[Article 6270]Omega Race (2) :: PCB – part 3

Here the problems I had yesterday.

  1. BBU RAM S4: BAD
  2. V RAM2 J1 and or (L/M)1: BAD
  3. V RAM4 (J/K)1 and/or (N/P)1: BAD
  4. V ROM2 F1: BAD

 

1 – It was related to a power problem. I can’t understand connecting the oscilloscope ground to the game ground the probe wire becomes hot. Anyway problem solved.

 

 

2 – V RAM2: This was the most complex error. The analysis made yesterday had no success but considering now the problem was related to J1 and or (L/M)1 only I pointed my attention to the “Chip enable” circuit. After some tests I could see I forgot to rebuild the track between 7404 in position PR1 PIN 8 to 7432 in position R1 pin 10.

omegarace2_troubleshooting

3 – V RAM4: (J/K)1 2114 was faulty. I just replaced it.

 

4 – V ROM2 F1: ROM was actually bad and I replaced it with a new one.

 

This is the self-test result. I’m sorry I didn’t manage Z signal 😀 😀 😀

omegarace_1321

so, PCB now is ok…

 

What have I to do now?

  • No sound to the right speaker
  • Monitor (not working)
  • Back panel