Got this original Konami Vendetta PCB from a batch of faulty boards I recently bought:
Board was really brand new as it was come out from the factory but once powered on I was greeted by a flashing white screen sign that the watchdog circuit was active and the board kept to resetting:
Usually the watchdog is on because there is some troubles in the main code execution.So I started with my multimeter the check the main CPU (a custom marked ‘053248’) area and found an high resistance between ‘D1’ (DATA LINE 1) of the CPU and the program ROM:
Obviously, for the proper CPU operation, all its address and data line must be daisy chained with the main code ROM as confirmed also by schematics:
So I used a provisional patch wire and board booted fine:
But external appearance matters too.So, following the path of this data line, I found the point where the track was interrupted (picture on the right was taken with USB microscope) and I patched it with some AWG30 wire:
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