Recently picked this up from Positive Logic on here. It came exactly as described, partially working but with some issues. This thread is to document the fixes.
Symptom:
Line through Invaders some of the invaders.
Fix:
Reseat two PCB boards. Was advised by Andy Welburn and Rob Hassell that this was likely a problem with the 'Shifter' circuit. Luckily the reseat fixed it.
Symptom:
Game roms seems to have issues, after starting a game the invaders come straight down and land. Game doesn’t have Taito roms, instead is has Zenitone-Microsec ones
Fix:
Replace eproms with newly burned ones. This might have also had something to do with the issue repaired with the PCB reseat, no way to be certain.
Symptom:
On game start the laser base moves to the right on it’s own
Fix:
Replace 74153 @ 18
Symptom:
Missile Shot sound is high pitch whine. Base Hit sounds also missing
Fix:
Both these sounds share a common input from the ‘Noise’ circuit. Replaced 4006 @ 25, still not fully fixed so also replaced 4070 @ 26.
Symptom:
Saucer hit sound missing
Fix:
Replace 3900 @ 34
Symptom:
Pop/click sounds when pressing some control buttons during game play.
Fix:
Run new ground wire from PSU to Control panel. It still occasionally occurs but far less frequently than before, certainly it's now rare enough to live with. Andy Welburn told me this is a known issue with Taito L shaped sets using a Switch mode power supply. Strangely it doesn't affect Midway L shaped sets or happen using the original linear power supply.
Hope it's useful info to someone else down the line. Thanks again to Andy and Rob for the tips. Also thanks to Dave Langley for the cleaned up schematics!
Dan
DanP2020-11-01 16:58:59
Symptom:
Line through Invaders some of the invaders.
Fix:
Reseat two PCB boards. Was advised by Andy Welburn and Rob Hassell that this was likely a problem with the 'Shifter' circuit. Luckily the reseat fixed it.
Symptom:
Game roms seems to have issues, after starting a game the invaders come straight down and land. Game doesn’t have Taito roms, instead is has Zenitone-Microsec ones
Fix:
Replace eproms with newly burned ones. This might have also had something to do with the issue repaired with the PCB reseat, no way to be certain.
Symptom:
On game start the laser base moves to the right on it’s own
Fix:
Replace 74153 @ 18
Symptom:
Missile Shot sound is high pitch whine. Base Hit sounds also missing
Fix:
Both these sounds share a common input from the ‘Noise’ circuit. Replaced 4006 @ 25, still not fully fixed so also replaced 4070 @ 26.
Symptom:
Saucer hit sound missing
Fix:
Replace 3900 @ 34
Symptom:
Pop/click sounds when pressing some control buttons during game play.
Fix:
Run new ground wire from PSU to Control panel. It still occasionally occurs but far less frequently than before, certainly it's now rare enough to live with. Andy Welburn told me this is a known issue with Taito L shaped sets using a Switch mode power supply. Strangely it doesn't affect Midway L shaped sets or happen using the original linear power supply.
Hope it's useful info to someone else down the line. Thanks again to Andy and Rob for the tips. Also thanks to Dave Langley for the cleaned up schematics!
Dan
DanP2020-11-01 16:58:59
