Hello!
I have a Sony STR-DH770 amplifier, which sadly doesn't want to turn on anymore.
The way it happened was very dumb, as I was reorganizing cables and so on, when I was plugging it back, seems like some dust/particles got into the socket and when plugging it back in, it made false contact a couple of times, cause I heard the relay click a couple of times, and afterwards it did not want to turn on anymore.
Checked the fuse and changed it, but it made no difference.
Whenever I plug it in, I hear the click of the relay, so I have the feeling that the issue is the main transformer and the stand by transformer is still working, which is a is a similar issue as was posted here: https://www.diyaudio.com/community/threads/sony-receiver-wont-turn-on-need-help.167239/
I was hoping someone can enlighten me on how to properly test the transformer to know if this is the root cause of the issue, and changing the thermal fuse (if necessary)?
Greetings!
I have a Sony STR-DH770 amplifier, which sadly doesn't want to turn on anymore.
The way it happened was very dumb, as I was reorganizing cables and so on, when I was plugging it back, seems like some dust/particles got into the socket and when plugging it back in, it made false contact a couple of times, cause I heard the relay click a couple of times, and afterwards it did not want to turn on anymore.
Checked the fuse and changed it, but it made no difference.
Whenever I plug it in, I hear the click of the relay, so I have the feeling that the issue is the main transformer and the stand by transformer is still working, which is a is a similar issue as was posted here: https://www.diyaudio.com/community/threads/sony-receiver-wont-turn-on-need-help.167239/
I was hoping someone can enlighten me on how to properly test the transformer to know if this is the root cause of the issue, and changing the thermal fuse (if necessary)?
Greetings!
Attachments
There is a test mode in section 3 of manual but I don’t know if it will be operable given your problem.
Study wiring on pages 31 and 39. Confirm AC at input primary of T901 (terminals 1 and 2). Then look for presence of secondary AC voltages. That should tell the story. Good luck!
Study wiring on pages 31 and 39. Confirm AC at input primary of T901 (terminals 1 and 2). Then look for presence of secondary AC voltages. That should tell the story. Good luck!
It seems that the orange and yellow wire is the primary winding, Use a DMM to measure continuity to see if there is an open circuit.
Just wanted to make sure, do you mean there are infinite ohms or "O.L." reading between the orange and white wires?
Thanks, if the meter beeps, it means the transformer input (primary winding) is OK.
Why you post this photo?
Why you post this photo?
@chrisng , the photo was regarding @madis64 comment, that he said it had 3 fuses, I only see one next to the stand by transformer, and as reference that is where the diagram for the STR-DH700 (which is not my model, but still as a reference), shows another 2 fuses, which I don't see on my STR-DH770.
Correct, there is no beep between the input wires and the output wires. How do I know if this transformer has thermal fuses inside? That could be a cause right?
Correct, there is no beep between the input wires and the output wires. How do I know if this transformer has thermal fuses inside? That could be a cause right?
Yes, if the thermal fuse inside the transformer blows, it will cause the primary winding to read an open circuit. However, the secondary winding should not be affected.
Please measure each set of secondary windings to make sure they are still good, otherwise the transformer will need to be replaced, and simply replacing the thermal fuse will not save it.
Please measure each set of secondary windings to make sure they are still good, otherwise the transformer will need to be replaced, and simply replacing the thermal fuse will not save it.
The input and output wires (primary and secondary windings) should not beep between themselves.
What should show resistance (not necessarily beep) are the input wires between themselves and the output wires between themselves.