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Late Beogram 4002 and the 4004 (Types 551x and 552x), which have DC platter motors instead of the earlier synchronous AC motors usually suff...

Tuesday, June 17, 2014

Beomaster 8000: Rebuilding the Filter and Tone Controls Board (PCB #4)

Today I took the filter and tone controls PCB of the Beomaster 8000 out and replaced the capacitors. This required unsoldering the signal strength meter leads from the PCB, and unscrewing the plastic panel that holds the switches, buttons and sliders. Here is a pic from the bottom of the PCB before taking it out:





























The meter in the lower left corner needs to be unsoldered to be able to remove the PCB from the plastic cover. Five screws hold the PCB to the plastic cover. It is important that these screws do not get tightened too much when re-installing the board. The plastic standoffs can easily crack.

Here is a photo of the meter after unsoldering the leads:






























This is a pic of the board after removing it before replacing the capacitors:





























And with new caps:





























Several of them needed to be tilted to accommodate for the low clearance between the plastic cover and the board. This PCB also had one cracked ceramic capacitor (C207).







I replaced it with a new 10nF type:



After screwing the plastic cover back on (it is a bit difficult to get all the buttons and sliders slotted at the same time - patience helps...;-) I soldered the meter leads back onto the board, and tested the Beomaster...seems all works fine. On to the tuner boards.



1 comment:

  1. I think you made a little mistake here. The cracked capacitor does not seem to be a ceramic type, but an excellent quality polyester one. Ceramic capacitors are really on the bottom end of the audio quality scale, and mostly used for decoupling digital IC´s. And this one is placed in the signal path. So if i were you i´d replace it, should you at some point have an excuse to open up the lid.

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