How to go about fixing this NES cart?

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RottenToTheGore
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How to go about fixing this NES cart?

Post by RottenToTheGore »

http://imgur.com/a/M1l2wtp

Friend showed me this cart recently that wasn't working, looks like someone tried to fix it with the 2 wires.

Would scraping a little solder mask off the traces after the break and running wires directly from the chip pins be worth trying?

Otherwise I could always just find a donor pcb but I'd rather try to salvage this.
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Sumez
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Re: How to go about fixing this NES cart?

Post by Sumez »

RottenToTheGore wrote: Would scraping a little solder mask off the traces after the break and running wires directly from the chip pins be worth trying?
Hmm, isn't that what this fix already tries to do though?
I don't know the exact wiring of a SLROM PCB, but I'm assuming the broken traces are meant to connect the legs connected by those soldered on wires.
RottenToTheGore
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Re: How to go about fixing this NES cart?

Post by RottenToTheGore »

Sumez wrote: Hmm, isn't that what this fix already tries to do though?
I don't know the exact wiring of a SLROM PCB, but I'm assuming the broken traces are meant to connect the legs connected by those soldered on wires.
That's what it looks like, but it didn't seem to work for my friend trying to play it. I don't know the wiring either so I figure I would just go directly to the trace.
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Sumez
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Re: How to go about fixing this NES cart?

Post by Sumez »

Just had a guy check on the wiring, and it looks like the traces have been run correctly in that fix.

So my guess is either the wires haven't been soldered properly (easy check with a multimeter), or more traces have been broken than immediately visible.
Or maybe it just appears to not be working because the connector is not properly cleaned like a ton of NES cartridges nowadays? :D
RottenToTheGore
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Re: How to go about fixing this NES cart?

Post by RottenToTheGore »

Sumez wrote:Just had a guy check on the wiring, and it looks like the traces have been run correctly in that fix.

So my guess is either the wires haven't been soldered properly (easy check with a multimeter), or more traces have been broken than immediately visible.
Or maybe it just appears to not be working because the connector is not properly cleaned like a ton of NES cartridges nowadays? :D
Thanks for checking! I planned on cleaning/testing continuity if I'm able to get my hands on it, good to know it could be already fixed.
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Syntax
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Re: How to go about fixing this NES cart?

Post by Syntax »

Doesn't look like its wired correctly.

I highlighted a chip leg in red, and one in yellow.

your wire goes to the yellow leg, but really that trace should look like the red leg if it went there, youd be able to see it clearly going into pin 4 but it avoids it.

https://imgur.com/a/A4G5miu
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Sumez
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Re: How to go about fixing this NES cart?

Post by Sumez »

Are you sure about that? Looks like Pin 3 on the mask rom is already connected to another pin on the MMC1. Or am I bad at deciphering the traces on the picture?

EDIT: Nevermind, I misunderstood your message. I thought you mean they needed to wire it to pin 3. Yeah it does look like it leads to one of the "lower" pins of the mask rom, similar to the other trace. Maybe I'll try to find a SLROM-06 board myself and test it out.
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Sumez
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Re: How to go about fixing this NES cart?

Post by Sumez »

Just cracked open a TMNT cart to test for myself, and I can also confirm, the traces definitely connect the way those wires do.
RottenToTheGore
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Re: How to go about fixing this NES cart?

Post by RottenToTheGore »

I've been digging around in NESCartDB and the NESDEV Wiki, and if I understand it correctly it does look like it's wired ok.

Pin 7 and 8 on the MMC1 go to CHR A12 and A13
CHR A12 is pin 4, A13 is pin 28.

Does that sound correct to anyone who knows more about this?

I asked them to mail me the cart, eventually I'll get a chance to check it out myself.
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vol.2
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Re: How to go about fixing this NES cart?

Post by vol.2 »

Edit: I found a clearer picture of the godzilla cart and I was missing something.

https://i.imgur.com/0i27FLx.jpg

I can't tell where those land, but I still think Syntax is right that one of those wires is going to the wrong place.


If you look at that image I linked, I put 2 X's on what look like the correct traces to me. If you scratch off the solder mask in those places, you can then measure continuity between those spots and the legs of the chip. The traces should be fine from those points forward, so it should map the pins correctly.
Last edited by vol.2 on Fri Apr 16, 2021 3:12 pm, edited 2 times in total.
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Sumez
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Re: How to go about fixing this NES cart?

Post by Sumez »

Take out a multimeter and an SLROM cartridge of your own (it's an incredibly common PCB, like I said, TMNT is one). The wires are correct.
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vol.2
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Re: How to go about fixing this NES cart?

Post by vol.2 »

Also, if you have a desoldering gun, you can just remove the chip and see where the traces go visually without scratching off the solder mask. If you do end up scratching the mask off, you can use some clear nail polish to cover it over when you are done.
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Syntax
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Re: How to go about fixing this NES cart?

Post by Syntax »

The trace must wrap around back to pin 4 then, looks like it avoids it from the pictures.

Just remove those wires and repair the traces and see if it works I say.
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