B&O Beomaster 901 - Buzzing/Hum Sound

[AndrewD]

Hi,

I have been gifted a Beomaster 901 tuner/amp that is linked to B&O speakers and a Beogram 1202 turntable. It has not been used for several years. When I first turned it on the sound was fine, although there was a crackle when moved the volume control of the speaker slider, however the tuning for the radio did not work. I noticed that the tuning cable was snapped which I have fixed. When I then turned the system back on with the volume set to 0 there was a hum from the speakers. As I increased the volume slider the hum turned into a loud buzz. Moving the speaker slider did not make a difference, however moving the bass slider did. With slider to the left the hum/buzz reduced, moving slider to the right increased the Hum/Buzz.

I am not an electronics whizz, has anyone out there got any ideas please, could I have disturbed something when fixing the tuning cable?

Regards Andy

[Edward Huggins]

Spray all those sliders with Servisol from Maplins and work them in. You mention a "speaker slider" what's that?

[AndrewD]

Hi Edward, thanks. The speaker slider fades in/out each speaker.
Andy

[Records]

I think he means the unit has slide controls rather than knobs, the sliders can suffer from dust getting into them

[Michael Maurice]

What you may find is that the volume control is not a slider but a rotary control driven by a cord from the sliding control. It is the rotary section that requires cleaning.

Does the buzz occur on all inputs, ie tape, gram and radio.

It does sound like you may have disturbed something but surprised that it affects both channels.

[AndrewD]

Hi Michael, many thanks for your reply. Yes the volume control is a rotary driven by a slider and cable. So I will look at that along with the others.

The hum/buzz is apparent in all modes (phono, radio and tape, although I do not have a tape player attached).

When switched off there is a faint hum, but it is when the system is switched on the hum/buzz is most noticeable as it drowns out any music from any means (phono/radio).

Regards, Andy.

[Station X]

Are the volume slider and speaker slider the same thing?

[valveaudio]

For 'Speaker Slider' read Balance Control.

Trevor

[Station X]

Got it!

[Grubhead]

Originally Posted by AndrewD

The hum/buzz is apparent in all modes (phono, radio and tape, although I do not have a tape player attached).

When switched off there is a faint hum, but it is when the system is switched on the hum/buzz is most noticeable as it drowns out any music from any means (phono/radio).

As the hum is on everything it will probably be the power supply capacitors. You will need to replace them. They will be the biggest ones. There could be just one large one, but if there are two replace both. Replace any other capacitor that doesn't look normal.