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Dead Channels on receiver basics?

 

New member
Username: Dv8rdan

Post Number: 1
Registered: Nov-05
Currently I have 3 receivers that have a dead right or left channel. It is bugging me that I haven't been able to fix them. I've searched the threads to no avail.

The one I'm currently in is a Sony STR-DE545. Right channel A+B and rear dead. Excuse me, they are not dead, you can hear very faint output, not amplified. I have reseated the power relays to no avail. I have the board out now looking for clues.

What should I look for if I have a dead channel? What part would power just the rights or the lefts? I would really appreciate the help.

-Dan
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6708
Registered: May-04


Start at the B+ voltage supply and work your way forward.
 

New member
Username: Dv8rdan

Post Number: 2
Registered: Nov-05
That is all well and good, but to know what to do is the problem. Am I measuring for leakage with the power on? It is in pieces right now. This is what I'm looking at.

https://www.vancebaldwin.com/shop/research_new/SON/STRDE545.pdf

Page 12 is the board, schematics before and after. Is there a usual suspect for these sorts of things?
 

Gold Member
Username: Jan_b_vigne

Dallas, TX

Post Number: 6709
Registered: May-04


No. A symptom of a "dead right channel" leaves the diagnosis open to almost anything between the B+ power supply and the output transistors. It is usually best to begin by searching for a spot where voltages no longer concur with the spec. At least one problem exists before that point in the circuit. That doesn't mean other problems don't exist further down the signal path. It is not uncommon for a defective component to alter the subsequent voltages and take out other components as a result of the first problem. You also want to know why the first component went out. Was it fed an incorrect voltage by another defective component in front of it? If so, just replacing a bad cap or diode is only going to eventually blow out the replacement also.


I would make an assumption that the problem exists before the output stages and most likely in the pre amp section. That bit of knowledge only narrows the search down to a few hundred possibilities. This is a receiver full of IC's which take the place of a multitude of discrete components. The possibility of a defective IC would be a good place to start looking.


Do you have experience troubleshooting electronics? What test equipment do you have access to?




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