We are troubleshooting some problems with the insert lighting on our Flash Gordon (Bally, 1981). Issues should be the same as any other Bally machine of that era.

The pin arrived with incandescents and we didn’t check if they were all working. We’ve now replaced all lights with Comet LEDs, plus anti-flicker boards. A number of lights are always off despite replacing the LED with a known good one. We also had a light that was always on until something (not the bulb) blew.

I understand that these problems can be caused by the fitting, the connection between the fitting and the driver boards, or issues on the driver boards. We have replaced a couple of fittings, but those lights haven’t started working. We have a new light board, but I would prefer not to put it in and promptly lose an SCR due to an undiagnosed short somewhere else.

In particular, I am not succeeding in getting useful information with a multimeter. I am getting 470 ohms across the good LEDs in situ in original fittings, but I don't seem to be able to get anything except an open circuit with the new fittings (either before or after installing them) - neither the resistance mode nor the diode mode is doing anything if I put a LED in the socket and connect the multimeter across it.

Is there anything useful that can be done looking at levels in voltmeter mode? I know the common return wire is high (about +7V relative to the cabinet ground) all the time and the signal wires go low to turn on. But my multimeter can’t respond fast enough to the flashing lamps in lamp test mode so I am getting a kind of squidgy +1.5V on the known good LEDs.

Finally, what is the best way of testing continuity between board and playfield? With the arrangement of sockets on the old Bally lighting boards I can’t find a good place to probe at the board end of the connection.

No. The lights that don’t work, don’t work.

The light that was on all the time was obviously on during test mode.