Beomaster 1400

[astro]

Hi! I bought two Beomaster 1400 on an advert. One of the 4 sliding knobs is broken (for bass adjustment) Anyone got a spare? Also, one of the channels only give a weak, distorted sound. I have checked the speaker and its ok. I have also cleaned the potentiometers. So I guess there is something wrong with the electronics. Anyone got a clue? Are there any common problems with these beautiful machines?

Cheers, Göran, Sweden

[Dillen]

Knob here.

The missing channel could be caused by one or more dead capacitors.

Martin

[astro]

Dillen wrote:

Knob here. The missing channel could be caused by one or more dead capacitors. Martin

Thanks Martin! The big electrolytic capacitors were all leaking, so I ordered some new ones. See if I can order that sliding knob also. Another thing that is broken is the flywheel for the tuning. Theres supposed to be a connecting plastic cog which has disintegrated. I guess that one is unobtainium.

Ill get back with a report if the  new capacitors did any good.

Cheers, Göran

[Dillen]

The broken tuning part is (was) merely a friction clutch.
Beomaster 1400 (M/K) was produced in the late 1960s, and since 1980 there were no more working clutches. They had all disintegrated due to the choice of material.
Luciky, the tuning will work fine none-the-less, – just without the flywheel effect.

Martin

[astro]

I changed the three big capacitors, and the sound is great- in one channel. Tried the different inputs too. The other channel is still weak and distorted. Could be a million things I guess, but are there any more common problems? Btw, the tuner is really good, picks up lots of stations.

Cheers, Göran

[Dillen]

Capacitors, capacitors and capacitors.

Martin

[astro]

Hi again! There is a pot (737 in the schematics) that is a bit charred. I think it is related to the channel (right) that is weak and distorted. Is it a good idea to change the caps in this area of the board?

cheers, Göran

[astro]

Also, the right hand side transistor mounted on the rear heatsink gets varm.

cheers, Göran

[astro]

So, a update, I changed some caps and it got the radio scale light working. Then I checked the output transistors and they seemed fine, all measured the same with the diode tester. But when I put the transistors back the radio sounded great from both channels. And the heatsink is much cooler.

Thanks Martin for the hints!

cheers, Göran

[Author]

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