Beomaster 8000 left channel drops out

[notwist]

Hi all,

I have done an extensive restoration on one of my Beomaster 8000 machines. It was pristine nut technically in bad shape. Much work was done to make It live again. But It is singing right now.

There is one nagging issue though.  When I go over 4.8 on the volume wheel the left channel cuts out with a loud pop. Dial one step back and it returns. Right channel has no issues. I cleaned all cables and pins to no effect. Both channels are exact duplicates.

Does someone have an idea where to look?

 

Regards,

Bert

 

[Dillen]

Missing bit to one of the volume control ICs.
Or a bad IC.

Martin

[notwist]

Hi Martin,

Are you referring to the ad7110?

How would I proceed to determine the actual cause?  Just janking ics and replacing them seems a bit off. How do we determine what broke?

Regards,

Bert

[Dillen]

No, these are not ICs you would enjoy replacing just for the fun of it.
Put a scope on the control pins and see if everything goes to binary plan when you run the volume up and down.
If it does, swap the two ICs to see if the problem moves to the other side.
If it doesn’t, find out where the missing bit went missing, bad connectors, cracked solder joint, broken cable etc.

Martin

[notwist]

Hi Martin,

The whole pcb was reflowed and all connections cleaned. So it appears to be a faulty IC. Damn. That pcb is a crime to work on 🙁

Bert

[Author]

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