Marantz PM-57 Faulty

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I was playing music through my Marantz PM-57 via the Aux input channel, the source was my Home Theater PC connected via the Front Channel Audio output when suddenly there was no sound, i tried plugging the CD Player into the Aux input and still dead, the both Tape inputs are dead as well, but the Phono, Cd and Tuner inputs still work fine.

Since everything before the Aux works and everything after the Aux has failed i assume there is some sort of link here that has been broken, a burnt out resistor or something?

Also the amp wasn't been driven hard, i live next door to elderly people so never have the music that loud.

Hope someone can point me in the right direction here.

Cheers,
Gerry.
 
After looking at the Service manual Schematic diagram it would indeed appear that 7551 LC78212 controls Phono/CD/Tuner in and 7552 LC78212 controls Aux/Tape2/Tape1 in, so we have a winner! 7552 LC78212 has failed, there appear to be loads of LC78212 IC's available on-line from £3 up to £30, i'm just curious if the quality is the only diffrence or are there different configurations of this chip?

Thanks again!
 
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