Konami System GX Boot Loop Problem

[lukemorse1]

This one is a bit puzzling.

I have a Konami System GX board that was laying in the repair pile but I had no idea what was wrong with it. After power up without a rom board I noticed that it was just static garbage and resetting. I tracked that problem down to the motorola cpu and replaced it. After that, the system would go through its "Warning, sub board not attached..." error like it should.
I have since connected 2 different sub boards to the motherboard and tired to boot a game but no matter whichever board I use, the system does a continuous boot loop. EEprom Initialize works fine, all roms come up as "OK" but nothing will start up, just keeps resetting.

Anyone else experience anything like this before?

I have tried reburning a different 34K bios , going over the pins on the konami custom qfp, trying to reflow the ram chips. visually inspected all pins on both boards and looked for trace damage but all is fine, checked for 5v on the board and still the same. Really not sure what else could cause it not to fire up.
Both Sub boards are also working fine on a different GX motherboard.

Pictures below.

 

[ic3b4ll]

IIRC, there's some buffers between both boards. 74LS245 maybe?
But I also remember I had to abort fixing a motherboard because the BIOS ROM is connected to a pair of customs and one was dead. They are easy to spot, because, erm, there's two of them. I bet one of them is really hot, i.e. shorted. I believe they control the data or address bus for the main CPU, enabling the BIOS or program ROM.

 

[lukemorse1]

IIRC, there's some buffers between both boards. 74LS245 maybe?
But I also remember I had to abort fixing a motherboard because the BIOS ROM is connected to a pair of customs and one was dead. They are easy to spot, because, erm, there's two of them. I bet one of them is really hot, i.e. shorted. I believe they control the data or address bus for the main CPU, enabling the BIOS or program ROM.

Interesting info there. Ill have to go back and check and see if one gets hot or not. Ive put this one back in the parts pile for now but you might be on to something there.
These konami customs have become a nightmare with a few of the boards Ive replaced them on recently. Hopefully Furrtek will be able to reverse engineer a coupe of them soon. I know he has been working on one or two.
Thanks again.