I'm currently repairing a friend's ST-V. I fixed the CPUs (which there were visible cracks on solders) fixed the damaged pins of 315-5778 IC and 315-5688 IC and lastly put a spare terminator PCB for the missing one.
The board boot to an "Error on cartridge" error which is expected without a game cart. Continue with service button, it hangs at "System checking" screen. On the test menu, RAM check reveals IC37 BAD. I knew from a previous repair that this error does not necessarily an indication of the bad sound RAM (IC37) but rather it is caused by a faulty GAL
I burned a new GAL from jammarcade.net and fixed the "IC37 BAD" error. Now the board "seems" fully working with sound and everything. On the factory test menu I checked the Dual-cpu and it shows GOOD. Sound tests OK and there is sound, all RAM tests OK (However the CRT and VDP tests does not work with the burned GAL but this is not specific to this PCB. Puyo puyo sun does not work with that dumped GAL either, anyway that is a another topic)
So where is the problem you may ask...
This PCB does not recognize my Tecmo World Cup 98 carts (Carts confirmed working on my other working ST-Vs). However, other carts either work (i.e. Columns 97) or at least recognized (i.e. Die Hard throws a region error - normal).
One thing I noticed different on this ST-V is that it has a small daughter board attached on top of IO connectors and a missing terminator PCB. I searched it on Google and findout that this might be an indication of this ST-V might be coming from a print club cabinet (not 100% sure though). I don't know this is relevant with my problem but is there anything special about these print club PCBs that they wont recognize certain carts?
I also tried the modbios v1.11 but same. It just don't recognize the cart (way before the region selection information menu). I also tested with an original (sega part number on it) known working GAL. Still same...
Any suggestions in where else to look at?
The board boot to an "Error on cartridge" error which is expected without a game cart. Continue with service button, it hangs at "System checking" screen. On the test menu, RAM check reveals IC37 BAD. I knew from a previous repair that this error does not necessarily an indication of the bad sound RAM (IC37) but rather it is caused by a faulty GAL
I burned a new GAL from jammarcade.net and fixed the "IC37 BAD" error. Now the board "seems" fully working with sound and everything. On the factory test menu I checked the Dual-cpu and it shows GOOD. Sound tests OK and there is sound, all RAM tests OK (However the CRT and VDP tests does not work with the burned GAL but this is not specific to this PCB. Puyo puyo sun does not work with that dumped GAL either, anyway that is a another topic)
So where is the problem you may ask...
This PCB does not recognize my Tecmo World Cup 98 carts (Carts confirmed working on my other working ST-Vs). However, other carts either work (i.e. Columns 97) or at least recognized (i.e. Die Hard throws a region error - normal).
One thing I noticed different on this ST-V is that it has a small daughter board attached on top of IO connectors and a missing terminator PCB. I searched it on Google and findout that this might be an indication of this ST-V might be coming from a print club cabinet (not 100% sure though). I don't know this is relevant with my problem but is there anything special about these print club PCBs that they wont recognize certain carts?
I also tried the modbios v1.11 but same. It just don't recognize the cart (way before the region selection information menu). I also tested with an original (sega part number on it) known working GAL. Still same...
Any suggestions in where else to look at?
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