This is a follow up to my recent post about the redesigned Beogram Commander remote control board, which now works in both (DC-motor) Beogr...
Tuesday, May 5, 2015
Beogram 4000: Restoring the Slow Slide Transport Function
The Beogram 4000 that I am currently restoring had a tendency to continue moving the tone arm carriage ("slide" in the service manual parlance) whenever the carriage was moved fast or slow in reverse direction. It turned out that the keypad switch that controls the reverse direction was damaged due to an earlier repair attempt where the contact terminal was bent, with the result that the turn off contact was not stable anymore. Here is a picture of the terminal as I found it:
In order to fix this I had to remove the control panel, take out the circuit board and extract the switch terminals. This allowed me to bend the contact terminal back into shape and also clean the contacts throughly. This fixed the problem. I made a short video about the process. It discusses the slide transport circuit, how to remove the contacts and clean them and how to adjust the slow scan speed to specifications:
This shows the switch taken apart:
And the terminal after I straightened and cleaned it, and soldered it back in:
After I was done with the contacts, I also fixed this solder iron inflicted damage from some earlier repair-shop stay that left the conductor exposed:
I put some 1/16th shrink tubing on the damaged wire and soldered it back onto its terminal:
The next step is to put in a LED based replacement for the tracking sensor.