Hi guys i have a sony receiver where the rear right channel is not working, all other channels r working, speakers all good switched them around to check ,still rt channel ng nothing comming out of speaker any advise?
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Sony STR-DE725
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Re: Sony STR-DE725
With Plain Bill's service manual schematic in hand, start with the defective side's speaker terminal, and work your way back. I didn't check the PDF, but some units do have output fuses (rare these days) so be on the lookout for that. If there are discrete (transistor/MOSFET) output devices, you can check them for shorts (collector to emitter). Also look for signs of overheating near the big heatsink...even if the insulating washers are distorted, or the board under the device is browned you may have found the problem
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Re: Sony STR-DE725
Check the output transistor, Q757 on page 21 of the schematic, for a dead short (zero ohms) with your multimeter. You can check it incircuit if you have a DMM, or remove it to be sure. This appears to be the output section for the rear (surround) portion of the audio amp. It appears that the protection relay circuit protects both left and right with the same DPDT relay, so if you hear sound from the left, its probably not the protection circuit.
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