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Beomaster 1000: Hum from the power transformer

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This post has 9 Replies | 1 Follower

DancingWave
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DancingWave Posted: Mon, Mar 16 2015 12:19 PM

Dear all,

My first post here :)

I have a Beomaster 1000, which was working nicely and creating a clear audio when I listened to radio stations.

However, I just noticed yesterday that, there was a noisy sound coming from the transformer. I mean, inside of the body itself, not from the speakers.

I also tried to turned the volume to zero and still could here this noisy "hmmmmmmm" sound from the inside. I also switched the speaker to Speaker 2, which I am not using, to cut the speakers connected to Beomaster 1000. Still, I could here the "hmmmmmmmm" noise from the inside.

How should I do ? I can do some repair by myself based on my electronics knowledge. But I don't know exactly which part I have to take care of ......

 

Please suggest :D

 

DW

Lee
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Lee replied on Mon, Mar 16 2015 12:58 PM

Sounds like the transformers is becoming de-laminated. Not a lot you can do about it unfortunately, its just one of those things with old transformers. You could check to see if the transformer is screwed down tight to the chassis or try placing the amp on a some rubber feet to reduce resonance.

 

Dillen
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Dillen replied on Mon, Mar 16 2015 1:19 PM

Welcome to Beoworld!

I agree with Lee, unless the Beomaster gets unusually hot underneath the front.
The bottom plate doubles as cooling area for the output transistors and the voltage regulator, so
if f.e. the idle current setting has run astray, the bottom plate will get warm and the transformer overloaded, causing hum.
The Beomaster bottom plate should normally not get any warmer than your hand and that's even when playing at considerable volume for a long time.
If all temperatures are normal, the problem is with the transformer itself. A couple different types of
transformers were used in the Beomaster 1000 production, some will hum along happily for years while at least
one type is known to break down and eventually heat itself up to the point of smoking and smelling.
If the latter type, I suggest replacing it asap.
What is the type number of your Beomaster (range 2301-2317) ?
Or, even better, can you provide us with a photo of the transformer?

Martin

chartz
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chartz replied on Mon, Mar 16 2015 4:52 PM

Is there any chance the bridge rectifier has lost a diode?

Jacques

Dillen
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Dillen replied on Mon, Mar 16 2015 5:40 PM

chartz:

Is there any chance the bridge rectifier has lost a diode?

A missing diode would cause hum from the speakers rather than the transformer.
However, a shorted diode in the rectifier could cause heat buildup in the transformer, but I would think performance and
functionality would suffer too, then.

Martin

chartz
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chartz replied on Tue, Mar 17 2015 6:24 AM

Oops I hadn't read the first post correctly. Sorry!

Jacques

DancingWave
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Hi all,

Thanks a lot for your warm welcome to my first post and to be concerned with my first BeO product :D

 

I will provide the part number of my Beomaster 1000 and will try to take a photo of the transformer and will post again.

 

DancingWave
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Hi Martin,

Thanks a lot for this fruitful information. I will try to take the photo of the transformer and will post also the type number.

In case that I would need to replace the transformer, where can I buy this part ? Is it a general power transformer that I can order from any electronic shop ?

DW

Dillen
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Dillen replied on Tue, Mar 17 2015 8:40 AM

No, it's not a commonly available part but, depending on the type (some were territory specific), I may be able to find something in the dungeons.

Martin

DancingWave
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Hi Martin,

 

As I checked my Beomaster 1000, I found the following information:

 

NR 1000, Type 2317, serie 04 GODK

No. 77395.

 

Any chance to fix this hum or replacing transformer with a new one ?

Thank you very much,

DW

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