Tailsnic Retroworks
Professional
Hi. I'm trying to fix an original Joe & Mac Returns board using the mexican bootleg.
The issue I have is not booting, but the signal I have using logic probe on 27C4002 main code A17 entry is logic 0 with alternating PULSE led, while the correct working value is constant PULSE.
I have checked backwards and the problem comes from a 374N (I have tested it and it works). Also I have replaced the custom 156 for another working one and still fails. The bad signal comes from the VX00 GAL, but it is also working good.
For that reason, I'm searching for the schematics of this board because I don't know what is going on. Somebody can help me?
The issue I have is not booting, but the signal I have using logic probe on 27C4002 main code A17 entry is logic 0 with alternating PULSE led, while the correct working value is constant PULSE.
I have checked backwards and the problem comes from a 374N (I have tested it and it works). Also I have replaced the custom 156 for another working one and still fails. The bad signal comes from the VX00 GAL, but it is also working good.
For that reason, I'm searching for the schematics of this board because I don't know what is going on. Somebody can help me?