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Beomaster 6500 Noisy transformer/power supply capacitors

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gerardp
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gerardp posted on Tue, Oct 8 2019 10:34 PM

Hi everyone,

My Beomaster 6500 was suffering from excessive noise from the transformer. It was the usual issue with the transformer shoulder washers disintegrating over time. After replacing the 8 washers  and adding extra rubber washers the noise was greatly reduced. Further improved by adding more electrical tape on the transformer to completely cover the windings.

Whilst I have the unit cover removed, I was thinking about replacing 3 of the electrolytic capacitors related to the power supply which show signs of leakage.

I have the values 68uf 16v (C6) and 470uf 40v (C7) on the pcb labelled no 6 which also houses the two voltage regulators (TR3 & TR4)

There is a 1000uf capacitor on the small narrow pcb which houses the main fuse (2TA)  Does anyone know what the voltage rating is for this capacitor? It is not clear from the markings on the capacitor.

Thanks in advance.

Gp

 


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tournedos
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For some reason, that capacitor apparently is not listed in the service manual. I had to go back to Beomaster 5000 to find it. In BM5000, the cap in the same position is listed as 1000 uF / 63V. Seems plausible looking at the physical size of the old cap.

--mika

Weebyx
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Weebyx replied on Wed, Oct 9 2019 12:30 PM

gerardp:

Hi everyone,

My Beomaster 6500 was suffering from excessive noise from the transformer. It was the usual issue with the transformer shoulder washers disintegrating over time. After replacing the 8 washers  and adding extra rubber washers the noise was greatly reduced. Further improved by adding more electrical tape on the transformer to completely cover the windings.

Whilst I have the unit cover removed, I was thinking about replacing 3 of the electrolytic capacitors related to the power supply which show signs of leakage.

I have the values 68uf 16v (C6) and 470uf 40v (C7) on the pcb labelled no 6 which also houses the two voltage regulators (TR3 & TR4)

There is a 1000uf capacitor on the small narrow pcb which houses the main fuse (2TA)  Does anyone know what the voltage rating is for this capacitor? It is not clear from the markings on the capacitor.

Thanks in advance.

Gp

 

What did you use for the replacement washers ? And does the transformer get hotter now it is wrapped in tape ?

 

/Weebyx

gerardp
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gerardp replied on Thu, Oct 10 2019 10:35 AM

I used M6 nylon shoulder washers with a combination of rubber/metal washers. I’ll upload a picture shortly.

With regard to the transformer tape, I have not noticed any extra heat but will monitor this. Looking back I should have just secured the area which was originally taped and was coming away. Using electrical spray glue may have been the way to go. I will revisit this since replacing the washers gave me the improvement I was looking for.  Thanks for pointing this out.

Dillen
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Dillen replied on Thu, Oct 10 2019 12:11 PM

The capacitor is in my manual (and also in the one downloadable from Beoworld).
It's C1 in the DC offset blocking circuit.

Martin

gerardp
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Thank You

Picture of my bolt fixing to cure transformer noise/vibration due to the original washers disintegrating. All parts easily available. The shoulder washer should fit snugly into the transformer bolt holes. I used a little super glue on the shoulder head.

Gerard

 

 

 

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