Mar 292020
Got two Pacland pcbs to be repaired from a friend.
Fist one is a Sidam Pacland which showed the following problem:
All the screen had shadowed colours going up and down vertically.
By expecience whith similar problems on different hardware I understood it was a Hblank problem.
The game didn’t shut off the screen at the borders so the monitor didn’t have anymore the black reference.
Looking at the schematics I found immediately a clear reference to the blanking circuit:
Compblank was oscillating, while COMPBLANK A and \COMPBLANK A were stuck.
Chaning the 74LS74@6M fixed completely the issue
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