Problematic SNES PCB

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Fisher
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Problematic SNES PCB

Post by Fisher » Mon Nov 30, 2020 3:50 pm

A while ago I received an SNES game that didn't work.
It was dirty cheap, the only condiction the vendor asked me was that he wished to know what game it is (or was), because he told me that this game never worked, even once.
Here are some pictures of the PCB, p0rn included:
Assembled
Assembled
Solder side
Solder side
Component side
Component side
So far so good, after I received the game, the first thing I did was to dump it's ROM, a 4Mb one, and tried it on an emulator to found it was World Soccer, CRC32=a3096a8e.
I knew this game as Striker back on the day, but probably it's just another version of it.

Cool, I owe nothing more to the seller, so I tried the ROM on another board.
The game booted, but without sound and crashed on the title screen.
So, I looked at the PAL chip, and got very confused:

Code: Select all

World Soccer PAL 16L8 
           _  _
/RESET --1| \/ |20-- VCC
   A12 --2|    |19-- RAM /CE
   A13 --3|    |18-- ROM0 /CE
   A14 --4|    |17-- ROM1 /CE
   A15 --5|    |16-- /CART
   BA0 --6|    |15-- BA7
   BA1 --7|    |14-- BA6
   BA2 --8|    |13-- BA5
   BA3 --9|    |12-- NC
   GND--10|____|11-- BA4
   
I also took a look at the battery backup circuit:

Code: Select all

World Soccer Battery Circuit
                            D1
                      VCC--->|----+
         D2    R4                 |
    +---->|---/\/\---+------------+---->SRAM VCC 
    |          1K    |            |
   ---             C4| +          |
    -               === 22uf      /
   ---               |         R5 \ 
    -                |            / 33K
    +----------------+            \
    |                |            |
   GND               \            | 
                  R3 / 100K       +----> SRAM /CS
                     \            |
                     /          C B E Q1 2SC1815
                     |    R2    |   |
            /RESET---+---/\/\---+   |
                     |   100K       |
                  D3 V              |
                     -         C2   |
                     +---------||---+
                     |   R1    10   |  
                     +--/\/\--------+---> PAL RAM /CS
                     |  33K
                     +----------> VCC
Please, feel free to correct any erros/inconsistencies whithim these draws.

So, as the game never worked, I suspected of a broken PAL IC so, how oftem these get damaged?
I tested the SRAM and it's defective. Since this game booted without SRAM, would a problem there make difference or it depends?
The emulator also says it's a LoROM game, is the A15 pin is only used to decode SRAM?
As a guy who doesn't like soccer much, wich PCB should this one is equivalent, just in case I decide to do a repro of it?

Thanks in advance.

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poorstudenthobbyist
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Re: Problematic SNES PCB

Post by poorstudenthobbyist » Mon Nov 30, 2020 4:21 pm

https://snescentral.com/article.php?id=0866

Looks like this game didn't originally use SRAM in the first place?

I'd be interested to know more about that mystery chip though.
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lidnariq
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Location: Seattle

Re: Problematic SNES PCB

Post by lidnariq » Mon Nov 30, 2020 4:28 pm

Fisher wrote:
Mon Nov 30, 2020 3:50 pm
I tested the SRAM and it's defective. Since this game booted without SRAM, would a problem there make difference or it depends?
Depends on just how defective. The RAM could have been fighting with other things so that nothing could successfully drive the data bus.
The emulator also says it's a LoROM game, is the A15 pin is only used to decode SRAM?
That's the normal LoROM map, yes. For games this tiny - only 512KB - sometimes A15 wasn't even a factor. (e.g. 1A1B)
As a guy who doesn't like soccer much, wich PCB should this one is equivalent, just in case I decide to do a repro of it?
Striker is on 1A0N; it shouldn't have cared about any RAM on the board.

This PCB appears to be general enough that you could fit any LoROM game with up to 2x1MB of ROM and 32KB of RAM, all just depending on the PAL.

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Fisher
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Re: Problematic SNES PCB

Post by Fisher » Tue Dec 01, 2020 7:29 am

poorstudenthobbyist wrote:
Mon Nov 30, 2020 4:21 pm
https://snescentral.com/article.php?id=0866

Looks like this game didn't originally use SRAM in the first place?
Looks like the pirates also become confused sometimes. lol
poorstudenthobbyist wrote:
Mon Nov 30, 2020 4:21 pm
I'd be interested to know more about that mystery chip though.
If you mean the PAL chip, I think I can "dump" it as a ROM, but I'll need help to figure out its equations.
But if you mean the CIC clone, I have no idea how to start.
If someone can give me the directions, I'll sure try to follow it.
lidnariq wrote:
Mon Nov 30, 2020 4:28 pm
Depends on just how defective. The RAM could have been fighting with other things so that nothing could successfully drive the data bus.
Correct!
Recently I fixed a Super Mario Allstars + Super Mario World that at first I thought was a problem with the demux, but in fact, it was a bad SRAM that wasn't allowing it to boot.
lidnariq wrote:
Mon Nov 30, 2020 4:28 pm
That's the normal LoROM map, yes. For games this tiny - only 512KB - sometimes A15 wasn't even a factor. (e.g. 1A1B)
Seems pretty flexible! :-)
lidnariq wrote:
Mon Nov 30, 2020 4:28 pm
Striker is on 1A0N; it shouldn't have cared about any RAM on the board.
I'll take a good look at my test board, probably it's having some problems.
I'll look if the emulator creates some SRAM file too.
Looks like this game has at least 4 different versions, not sure if any of them has the save function.
Probably that's just a game on the wrong board.

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Fisher
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Re: Problematic SNES PCB

Post by Fisher » Tue Dec 01, 2020 12:59 pm

Well, I think I've discovered some stranger things.
At the options screen, there's a command to "Reset Battery Backup":
Teste_00000.png
Teste_00000.png (30.27 KiB) Viewed 3037 times
The emulator also seems to initalise the SRM file:
Captura de tela de 2020-12-01 165414.png
Captura de tela de 2020-12-01 165414.png (5.47 KiB) Viewed 3037 times
Captura de tela de 2020-12-01 165444.png
Does anyone have the original version of this game that can share some pictures?
I think this one is the japanese version.

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Fisher
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Re: Problematic SNES PCB

Post by Fisher » Wed Dec 02, 2020 9:46 am

According to SuperFamicom.org only the Japanese version of this game has battery backup, wich is odd.

I also tried to "dump" the PAL chip, but the file I've got is only FFs. I'll check the circuit with more time and try again.
If I keep getting FFs does it means that the PAL chip is blank or defective?

lidnariq
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Re: Problematic SNES PCB

Post by lidnariq » Wed Dec 02, 2020 12:31 pm

Blank, defective, or locked.

That said, given how it's wired, it'd be straightforward to come up with a new fusemap for it.

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