Installing a shaker motor in AC/DC, brand new parts. I actually read and followed the instructions--I know, shocking! Powered up, checked the game settings, played a couple games, nada. Completely dead.

Traced back through the wiring, everything looks correct. Proper connectors, no misaligned wires, everything connected tight. Pulled the motor and tested it on a bench supply at 12 VDC, it turns.

Found a meter and tested the supply voltage to the shaker driver board. According to the docs, power on the 7-pin connector should be 16 VAC but I'm seeing 8.3 VAC so that seems way off. Can someone with a shaker installed in a recent Stern verify the voltage across pins 1-7 on J1 of the motor driver board (#520-6803-00).

Many thanks.

This turned out to be caused by a wiring harness error from the factory. It is a simple mistake and was easy to fix. But it should have been caught by the QC process when the harness was assembled. I will post details of the error and fix here in case it can help someone else.

There is a harness that comes with the shaker kit that has a long black/yellow wire to provide ground to the shaker motor driver board. One end of the black/yellow wire connects to the shaker motor driver PCB, the other end connects to J16 on the power/driver board in the backbox.

The backbox end of the harness is inserted in between J16 and the existing wiring playfield harness. The black/yellow wire connects to J16 on the power/driver board to provide a ground signal. The existing playfield harness then plugs into a Z-connector on the shaker harness that connects it back to J16.

When the Z-connector is installed at the wrong end of the harness, the black/yellow wire is not connected to anything so there is no ground reference for the shaker driver. The Z-connector MUST be installed at the end of the jumper cable WITHOUT the black/yellow wire.

Also, once everything was working I checked the supply voltage to the shaker driver board and it is about 10 VAC, not 16 VAC. Everything works so I have to assume that correct.

John_I, my board says Rev B so I thought I had the right part but it is clearly a different part. I will add that board to the list of parts I need and swap it out. Thanks for the help.