Beogram 8000: Electrical Work Checkout and Forward/Reverse Voltage Adjustment

After testing some basic Beogram 8000 control functions I am satisfied that the electrical work is done. It is time to bundle up the microcomputer board box so I can move on to the service manual adjustments.

The microcomputer box lid contains a heatsink for the processor device. I had cleaned off the old thermal compound and applied new compound.

The lid attached securely and I can peak in the end and see the thermal compound is sandwiched nicely between the heatsink and processor.

While the main Beogram components are still out of the chassis this is a good time to do some of the service manual adjustments. There is still one that is related to possible electrical tasks and that is the adjustment of the forward and reverse voltages for the tangential arm transport.

There is a common lamp with two photo resistors on either side in the Beogram control panel. One photo resistor (R9) is for forward movement and the other (R10) is for reverse movement. The voltages on those two resistors should be 650mV when the Beogram 8000 has been on for at least five minutes and the Play button is activated (with the tangential arm assembly stationary).

I initially measured around 600mV for the reverse photo resistor (P5-6, R10) and 300mV for the forward photo resistor (P5-4, R9). Here are the measurements after the adjustment.

Here is what the related connector, P5 looks like on the Beogram 8000 control panel.

This picture shows the final position of the forward/reverse adjustment screws.

The relative positions are a little unbalanced to say the least. I will recheck those forward/reverse arm motor voltages again before wrapping up this project to verify the settings are stable.