Beomaster 1900-2 help fixing crackly FM

[Madelvic]

I’m trying to restore a Beomaster 1900-2

The Phone and Tape inputs work fine, but the FM input on any of the 4 presets or 5th tuner is low in volume and crackles

So far I’ve changed all of the electrolytic in the Tuner and IF / Stereo Decoder (reference the Service Manual) but to no avail

Any help would be welcome – I’m basically stuck (and at the limit of my knowledge)

Many thanks

 

 

 

[auric]

Have you changed the electrolytic capacitors C201, C202, C203, (and corresponding on right channel)?

There is also a 10uf cap inside the can.

 

Derek

[Dillen]

A bad MPX chip wouldn’t be a first.

Martin

[Madelvic]

Thanks Derek.  Yes I’ve changed C201, C202, C203 (and the C3xx) plus C23, C20, C99, C27 and recently C18 in the can though not tested it since the last change.   C18 was reading about 17uF so working but well out of range.  I’ve tested C15 but not changed it.

Wondering if I should change the transistors- will stress them with cooling spray first if I can

[Madelvic]

Thanks Martin.   Can do, would you recommend before transistor swaps?

[Dillen]

Yes, I would suspect the IC before any of the small transistors.
Put a scope to the L/R signals from the IC and you will see.

Martin

[Madelvic]

Found and ordered a replacement IC.  Update to follow

 

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