Golden Axe Repair Log

Fixed a PCB? Tell us how!
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Runik
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Golden Axe Repair Log

Post by Runik »

Hi there !

Got some problem with a System16 Shinobi board some time ago, I thought it might be a good idea to share the way I fixed it ... it's not a hardcore repair log like Womble or others do, it's more like a "common sense" fix :P
It was also my first repair :)

So the title screen got "SEGA", "press start" and "freeplay" markings garbled

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Strangely enough, parts of the attract mode were ok ...

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... while other parts where garbled

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On the last pic, the start of the sequence is perfect, but degrades gradually as the scrolling goes ...

I ran the self test, all the roms where good, so the problem comes from elsewhere.

Using Mame sourcecode, I ran through the documentation for this game, and started to remove some roms from their sockets in order to isolate the problem. After running the self test again, all the roms were still good (even those that were removed :shock: )
So from now on I didn't trust the self test for this board anymore :P

Luckily enough, I had a second Golden Axe board handy, so I swapped all the roms between the boards. Guess what ? The problem was still there.
So I swapped the PLA (programmable logic array) from the known good board, and everything was back to normal :)
It's the red circled IC in the next pic

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Before ordering a replacement part on internet, I cleaned the pins using surgical spirit, and used thin sandpaper to remove oxidation ... and voilà ! The board is as good as new :)

I hope it wasn't too hard to understand, as I'm not used to do technical posts in english, and remarks are welcome :)
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davewellington
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Re: Golden Axe Repair Log

Post by davewellington »

Thank you very much for your post :)
all your wiki pages belong to me
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opt2not
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Re: Golden Axe Repair Log

Post by opt2not »

Nicely done, and thanks for sharing your findings with us.
firebird
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Re: Golden Axe Repair Log

Post by firebird »

Hello!

I have a problem with my Golden Axe board. It starts up just fine, I can add credits and start the game. But after killing the fourth bad guy the picture "hangs". Sound continues to play, but the picture is dead still, no response when moving stick or pushing buttons. This always happens at the fourth bad guy killed, but in some rare cases it doesn't happen and I can play further. I checked the voltage and adjusted it from about 4.9 til 5.04 VDC, but the problem persists.

Too me this sounds like a "logic/rom problem" rather than a bad capacitor or other mechanical damage. What do you think?

Here is a picture of the board:
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Best regards
Firebird
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leonardoliveira
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Re: Golden Axe Repair Log

Post by leonardoliveira »

Just being informative, the usual function for PLA, PAL and such devices on ROM boards are usually allow for the game developer an mean to change how the ROM sockets are mapped within the machine memory map. It's better than jumpers because it also happen to function as a mechanism to discourage bootlegging. :awe:

And the way the OP board glitched sure looked like addressing error on graphic ROMs. This insight might help someone trying to diagnose graphic faults on boards. The dirt/oxidization reported by the OP had the exact same problem as a broken trace, which would let inputs floating, causing errors to the data being output from the afflicted ROM bank. Should that be on the program ROMs the processor would not be able to start or would be working in a very precarious manner. :roll:
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