Sly Spy with corrupt graphics

S

Spirantho

Newbie
Credits
22CR
Hi everybody,

I've been playing with repairing my Sly Spy PCB today.

It has a graphical error, which isn't unusual... but I'm not sure what's causing it.

It's the tiles that are wrong, and they're on FA08 and FA09. I've checked the EPROMs and they're fine.

The next thing I did was check the address lines by making ROMs which have a line held high and running them in MAME - but the start "don't use drugs" screen obviously isn't just held in memory as this didn't replicate the screen.

So I'm left thinking that the tile map is being rendered correctly inside a graphics chip, but is leaving the chip wrongly - probably a bad address line, as quite obviously the tiles are being duplicated from one half of the screen to the other.

Does anyone have any ideas which may help? I know it's not a very valuable or sought-after game, but I like things like this to be working, and it's all good experience.

Thanks!

SlySpy.jpg
 
S

Spirantho

Newbie
Credits
22CR
My cunning plan worked (cough). As soon as I posted this, I found a short circuit from one chip to the other!

It's working perfectly now! Honestly, I spent hours looking at this and saw nothing, and within seconds of posting this it was fixed.

Please ignore me :)
 
S

Spirantho

Newbie
Credits
22CR
That's my third fix now - not done any for a while. This was the simplest (bending a pin :) ).

Green Beret bootleg - check. Combatribes - check. Combatribes again (input buffer chip died while playing so I couldn't restart the game earlier today!) - check. Sly Spy - check.

Next up is Mug Smashers and another board I'm not sure about.....!
 
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