Loud noise when turning on Beocenter 2002

[Badols]

Hey everyone,

as it says already in the title, whenever I turn on the unit, immediately there is loud noise coming from the speakers, even with no source selected. It does not change when the volume slider is moved.

I have replaced a blown resistor (r201).

Also, when I remove the fuse for the right channel it does not occur, but only a very weak signal come through the left channel.

It occurs on the speakers and the headphones.

Any help would be appreciated!

Jonathan

[Mark-sf]

Are you certain it was R201 3.3K ohms that was burned? I ask because that is a series input resister to the power amp IC and i can’t see it getting the current to “blow” it. If that is the resister, could it have been cracked instead? As to the noise can you describe its character. Can you check if you are getting a DC voltage on the output with the speakers disconnected?

[Badols]

Hey Mark-sf,

As for the resistor, it was r101(!), which is the same resistance of 390 ohms. I will add a picture of the resistor before it was replaced.

 

 

 

 

 

 

 

 

 

 

 

 

 

I measured for DC output:

Left channel: 24.48

Right channel: 0

I played around with all the sliders, volume, bass etc.. No changes.

 

The character of the noise is ver loud crackling and buzz/humming.

Could it be the right IC module?

[Mark-sf]

I’m not sure what that circuit board’s function is as it’s markings and wiring could indicate that it is on the power amp outputs. You definitely have a defective left channel if it is reading 24v. That is also the channel associated with the R101 that you replaced. Fix the left channel first and you may find that the right channel no longer makes noise.

[Author]

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