Harmon Kardon AV25R MKII playing up

[andjur78]

The owner states that the unit intermittently looses audio on the LHS channel and the system powers down /up.
Checked all solder joints,sockets etc. Cannot fault it one the test bench. Can anyone help with this unit?

 

[derguteton]

check this

http://manuals.harman.com/hk/Service Manual/AVR25II sm.pdf