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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...

Sunday, February 11, 2018

Beomaster 6000 (2702) restoration: start of reassembling !

Before starting the reassembling I decided to use a piece of wood to put all the different PCB's, frame's, etc. on. The idea is to test the complete Beomaster while on this wood surface and before mounting it back into the frame. By doing this, you have a bit more space around the different parts that allow checking/fixing before final mounting.

During this "operation" I noted a few things that I wanted to address. The first one was the output stage PCB (#11). This long PCB is placed in a narrow subframe. A very narrow place, packed with wires. The PCB is not really fixed and tends to come out every time you handle it. I wanted a permanent solution to remedy this design flaw.

So I constructed two pieces out of aluminium that were glued on both sides to keep the PCB firmly in place.


They can still be bend slightly whenever the PCB needs to be taken out again.

The second issue was that one of the input DIN5 connectors started to show a possible los of one of the wings (like what happend on the speaker connector). It was replaced with a "new" one.

The piece of wood I used was a 70 x 40 cm OSB type. I had a larger piece laying around in my garage and cut it to measure.

The level and pre-amplifier PCB's where mounted on the output subframe as well.

And now with the SQ decoder fitted as well.

I like to use my iPad Pro to take pictures of everything I dis-assemble and then use the pictures when re-assembling. Off course the service manuals do provide you with all the needed information, but pictures are handy. And it wouldn't be the first time that errors are found in manuals....Or changes that where made during production that never made it back to the drawing boards for modifying the schematics !

The large output coupling capacitors that are mounted on the black frame with the speaker, input, antenna connectors needed replacement as well. They are fixed with a metal bridge onto this frame. Whenever possible, I like to use new capacitors (in this case Nichicon,  4700µF, 105C type) with the same diameter as the old one. This allows to use the existing metal bridges. Since modern capacitors are smaller than the old one (for the same value), the added advantage is that, keeping the same diameter, they are shorter. This allows for easier connection.

The bridges are off course cleaned and polished first !

And then fitted onto the frame.

It may not look like a Beomaster 6000 quad yet, but it is all starting to come back together !

But still a long way to go...... Keep following my posts !

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