Irem M92 board - glitched sprites.

[yoganuggy]

I've an irem m92 board with glitches sprites.

All eproms are good dumps.

Usually I'd shotgun all the ram but the ram test at boot time passes. Should I do it anyway? Would anyone know what ram or ttl are involved in sprite generation (there is no schematic for m92).


Thank you!

 

[sukhbir]

Possibly lifted legs of the custom sprite chips .

 

[Ace`]

If the little jumper isn't missing or on the wrong pins then you most likely have a bad GA22 custom chip, very common failure.

 

[G-man]

Had the same on an Irem board (not sure it was m92 though), it was the jumpers that were incorrect.

 

[yoganuggy]

Do you mean the j3 jumper on the main board? That's in place (if I take that jumlper off the sprites disappear completely).

If it's the custom then this is toast. M92 boards on ebay are ludicrously expensive.

 

[sukhbir]

These customs puts the end of the repair,RIP 😫

 

[ExZX]

If the GA22 custom is burning hot then it's toast. Parts board

 

[Monstermug]

Apply pressure to it with your finger, quite firmly and if graphics doesnt change then its probably that. If it changes it may just need a reflow.