I posted this in the Transport The Rescue fanclub but I thought it would get better visibility here. I am trying to get two flashers working. I have confirmed via wire colour-coding that the two flashers circle below are "JET FLSHS C SIDE 05 04"

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The wire colour-code to both of these is black-yellow. These two flashers are part of the "special" solenoids.

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I've dealt with a similar problem in the past and it was the TIP122 at fault but I decided to go through the motions anyway to help train my brain with problems like this. I put the game in diagnostics mode, coil test, and then to the JET FLSHS. I put my logic probe on pin 6 of U20. The signal was pulsing so I followed the signal path to Q20, and then to Q24 and finally to 1J11-5. It pulsed the entire way, so my initial hunch of it being Q24 didn't pan out.

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On 1J11-5 the wire colour-code changes to gry-yellow. I followed this around to the Aux. Power Driver Board. Using my DMM I checked for continuity from 1J11-5 to the far end. All good.

So I moved to under the playfield. I'm measured 38VDC on each flasher (they are in series). So I followed the black-yellow back to the Interconnect Board in the backbox and check it for continuity. All good.

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So it's not the bulbs. I checked. I even swapped both with known good bulbs.
So it's not U20.
So it's not Q20.
So it's not Q24 (the TIP122).
It's not a break in the wiring from the CPU Board to the Aux. Driver Board.
It's not a break in the wiring from the flasher to the Interconnect Board.
The flashers are getting power.

This leaves me at something possible wrong on the Interconnect Board. Unless I skipped something? Any help would be appreciated.

Thank you,
Tim

No responses. I'm more than a little disappointed. Then again, this forced me to continue looking at the problem.

I tested each of the transistors again. Starting with the smaller driver transistors. All of them fell within the .4 to .6 spec. I wasn't ruling out a possible bad transistor, but so far they were looking innocent. U20 I tested with my logic probe. It was pulsing and I was able to follow the pulse all the way through.

I was so sure the problem was going to be on the CPU, but after looking at all the components again it was looking like my problem was going to be found elsewhere. I moved onto the Aux Driver Board. Diodes all checked out, but when I measured voltage on J5 my meter showed less than 6 volts. Hmm...

There was 6 volts coming into the Aux Driver Board and 6 volts going out. So I went back to the CPU. 6 volts on 1J11-5. So I moved down to the Interconnect Board. I've never owned a pin with an Interconnect Board, but I like the idea of having one place to do all your shopping. The wiring from the CPU and Aux Driver Board start/end here (depending on how you look at it). The one thing I did notice though is that my DMM was reading 6 volts here as well. So I started measuring across the tops of the ceramic resistors. When I got to R4 it measured 6 volts, but when I moved my lead to the other side it read a nice 40 volts.

Turns out R4 was my issue. 40V from the flasher under the PF runs to R4 over black/yellow wire. Through R4 and then to the Aux Driver Board and finally to the CPU. I have not replaced R4 yet, but I am confident this is my problem.

Special thanks to dozer1 for pointing me in the right direction.