Hitachi Receiver Model SR-604

My circa 1979 receiver is wanting to breath its last but I refuse to let it! I've previously had to have the left channel repaired, now it's the right. Can anyone point me to possible culprits? I've done the obvious checks (switching speakers...) I do not have a service manual for it

Thanks in advance for any help!

 

hi cadman,

you didn't mention if your receiver is a tube or discrete. you have to work your way backwards. you start first by checking the voltages from the left channel and record them. then do the voltage check on the right channel and compare. start checking from the output transistors, then the driver transistors, then the predriver transistor if there is, then the voltage multiplier transistor, then the differential input transistors. any discrepancy that you find is probably the defective part, remove the transistor and do the transistor test, if ok, check the value of the bias resistors and compare to the body band value, if the value is beyond +/-5% or 10%, replace it. then check the coupling caps.

that's all for now.

moz

 

Moz,

Thanks for the tips and I'll give it a whirl.

It's discrete by the way.

-Cadman