BEOMASTER 4400 AFC problem

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Maciej Zietara Posted: Tue, Oct 16 2018 11:32 AM

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Hi everyone,

I am restoring right now Beomaster 4400, I recap all electrolytes, and the beast came alive, no signal current are set  - sounds beautiful!
Phono 1 and 2 works perfectly, FM also tune nicly with stereo. I found out one problem with AFC and I am stuck.

In FM mode when I swith on AFC function it mute both chanels, even with strong stereo signal. I can tune the signal but ther is a shift in comparison to (AFC OF) and the volume is decreased around 8 times when AFC is ON.

I have checked conections on AFC button (77 and 80) seems to be ok,
and also tranzistors TR7, TR8 and TR9 they are all good.

Any idea... suspections, experiences.. ? wich might be helpfull.

Regards,
maciej

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Dillen replied on Tue, Oct 16 2018 12:43 PM

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The AFC function is strongly related to the muting circuit.
The button is labelled AFC-ST, where ST stands for Silent Tuning (muted between strong stations).

Most of the problems in these areas are caused by wrong wattage tuning discriminator lamps.

Martin

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Maciej Zietara replied on Tue, Oct 16 2018 3:52 PM

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Thank you Martin, I will try to play a bit with this area.

maciej

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Maciej Zietara replied on Thu, Oct 18 2018 1:58 PM

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Hi Martin, you were right, I have changed the bulbs and it works perfectly.

Thank you,
maciej