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Old 11th Jun 2021, 11:23 am   #1
hkutluk
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Default B&O beomaster 3000 stereo lamp

Hallo friends,

I have a problem of the stereo lamp which dosen't work. of course the lamp's OK.
Radio works perfect except the light.
There is no faulty semiconductor or any other component.
I have tried some ferrite and turned back the original positions. nothing have changed.
Is there any idea about the problem.
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Old 11th Jun 2021, 11:57 am   #2
HECTOR63
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Default Re: B&O beomaster 3000 stereo lamp

Have you checked to make sure its not got the Mono Switch selected on the tuner? Daft but worth a check otherwise start looking at the detector stages etc with a scope-does seem a bit odd and assuming you have carried out the checks of lamp etc incircuit with voltages etc from drivers etc?
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Old 11th Jun 2021, 1:49 pm   #3
HECTOR63
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Default Re: B&O beomaster 3000 stereo lamp

https://en.wikipedia.org/wiki/List_o...ions_in_Turkey

Nice line up of radio stations too!
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Old 20th Aug 2021, 9:15 am   #4
hkutluk
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Default Re: B&O beomaster 3000 stereo lamp

Surely I've checked voltages and all the transistors of the detector stage. I unfortunately don't have any scope. Sometimes not the center but side of any station (when the sound is dirty) the stereo light turns on but not on the center and of course when the light is off there is no stereo effect.
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Old 20th Aug 2021, 9:17 pm   #5
majoconz
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Default Re: B&O beomaster 3000 stereo lamp

hkutluk said:
Quote:
when the light is off there is no stereo effect.
So the stereo indicator light being off is telling the truth - the fault is actually in the decoder. Does it have a chip to do the decoding or the old fashioned 19kHz switching circuits? Often the lamp is driven from an amplified sniff of the 38kHz waveform right at the front of the decoder - the fact that the lamp flickers when off-station makes me think that the tuned circuit or PLL is not tuned correctly.
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Last edited by majoconz; 20th Aug 2021 at 9:29 pm.
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Old 21st Aug 2021, 10:06 pm   #6
Analogue man
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Default Re: B&O beomaster 3000 stereo lamp

This may seem like an obvious question but is the reception of the tuned radio station strong enough to light the lamp, weak signals often won't.
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Old 9th Sep 2021, 6:23 pm   #7
hkutluk
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Default Re: B&O beomaster 3000 stereo lamp

It is old fashioned. There is no decoder chip nor a pll circuit. There is an attachment of the schematics in my post.

Quote:
Originally Posted by majoconz View Post
hkutluk said:
Quote:
when the light is off there is no stereo effect.
So the stereo indicator light being off is telling the truth - the fault is actually in the decoder. Does it have a chip to do the decoding or the old fashioned 19kHz switching circuits? Often the lamp is driven from an amplified sniff of the 38kHz waveform right at the front of the decoder - the fact that the lamp flickers when off-station makes me think that the tuned circuit or PLL is not tuned correctly.
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