Voltage measurements on a Studer B67’s motor control boards

The motor control boards are the little ones that have the Rifa capacitors that are known to leak. I wrote about recapping these here.

My friend who’s been helping me figure out what’s wrong with this machine told me to take some voltage measurements on the motor control boards, so I did. I still don’t know what they mean, but I will soon. For future reference (for my own sake and others’), here is what I measured:

Take up motor control board:

Points 3 & 4: 107.7 VAC
Points 4 & 2: 107.6 VAC
Points 4 & 1: 188 VAC
Points 5 & 10: 0.30 VDC
Points 6 & 10: -0.012 VDC
Points 7 & 10: .042 VDC
Points 12 & 14: 189.8 VAC
Points 11 & 13: 106 VAC

I think the voltage between points 5 and 10 is a problem, because it’s deviating from the supply motor voltages, but also I was told it should be high DC voltage.

Supply motor control board:
Points 3 & 4: 100.2 VAC
Points 4 & 2: 100.3 VAC
Points 4 & 1: 95.4 VAC
Points 5 & 10: 139.2 VDC
Points 6 & 10: 0 VDC (this one was exactly zero)
Points 7 & 10: 0.0 VDC (Again, on the nose).
Points 12 & 14: 6.8 VAC
Points 11 & 13: 4.5 VAC

The voltages between points 12 & 14 and 11 & 13 differ, but I think that’s because the take up motor is running at full speed.

I think I’m getting close! I will update this post with what should be the correct voltages when I know them. EDIT: the correct voltages are what showed up on the supply board.

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