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...
Monday, September 19, 2016
Beogram 4002 (5501): Restoration of RPM Trimmer Panel
After rebuilding the PCBs of the Beogram 4002 (5501) that I am currently restoring, I turned my attention to the RPM trimmer panel. This panel had been replaced previously with the aim to repair a burned out trimmer scale illumination bulb. As a first step I re-worked the solder connections in the wires where the original panel had been cut off. This shows the situation when I received the deck:
I re-soldered all connections and installed proper diameter shrink tubing to protect the solder joints:
Then I replaced the bulbs with my LED replacement boards:
These are specially designed for the 550x Types since the bulbs partake in the RPM switching process, i.e. the LED circuits need to present a similar resistance/current draw as the original bulbs.
Like all my parts, these boards are available to other enthusiasts. Just send me an email, or use the contact form to the right. This video shows how to install the LED boards.
This shows the original situation (I already had removed one bulb when I remembered that I needed to take a picture...):
Then I installed the LED boards:
then I briefly confirmed that the LED replacements worked properly, and then I removed the white plastic fixture from the aluminum panel, since my customer wanted to use a different better-conditon panel instead of the one that was installed. This required to cut off the retaining rings on the aluminum posts after which I was able to remove the assembly:
What I found were already wavy white background strips that serve the back illumination of the ed RPM indicator hands. Wavy backgrounds cause inhomogeneous back illumination, i.e. they are better replaced if long term stability is desired. I usually replace them with white electrical tape:
After that I put the assembly on the new aluminum panel attaching it with M3 circlips and nylon washers. This shows the final outcome with the bulb covers installed over the LED panels:
And here an impression of the front side with 33 RPM selected:
Pretty! And it looks warmly incandescent (a result of using red and green LEDs to mimic the emission spectrum of incandescent light bulbs). All good again in the RPM panel department!