I have a weird (to me at least) firepower scoring or switch problem which I think is under the playfield. I need some basic troubleshooting help such as what is the difference between a row problem and a column problem. I put a new rottendog MPU 327 and played for a while and all was fine. I then started having a switch column problem which I spoke to Jim at rottendog about and just got a replacement board which is installed. Because of that I think the problem is under the playfield. here are the details:
1) The #6 arrow blinks but when it is hit, you get a sound,but it does not score and the light still blinks
2) All other switches on the same column behave the same way
Here is what I did:
I checked all diodes (in circuit) in the column and each tested within the proper voltages on the band side and null on the other side except the spinner. The spinner tested fine on the band side but was not null on the otherside. I cut one side and tested out of circuit and it then tested null. I went ahead and replaced the diode but still have the same problem.
Am I missing something basic? Remember that I think it must be under the playfield since I have the same problem with two boards.