Had some time on my hands today and started looking at the fault where intermittently colours of sprites and
Corruption occur.Started looking on the rom board (bottom) where the custom pcb is fitted which, in the original board there's a 42 pin custom chip is installed and this chip generates the sprites.
Looking at the schematics pin 31-40 squirts out the sprite data.
As I started to probe the pins the corrupted colours and graphics returned back to normal,pulled the board out and inspected the header pins ,looking closely I found dry joints which were not looking great so I reflowed all pins.reffitted the board back and everything started to look ok 😀.
Lastly the weird green pixels appearing on sprites and background graphics. Looked into the colour mixing circuit checking lots of logic chips but couldn't find anything suspicious until I noticed that the 3 x 2114 colour srams were replaced before as I can see underneath of fresh solder.
Looking at the schematics the srams are supposed to be 2148 type which are faster usually 55ns,the ones fitted are 200ns.
Fitted 3 sockets and installed 3x2148 srams,powered on and left the game on test for an hour and....
Game Fixed,rygar lives to fight another day.
Corruption occur.Started looking on the rom board (bottom) where the custom pcb is fitted which, in the original board there's a 42 pin custom chip is installed and this chip generates the sprites.
Looking at the schematics pin 31-40 squirts out the sprite data.
As I started to probe the pins the corrupted colours and graphics returned back to normal,pulled the board out and inspected the header pins ,looking closely I found dry joints which were not looking great so I reflowed all pins.reffitted the board back and everything started to look ok 😀.
Lastly the weird green pixels appearing on sprites and background graphics. Looked into the colour mixing circuit checking lots of logic chips but couldn't find anything suspicious until I noticed that the 3 x 2114 colour srams were replaced before as I can see underneath of fresh solder.
Looking at the schematics the srams are supposed to be 2148 type which are faster usually 55ns,the ones fitted are 200ns.
Fitted 3 sockets and installed 3x2148 srams,powered on and left the game on test for an hour and....
Game Fixed,rygar lives to fight another day.
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