Wednesday, March 10, 2021

Super Pac-Man Board Repair Log

Had a box of Super Pac-man boards sitting for years (some tagged as being checked in 2002), also had some free time to go through and get them running.  One of the easiest boardsets to work on, in my opinion, most of the crucial ICs are socketed (customs, processors, roms and most ram).  So chip swapping can solve a lot of problems.  Luckily it seems most of the Namco customs on these boards don't suffer from oxidation, at least not many in this pile.  Here's the recap:

Repair Procedure

  1. Narrow down to video or CPU board first, having a working set makes things very easier in this case.
  2. Most of the important ICs are socketed, swap between to find bad one.
  3. Use Self-test to assist, checks most rom and rams.

CPU Boards

Rom 3 Error (3/11/21)

  1. Immediately noticed a blob of solder near the input connector, didn’t appear to be shorting anything out, but took it as a sign.
  2. Sure enough found another blob of solder next to rom 1K (Rom 3), figured this was a simple repair. Removed the solder and board works, right?
  3. Wrong, removed the solder still got rom 3 error. Swapped Rom 3, processor at 1L, 1M and 1N, not change.
  4. Really puzzled now, pulled socket shells to look for extra solder, no sign of it.
  5. Finally moved on and removed 15XX custom at 3N, board passed self-test this time, but no sound.
  6. Put 3N back in socket and board works.

Vertical lines and Vertical garbage (3/11/21)

  1. Started swapping ICs into known working board, first one, custom 07XX at 1N was bad.

Blank screen, dead (3/10/21)

  1. Bad 6809 processor at 1A

Video Boards

Blue Screen, plays blind  (3/10/21)

  1. Checked socketed, ICs, no change, but found that 3C and 3D when removed produced similar issue. 
  2. Using logic probe worked my way forward and found dead outputs at 74LS298 at 4L. Replaced 4L to fix the problem.

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