Hi everyone
I've acquired a faulty Onkyo HT-R390 receiver - it's very low spec with "monolitic" amplifier ICs. It's mostly an exercise for me.
It would not power up (It would shut down immediately).
I believe I found one of those monolitic chips shorted so I ordered a new one.
However, the amp still has trouble powering up.
It's a bit weird. I know the amp works - I plugged a source and a speaker and I had sound from both channels but at least one channel had some noise in the background and if I wiggled the input RCA the noise would get very loud and eventually the amp would shut down.
The "mute" relays always emit a series of rapid clicks at power on and shutdown.
When powered on, the unit sometimes stays on indefinitely. Sometimes the MUTE relays start clicking very rapidly and then the unit shuts down.
Sometimes it just refuses to power up altogether.
Sometimes I have a "check speaker wire" at the display.
I have tried disconnecting the main rails going into the amps S1L+ an S1L- and it still happens. I do not measure any DC at the output terminals - but that's expected with the main rails disconnected I guess.
I have scoped the rails and I believe the main processor is instructing the relays to do what I hear - in other words, the rails are stable-ish, the relays click rapidly because this is what comes from the main processor.
Any ideas on what this could be? I do not know the logic behind the processor so if my mute signals are triggered, I am not sure why that happens.
The fact that the amp sometimes stays on indefinitely, makes me think of a bad joint to be honest.
Here is a link of a video where you can hear the issue: https://youtu.be/v-JHgep2NzA
First time I turn it on, you can hear the relays clicking rapidly but then it stays on. The same when I turn it off.
Second time, I turn it on and after a few seconds the MUTE relays start to sing until I then switch it off myself.
Any ideas very much appreciated!
Thanks!
I've acquired a faulty Onkyo HT-R390 receiver - it's very low spec with "monolitic" amplifier ICs. It's mostly an exercise for me.
It would not power up (It would shut down immediately).
I believe I found one of those monolitic chips shorted so I ordered a new one.
However, the amp still has trouble powering up.
It's a bit weird. I know the amp works - I plugged a source and a speaker and I had sound from both channels but at least one channel had some noise in the background and if I wiggled the input RCA the noise would get very loud and eventually the amp would shut down.
The "mute" relays always emit a series of rapid clicks at power on and shutdown.
When powered on, the unit sometimes stays on indefinitely. Sometimes the MUTE relays start clicking very rapidly and then the unit shuts down.
Sometimes it just refuses to power up altogether.
Sometimes I have a "check speaker wire" at the display.
I have tried disconnecting the main rails going into the amps S1L+ an S1L- and it still happens. I do not measure any DC at the output terminals - but that's expected with the main rails disconnected I guess.
I have scoped the rails and I believe the main processor is instructing the relays to do what I hear - in other words, the rails are stable-ish, the relays click rapidly because this is what comes from the main processor.
Any ideas on what this could be? I do not know the logic behind the processor so if my mute signals are triggered, I am not sure why that happens.
The fact that the amp sometimes stays on indefinitely, makes me think of a bad joint to be honest.
Here is a link of a video where you can hear the issue: https://youtu.be/v-JHgep2NzA
First time I turn it on, you can hear the relays clicking rapidly but then it stays on. The same when I turn it off.
Second time, I turn it on and after a few seconds the MUTE relays start to sing until I then switch it off myself.
Any ideas very much appreciated!
Thanks!
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