I have an Apollo 13 machine. I've repaired several things over the years. The battery holder was a bit corroded and the memory would be wiped if I turned it off and back on. Based on recommendations, I replaced the battery holder and got it away from the circuit board. To do this, I unhooked the several connectors from the control board, removed it and soldered a new battery pack with a length of wires to the board. I replaced it, re-seated all the connectors, and turned the machine back on. Here is where my multiple problems started.
The machine would boot and get to the point where is was looking for input for "Novice" or "Regular" and get stuck there. I know the flipper switches were working fine as when I went into the diagnostics, I tested those switches. I proceeded to pull and re-seat all of the connectors on the control board as I'm sure these haven't been pulled in a decade or longer. I was thinking there might be an issue with the ribbon cable between the control board and the I/O board. After doing this, the machine came up and everything started working flawlessly.
However, during the first game, my son saw smoke coming from the play field. We turned it off and pulled the AC power. I lifted the play field and the coil for the left turbo bumper was fried and really hot. I ordered a new coil and a new 20 pin ribbon cable for between the control board and I/O board. Foolishly, I replaced both and turned the machine back on before really getting to the root cause of the problem. I turned the machine back on. It booted and I could start the game, but none of the coils fired. A ball didn't come up to be sent up the shoot. I then went into the diag menu and tried to test the coils and nothing happened. I then smelled something burning...I fried the same coil on the left turbo bumper.
None of the fuses appeared to blow. F6 had a bit of a dark spot. I pulled it out and it had a bit high resistance, about 200 Ohms. I didn't have my manual with me or access to the internet as the machine is at a lake house. So, looking for ideas on what to do next.
Why did none of the coils work? Looks like drive transistor is Q9. I suppose I should test that, but why did none of the coils work.
One more detail. I put the new ribbon connector on and I'm not sure it was right. The end connectors on the cable were attached a bit differently than the original...I'm somewhat concerned the pins were reversed. Anyone know where I can order one more like the original.
When the machine was on and fried the coil the second time, I was back to the original ribbon connector.
How can I systematically troubleshoot this? I'm certainly not a pinball expert, but understand electronics pretty well...even though I'm more of a digital guy.
Any help would be appreciated. I knew I shouldn't have just replaced the coil without getting to root cause...