Game board does not work, mostly blue screen with
some random dots
- Noticed bi-polar PROM was missing, replaced with my bi-polar PROM solution
- Now I get a bunch of equally space boxes on the screen
- Did long Fluke RAM tests
- 0x0003 - 0x0BFF working RAM (dynamic) 4416s - Bad, changing values while reading in looping mode
- 0x0c00 - 0x7FFF screen RAM (dynamic) 4416s - bad
- 0x8000 - 0x8dff - working RAM (static) 6116s - OK
- 0x8000 - 0x8eff - motion object buf 2 - OK
- 0x8f00 - 0x8fff - motion object buf 1 - OK
- Noticed that the 4416 @ 4E was burning hot to the touch, replaced
- Now I'm getting BTS 0x0f errors doing RAM test of 0x0003 - 0x0BFF, BTS 0x0F @ 0x000F
- Replaced 4416 @ 4f which is the low bits of "odd" addresses in the range 0x0003 - 0x0BFF , now ram test makes it past address 0x0003 to fail at BTS 0xFF at 0x0004
- "even addresses" in the range 0x0003 - 0x0BFF are provided by 4416 RAMS @ 4H (low 4 bit) and 4J (high 4 bits)
- replaced 4H and noticed that now I have errors 0xF0 @ 0x0004, which is expected as the chip that provides the low 4 bits was just replaced.
- Replaced 4J and now RAM test for 0x0003 - 0xBFFF and 0xC00 - 0x7FFF pass OK!
- Game is now booting, but missing lines in sprites
- Noted that 2149 @ 10A is also burning to the touch, replaced
- Lines in sprites gone, but there is an overwhelming blue color to the game
- Pushed down on 7404 @ 11P, noticed the colors become correct, noted someone had replaced 7404 and it looked like the solder job wasn't complete on one of the vias, resoldered.
- Game works!