Black Tiger repair log #2

 PCB Repair Logs  Comments Off on Black Tiger repair log #2
Apr 142018
 

Got a Black Tiger for a repair which had a colour problem on some graphics

It lacked some shades of colour

I decided to look around the palette rams @6C and 6D until I found a fixed address line

Tracing back I found an 74ls157 @5D with an output stuck low.

After checking the inputs I found one of them stuck low and according to its truth table, the output is always low.

Tracing back I found a 74ls273 witth Q3 output low and D3 input oscillating.

Piggybacking a good one restored the correct colours.

After changing it , the game was completely fixed

 

Black Tiger repair log #1

 General, PCB Repair Logs, Repair Logs  Comments Off on Black Tiger repair log #1
May 052017
 

A friend of mine sent this pcb to check why the background was all messed up

I immediately noticed¬† in demo mode that all the characters fell down in an endless loop because they couldn’t walk on the platforms

After searching for the fault in the video board for some days, I decided to test all roms starting from the program ones.

Program rom 04 didn’t match with anything in Mame and after checking the pattern I saw it was full of garbage.

 

After reprogramming with a good dump, the game was restored perfectly.

It seems rom 04 has only the layout of all levels because even without its presence the game is booting