Pioneer Sa 7300

[Pitagi]

Hi, I was wondering if anyone would be able to help with the repair of my old Pioneer SA7300 amp?



I was using it and all of a sudden there was no sound, I noticed that the protection circuit was not allowing the system to run. I downloaded a service manual and got as far as the power supply which checks out voltage wise ok. it is the model with a hybrid in the O/p stage but I dont think these power amps are faulty. I have been checking out the transistors and diodes in the main amp stage but seem to be having trouble with identifying the components from the Schematic. Does anyone have a layout of the components.



Is there anyone who could advise of any test procedures which I might be able to use to establish which side is faulty, I remember changing one of the hybrids in the mid 80s and at the same time paid for the service manual from Pioneer in Slough but in time it has got mislaid. Now the protection relay will not switch and the system just lays in the pre state.



I have tried the system without load and it is the same, I am thinking of removing one hybrid at a time to see weather i can get it to switch and apart from checking every component is there anyone who can advise me.



Thanks, Peter

[52 Bill]

This is a stereo power amp correct with the large flat amp output modules? The protection circuit usually monitors the power amp output and will shut off the speakers in order to protect them from damage. I'd start by checking for dc voltage on the output pins of the two amp modules.