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8190 Crackle issue


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#1 neiloliver

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Posted 31 July 2019 - 02:39 PM

I have a problem with an 8190 I am restoring.

 

When on radio or line in, the left speaker gets a static crackle which is there regardless of the volume control position.

 

Often it will die away but then comes back randomly. I am sure it is not a pot issue as they have all been cleaned and none crackle when moved. 

 

I have replaced all of the electrolytic capacitors around the power amp section and the two transistors on the heat sink (but not the amp itself).

 

Note that the tape is not really connected up at the moment because to get the the two boards I have had to dismantle virtually everything.

 

Note the crackle will happen if I am touching NOTHING on either board so I don't think it is a loose connection.

 

I can continue and replace all of the caps but I am still not sure it will fix the problem.

 

 

Any idea what could be causing this?

 

thank you

Neil



#2 baddboybill

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Posted 01 August 2019 - 04:41 PM

You didn’t mention cleaning any switches like function or band and especially recording bar switch?

#3 hopey

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Posted 01 August 2019 - 10:34 PM

The voice coil could be damaged compare the impedance readings of each driver with a multi meter

#4 neiloliver

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Posted 02 August 2019 - 01:27 PM

I have removed and cleaned the record bar. I have blasted the function switch the best I can. I will try checking the coils. Thanks