RX V380 Yamaha with intermittent DC protection fault

[fafapiti]

Well, here is my first post guys. After browsing through the forum, I could not find a similar issue I have with my RXV383.
The last few weeks I noticed a little Pop in the left speaker immediately after turning ON the receiver, but nothing to worry about, I thought.
Last week the first DC protection occurs, which triggered a frenetic research on the net to gather all the information I could get. After 3 restarts the receiver went into lock mode, as expected, but I managed to reset the microprocessor into the service mode as mentioned by different people.
Amazingly from there, the receiver worked well for the rest of the day.

Unfortunately, the following day the receiver went into DC protect again, and again after few restarts the receiver turned ON and work flawlessly…until the following day.
I decided to grab my multimeter, disconnect everything from the receiver and put the system in service mode with protection override. I found less than 20mv on right and centre channels but -6VDC on the left channel and going down slowly to reach 16mv a couple of minutes later. Of course, after that, I could restart the receiver with no issue.
I did the same test the following day, with the multimeter already connected while I was putting the receiver on service mode straight away at the first start. The reading was -25vDC and gone to -18mv 5 minutes later…

I have the feeling there is a capacitor issue somewhere, maybe, but where to start? If you have any ideas to help me source the issue I will be really pleased. I am electrician with basic knowledge in electronics.

Thank you all

[sam_sam_sam]

Re: RX V380 Yamaha with intermittent DC protection fault

I would replace all the filtering capacitors for audio output and in coming power supply first I would also replace capacitors that are less than 100uf capacitors

[R_J]

Re: RX V380 Yamaha with intermittent DC protection fault

You likely have a poor solder connection in the left channel, that is the channel with the high Dc offset. Check this DC OFFSET voltage for this channel when the amp is working, is it still -6v~-25v or is it near 0vdc when it's working. If it IS near 0 volts, try tapping around that section using an insulated stick to see if you can get it to act up while monitoring the voltage.