Featured Post

Beogram 4002: Restoration of DC Motor Video Published - Check It Out!

By popular request (really, I got quite a few emails about this!...;-), I finally completed my Beogram DC motor restoration video! It demon...

Monday, September 21, 2015

Beogram 4002: Replacing the RPM Indicator Bulbs with SMD LEDs

I continued working my way through replacing the lightbulbs in the Beogram 4002 (5513) that I am restoring right now. Today was RPM indicator day. I took this as an opportunity to further improve my LED replacement approach. In an earlier post I described how to replace the incandescent bulbs with the red and green LEDs of a RGB through hole 5 mm LED. This worked fairly well, but I was not 100% happy with the homogeneity of the back illumination of the RPM trimmer scales. The issue with standard through hole LEDs is their directed emission pattern out of the top of the LEDs. This made it necessary to sand their bulbs into a matte surface and also painting the tops black to prevent a too high emission on one side of the trimmer scales. 
My latest approach is based on my current approach to implanting LEDs for the position scale illumination of Beogram 4000s. I changed the PCB shape to fit behind the bulb covers of the 4002 bulb housings, and I adapted the current limiting resistors (10k for green and 2.5k for red) to the 21V operating voltage and the different illumination angle of the diffusing cavity. I made a short video about this updated approach:



3 comments:

  1. hi there, i have just bought a basket case of a 4002 so i think you are now my got to guy!

    Do your have a set of these led indicators for sale currently for the rpm adjustments panel?

    i was also having issues with the threaded arm that drives the tone arm carriage. it seems to be caused by the black plastic @washer@ that guides the brass rod just before it goes through he metal mount and into the pulley wheel for the motor belt. should that piece of black plastic be in too parts? and should the metal mount be vertical or bent over slightly towards the turntable. not sure if some one has been mucking about ! if washer shouldn't be in two parts do you have replacement? i know this description sucks to i can email a picture !

    ReplyDelete
  2. I just watched your video on replacing the RPM bulbs with SMD LEDs for the 4002. How cam I get them? and how much are they?

    ReplyDelete
  3. Hi, I have a 4002 type 5503 and need replacement bulbs for my speed indicators. The ones you replace look different than mine as mine are bare bulbs. Will yours work for me.

    Thanks, Jim

    ReplyDelete

Comments and suggestions are welcome!