Another one:
Board booted but graphics were all messed up.
Decided to rig the PCB up to the Fluke. ROMs 6E to 6J were reading fine but there were problems with 5E and 5F.
This is testing ROM 5E - signature 0-FFFF-E576.
Error message
Started to look at the schematics and traced a bad line from pin 7 of 5E and 5F all the way back to 1F a 74ls283 with pin 1 stuck output high.
Removed and replaced the 74ls283 at 1F and it brought back all the text but there were still slight issues with the sprites
Started looking at the sprite RAM 2A to 2D and found pin 4 of 2A and 2B were floating. Removed previously installed sockets and discovered two minute broken traces under the sockets.
Patched in two repair lines and game is cured.
jonhughes2018-03-22 12:29:25
Board booted but graphics were all messed up.
Decided to rig the PCB up to the Fluke. ROMs 6E to 6J were reading fine but there were problems with 5E and 5F.
This is testing ROM 5E - signature 0-FFFF-E576.
Error message
Started to look at the schematics and traced a bad line from pin 7 of 5E and 5F all the way back to 1F a 74ls283 with pin 1 stuck output high.
Removed and replaced the 74ls283 at 1F and it brought back all the text but there were still slight issues with the sprites
Started looking at the sprite RAM 2A to 2D and found pin 4 of 2A and 2B were floating. Removed previously installed sockets and discovered two minute broken traces under the sockets.
Patched in two repair lines and game is cured.
jonhughes2018-03-22 12:29:25
