

Post by nintendoafterparty » Wed May 13, 2020 11:07 pm

Yes I've got many other games and they've all worked flawlessly after I've cleaned them. I will say I haven't gone as far as Brasso yet as I figured Deoxit and a magic eraser would suffice. Plus the pins on TSB actually look really shiny and spot free. I did just remember I have another NES I can try it on though. Let me do that real quick.

nintendoafterparty
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Re: Tecmo Super Bowl Repair Question

Post by nintendoafterparty » Wed May 13, 2020 11:17 pm

Yep same exact result on the other NES. Completely different setup. Different system different cables different tv so blame it on the game.

lidnariq
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Re: Tecmo Super Bowl Repair Question

Post by lidnariq » Wed May 13, 2020 11:55 pm

You shouldn't need anything harsher than deoxit, really.

My best guess, based on the symptoms you're describing, is that the PRG ROM is somehow subtly damaged. You could buy a dumper like the Kazzo or INLretro dumper-programmer to see if that's true, or you could just assume it is and buy some kind of programmable memory and all of the soldering kit needed to replace it.

If this is correct, you'll need a 256KB PROM, such as the SST39SF020A or GLS27SF020, as well as a programmer.

It's also credible that the RAM is what's damaged. Hard to really say.

nintendoafterparty
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Re: Tecmo Super Bowl Repair Question

Post by nintendoafterparty » Thu May 14, 2020 7:28 pm

Excellent, thanks a lot. This is the kind of info I've been looking for. Would I need programming language skills to tell if it was subtly damaged via a dumper? I'm pretty sure I'm gonna be into this for the long haul so buying some PROMs and a programmer was something I already figured would happen, I just didn't know what to look for. I appreciate your input. Here's some newb questions I have...

I see the PRG and CHR ROMs as well as three other "chips" on this board. Is the MMC3B Is the main "processor" of sorts or is this RAM?

There's another chip sitting parallel to the ROMs. Sanyo LC3564PL. What is this?

Another chip sitting perpendicular to the CHR ROM, smaller 61113B1 branded Nintendo. What is this chip?

Say I buy some of the 256KB PROMs you mentioned, are they programmable for either CHR or PRG or is there a specific chip for each need?

Thank you so much for any info.

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tokumaru
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Re: Tecmo Super Bowl Repair Question

Post by tokumaru » Thu May 14, 2020 8:08 pm

nintendoafterparty wrote:
Thu May 14, 2020 7:28 pm
Would I need programming language skills to tell if it was subtly damaged via a dumper?
You just need a file compare utility to check for differences between your version and a known-good one, no programming skills necessary.
I see the PRG and CHR ROMs as well as three other "chips" on this board. Is the MMC3B Is the main "processor" of sorts or is this RAM?
The MMC3 is the mapper. A "bare" NES console can only take 32KB of PRG memory and 8KB of CHR memory, but as time went by those limits started to become a problem, and developers started using mappers to manage larger amounts of memory. Mappers are used to dynamically map small chunks of large memory chips into the small windows that the NES can see.
There's another chip sitting parallel to the ROMs. Sanyo LC3564PL. What is this?
This is an extra 8KB of RAM (the "64" in the name indicates a size of 64 kilobits, which equals 8 kilobytes), which complements the 2KB of work RAM that are built into the NES.
Another chip sitting perpendicular to the CHR ROM, smaller 61113B1 branded Nintendo. What is this chip?
This is the CIC - the lockout chip - which communicates with the CIC inside the console, and when both chips don't come to an agreement, the NES keeps resetting itself.
Say I buy some of the 256KB PROMs you mentioned, are they programmable for either CHR or PRG or is there a specific chip for each need?
The same kind of chip can be used for both purposes as long as it's fast enough (NES doesn't need particularly fast chips), but you may have to wire them differently when soldering them to the board. I'm not sure if you know this, but the pinouts of programmable chips are generally not directly compatible with the pinouts of Nintendo ROM chips (except for very small ones - 32KB and below), so you always need to do a bit of rewiring, rerouting some pins to the correct holes.

Using chips that can hold more data than necessary is not a problem either, as long as the chip physically fits on the board (some boards designed for 28-pin chips can't take a 32-pin chip due to the proximity between the chips, for example). You can simply connect specific pins to GND in order to force only the lower part of the chip to be used.

nintendoafterparty
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Re: Tecmo Super Bowl Repair Question

Post by nintendoafterparty » Fri May 15, 2020 12:35 am

Thanks, I'm really enjoying learning about this. I basically have zero knowledge of programmable chips but it's always been an area of interest. Couple that with Nintendo though and I think I'm finally ready to start learning. I work at a guitar pedal company so soldering is an every day task which I really enjoy. I'm not the designer or creator of the pedals though so I've never needed to understand the hows and whys of chip technology as much.

Something else I thought of - I noticed there are certain traces say, coming from the MMC that are very short and terminate to just a hole. There are other nearby traces doing the exact same thing but the hole is filled with a tiny dot of solder. Are these differences significant or could they all be blank or all filled and have the same result? I'm asking because if I'm soldering a nearby pin I want to know if I need to remove solder from those holes if a tiny bit bleeds into them.

I'm gonna start looking for a few items you've mentioned. I appreciate the info. One last question this stuff made me think of... I had another game that consistently powered on to a black screen, but would work perfectly after the reset button was pushed once. I never bothered more with it since it worked with just that one blip. Based on your explanations would this problem point to the lockout chip? Just figured I'd take a guess.

tepples
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Re: Tecmo Super Bowl Repair Question

Post by tepples » Fri May 15, 2020 6:12 am

Some traces on a printed circuit board appear to terminate but continue through a plated via, which carries the signal from one side of the board to the other.

Other traces terminate to the edge of the board or to an unplated hole drilled for mounting the case. These traces go into a margin that is cut off before assembly in order to make all traces continuous for gold electroplating the cart edge connector.

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