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Beolab 4000, would one tiny resistor stop it from working?

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berni2907
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berni2907 posted on Wed, Jan 20 2021 11:50 PM

Hi There

I have a pair of Beolab 4000 mk1, one of which works fine and the other powers up but no sound. I have removed the gunky foam, and the main (large) board has just one corroded spot on it. A tiny SMD 100 ohm resistor appears to have bitten the dust. Ot perhaps eaten the acid would be more correct. Would that give the symptom I describe possibly?

Two fuses were covered in a white dust, but test good.

Also what else should I change while I am there?

Thank you in advance!

Berni

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berni2907
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Hi

Picture of said resistor.....

berni2907
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Hi

Picture of said resistor.....

Designed-AV
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Quick question only, after you changed the resistor did the speaker work or not?

Keith Saunders
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Common problem with early BeoLab 4000's and caused by black foam rot


Regards Keith....

Beobuddy
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You’re lucky with this one. You might expect more damage than your eyes can see at this moment. The other one from the set will have more severe damage unfortunately. These “version D” boards are at an age by now that the foam has had years to “eat” more surfaces and traces which are probably beyond repair. 

berni2907
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Hello

Actually, much to my surprise, yes it did! I was pretty happy! 

That 100 ohm resistor must be part of the circuit that wakes up the speaker when it detects an input.

All the best

Berni

berni2907
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And thank you very much for your input guys!

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