Mar 252016

Some days ago I had on the bench this Bad Dudes PCB for a repair:


Board played fine but  clearly had color palette troubles which I narrowed in CPU board by swapped a good one:


Putting my fingers on board some colors were changing so I could locate the palette RAMs in three TMM2018 chips:


Probing the chips I found that pin 6 (address line A2 in common) of all of them was completely silent, this was confirmed also by my scope:


According schematics this signal should come from pin 9 of a near 74LS157 @15H :

TMM2018@15K_address line_2

but I couldn’t measure any continuity with my multimeter.A closer inspection revealed some corrosion on pin 6 of the TMM2018 @IC78 :


I removed the chip and found that the pad was completely corroded and lost contact with its traces:


I promptly patched them and this fixed the game completely:


 Posted by at 11:21 pm

  One Response to “Bad Dudes Vs. DragonNinja repair log”

  1. Nice!! Thanks man!

Sorry, the comment form is closed at this time.