Michigan Beogram 8002 Restoration: Scanning LDR Assembly

Here is a quick update on the Beogram 8002 restoration project from Michigan.

I left off with the Forward and Reverse scanning control not able to adjust to the values specified in the service manual.

To fix that I knew I would have to replace the two LDR devices and/or the light source.

It turned out that the two LDR devices measured pretty close to each other when testing them after I removed them.  The problem appeared to be with the light source.

I removed the original incandescent lamp and installed an 5mm LED with a 3300 ohm current limiting resistor.

I also tested a couple of new LDR replacements but none of them were as good as the two original devices.

The new LED light source worked great and I was able to adjust the forward and reverse scanning voltages to very close to the target 620mV for the "off" state of the buttons.

I tested the basic Beogram 8002 Play, Stop, Forward, Reverse operations with this updated control panel and it performed just as I expect it to.

With the Beogram 8002 components opened up like this I will solder on some test wires to measure the position sensor, record detect sensor and the platter speed sensor.

Looking at those on an oscilloscope will show how healthy those signals are.

The results of those tests will be in the next post.