AMI Rowe CD100F : All lamps do not light

[Rowe_Rookie]

I have a CD100F that I'm restoring.  At one point, all the lamps except the ones in the middle (Animation Left and Right) were operational.  (The Animation has its own problems that I'm not worried about at this time). Recently, the lamps on the Price Card right side stopped working.  In the process of troubleshooting it, all the remaining lamps (AMI Disc Left and Right, and Price Card left side) stopped working.

There is a 9 pin connector that provides 28VAC to the light the lamps.  A yellow/black wire pair are then spliced together to provide power to a group of lamps.  Each group of lamps has its own separate two pin connector.  The lamps within a group are connected in series.  Here is the troubleshooting I have done so far:
1)  Removed the small printed circuit board (34002201 Rev D)  which houses the Price Card right lamps (2 lamps in series).  Although the lamps (Incandescent Type 73, 1 Watt, 14V)  are intended to be powered off 28VAC when installed in the jukebox, I was able to light the lamps using a 9Vdc battery.  The lamps were dim when connected to the battery, but this proved that there is nothing wrong with the pcb or the lamps.
2)  With a voltmeter, measured the voltage at each of the 2 pin connectors when they were each disconnected from the printed circuit boards housing the lamps.  They each correctly read around 28VAC with no load.
3)  Installed only the 2 pin connector for the Price Card right lamps.  I then measured the voltage by connecting the voltmeter directly to the traces on the 34002201 pcb.  It measured zero across the two lamps.  It should have read 28VAC.  Also, since all the 2pin connectors are spliced together, I measured the voltage on any of the two pin connectors when the pcb was installed, and they all read zero volts.


So the problem is that the 28VAC dropped to zero when the load (i.e., the lamps) is connected.
Next, I disconnected the 9 pin connector.  Using some 24AWG wires, I connected the pcb directly to the 28V pins coming from the 9 pin connector by forcing the 24AWG wires into the 9 pin connector  pins that provided 28VAC and return.   Again, the voltage dropped to zero across the pcb traces.    This tells me that the problem is not with any of the two pin connectors or the splicing.  The problem goes back as far to at least the 9 pin connector. 
One final experiment.  I had a 1 Mohm resistor.  Using some 24AWG , I connected the resistor across the 28VAC and return coming from the 9 pin connector.  The voltage did nto drop;  it stayed at around 28VAC.

Thanks in advance for any help.

[Rowe_Rookie]

It appears that the root cause of the problem can be traced to two 5.6ohm 5W wirewound resistors (Ohmite TUW5J5R6) which are in series on the 28VAC line.  Coming out of the Power Module, there is a cable harness whose yellow wire is routed to the lower end of a terminal block.  The terminal block then has one 5.6ohmn resistor on each side.  The upper end of the terminal block then carries the 28VAC to the lamps via a different yellow wire.  So the lamps are effectively powered by 28VAC with a 2.8ohm equivalent resistor in series.  Upon removing those two wirewound resistors, it was discovered that neither measured 5.6ohms!  One part measured about 7.1Kohms and the other did not register at all on the ohmeter, indicating that it was an open.  Apparently what has happened is that these two 5.6ohm resistors failed, possibly at different times.  I can't tell if it was the result of exceeding the 5W rating, or just normal failure of a component over time.  So, I have ordered replacement parts and hope to have them in a week.  Then I will be able to swap the old parts with the new ones, and see if that gets the lamps to turn on.   I'm reasonably sure this is the problem.  Basic Ohm's Law would show that with such high value resistors in series with 28VAC, virtually all the voltage drop will be across the resistors and there is nothing left to power the lamps.  I'll provide an update after the new resistors arrive, and I've had a chance to try them out in the Jukebox.