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Old 07-21-2019, 01:52 PM   #21
petehall347
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Default Re: Receiver Onkyo HT-R570 no sound .

is tape switch set to source ?
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Old 07-21-2019, 03:54 PM   #22
RogerioBarbosa
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Default Re: Receiver Onkyo HT-R570 no sound .

Yes, there is a MUTE button on the remote, but it is not changing this line that is always triggering the transistor Q5600 at part5: G5. I'm confused because there is a line called MUTE, which I suppose would be the MUTE line.
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Old 07-21-2019, 05:38 PM   #23
petehall347
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Default Re: Receiver Onkyo HT-R570 no sound .

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Originally Posted by RogerioBarbosa View Post
Thank you,Yes, it has speaker test/setup feature, but no sound during the test.
I think the receiver is muting, because there is a protection circuit that doesn't allow the sound to reach the power amplifiers in case of something goes wrong. I measured the *V at the base of one of these transistors, and it is positive(2,5V), indicating that it is conducting and ground the power amplifier imput signal , after the pre-anplifier.(Q5600 at part5:G5).The problem now is: Why this V at the transistor base? There is a signal called AMUT, I don´t know exatly it means, but could be this signal that is doing the transistor ground the signal that goes to the power amplifiers.
i would cut the base and see what happens . or i might separate pre from main then inject signal to main . well only if main amp is testing ok current and offset .
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Old 07-21-2019, 07:12 PM   #24
R_J
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Default Re: Receiver Onkyo HT-R570 no sound .

Check the voltage on POFF (page21) These amps do mute while powering on or off, that might have something to do with it?
Just to be sure you can check the amp offset voltage on JL6600B, all pins should be close to 0 volts

Last edited by R_J; 07-21-2019 at 07:27 PM..
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Old 07-21-2019, 07:21 PM   #25
RogerioBarbosa
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Default Re: Receiver Onkyo HT-R570 no sound .

I opened the AMUT line and the V at the base of the Q5600 transistor changed from 2.5V to -15V, so the transistor no longer landed the signal, but the sound did not appear.
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Last edited by RogerioBarbosa; 07-21-2019 at 07:28 PM.. Reason: made a mistake
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Old 07-21-2019, 07:36 PM   #26
R_J
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Default Re: Receiver Onkyo HT-R570 no sound .

This AMUTE is likely a control line that the microprocessor uses to mute the audio when sources are switched etc. so you don't get a pop in the audio when you switch sources. That would be my guess since I don't know the microprocessor's program code.
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Old 07-21-2019, 08:37 PM   #27
RogerioBarbosa
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Default Re: Receiver Onkyo HT-R570 no sound .

Ok, tank you about AMUTE. I injected audio into the CD input and placed the oscilloscope in the Q5600 collector and got no signal.I know Q5600 is not driving because his base is with -15V
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Old 07-21-2019, 08:54 PM   #28
R_J
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Default Re: Receiver Onkyo HT-R570 no sound .

The conrtrol line must be open and the R6681 is the pullup to the -15 volt line, so AMUT must need to be taken low to un-mute the amp, or in this case taken to +5volts
Check the voltage on Q752, and Q751, then check Q703 regulator, It seems to supply Q752 via D702 and R711(47Ω)
I think Q793 is a 5.6 volt regulator, it is supplied by the +10VS (from the standby circuit)

Last edited by R_J; 07-21-2019 at 09:26 PM..
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