Recently purchased this original pow pcb from a member as faulty ,description of the fault was no picture and sound issue.
Here it is on my repair bench.
ok now lets plug in the harness and fire it up..........
ok so the good news is it boots and the game runs but nothing can be seen apart from the left of the screen where you can see some tile gfx.
i can coin up and i can hear the sound but strangley only the samples but no music?
When booting up i got the message LSPRITE error so it looked to me this good be a addressing issue or possibly bad graphics roms.
All the data for the tiles and sprite roms are located on the sub board,i removed all eproms and did a romident,all passed ok.
Looking at the pcb i noticed a bank of 3 srams (6264) which i think is the VRAM,while the game was running i shorted out some address pins and i could see parts of the tiles on the left of the screen change.
So it looks like i am on the right track
,started scoping all the address pins which were active except pin 21 (A0) which was low?
Followed this pin21 to a ls157 pin 7.
Pin 7 is the output pin ,checked pin 5+6 inputs on the scope and they looked ok,decided to remove this for a new ls157.
Ok now its fitted,lets fire it up.........
cooool it worked,all graphics back and all controls working.
Last fault remaining is to find the lost music,i will be back to finish this repair.
Here it is on my repair bench.
ok now lets plug in the harness and fire it up..........
ok so the good news is it boots and the game runs but nothing can be seen apart from the left of the screen where you can see some tile gfx.
i can coin up and i can hear the sound but strangley only the samples but no music?
When booting up i got the message LSPRITE error so it looked to me this good be a addressing issue or possibly bad graphics roms.
All the data for the tiles and sprite roms are located on the sub board,i removed all eproms and did a romident,all passed ok.
Looking at the pcb i noticed a bank of 3 srams (6264) which i think is the VRAM,while the game was running i shorted out some address pins and i could see parts of the tiles on the left of the screen change.
So it looks like i am on the right track
,started scoping all the address pins which were active except pin 21 (A0) which was low?Followed this pin21 to a ls157 pin 7.
Pin 7 is the output pin ,checked pin 5+6 inputs on the scope and they looked ok,decided to remove this for a new ls157.
Ok now its fitted,lets fire it up.........
cooool it worked
,all graphics back and all controls working.Last fault remaining is to find the lost music,i will be back to finish this repair.
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