Onkyo TX-NR807 digital low volume

[frankusb]

Hi,

I have an ebay TX-NR807 that has the following characteristics. Analog sources that are played in direct or pure audio work normally on main L/R speakers and Zone 2 (which is analog only). If I use any digital playback mode or digital source, the main L/R speakers play, but at a greatly reduced volume. It might be slightly distorted. Full volume on the unit provides a moderate listening level for digital sources or analog sources that are digitally processed.

The service manual is here.

The HDMI board has been upgraded I assume by Onkyo as the DSP is a new one. Network and HDMI output from the setup menu work correctly. I have performed a factory reset. The unit shows 7600 hours of use but since the HDMI board has been replaced, I'm not sure how accurate that is or if the hours are stored on the HDMI board.

Looking at the schematic one thing I would like to check is the DAC voltage rails. But I am having a hard time finding where the +15VA and -15VA is generated.

Can someone point me to where these rails are being generated? Or is there any other area I should be looking at first?

Thanks!

[R_J]

Re: Onkyo TX-NR807 digital low volume

It looks like they come from (page 8) Q5671 [79M15] & Q5670 [78M15] Those regulators are supplied from the +&- 22 supplied by D5601 Bridge

[frankusb]

Re: Onkyo TX-NR807 digital low volume

Thanks, sorry I missed that.

I measured the voltage on C1650 and C1651 on U003. Granted I measured the wrong leg on C1650 before disassembly. But I found 0 volts on C1651. I also measured the +15/-15 volt rails on U0031, the board next to U003 and the rails are fine.

What I found is that the P1008B connector was either damaged when I removed U003 or that's why there was no voltage on C1651 to start with.

But I'm having trouble locating a place I can purchase a replacement. I believe I need imsa-9142b-20a. It's a 20 pin female connector that I need to replace.

Any idea where I can source these?

[R_J]

Re: Onkyo TX-NR807 digital low volume

I don't know, post a good picture, maybe its used on something else, also check if there might be a mfg name on it or a number

[frankusb]

Re: Onkyo TX-NR807 digital low volume

Here are both sides.

[R_J]

Re: Onkyo TX-NR807 digital low volume

Looks like someone has taken the female connector apart once, I don't know where you would find that plug, you could carefully remove the cover and straighten the female contacts, then replace the plastic cover? That might work, maybe someone here might have a scrapped board with that connector
They look similar to Eurocard Connector

[frankusb]

Re: Onkyo TX-NR807 digital low volume

Thanks, I tried but the assembly was single use. So I wired it, not the most elegant or versatile but I don't intend to take it apart often. Initial testing is good, front L/R are working at normal volumes in all modes now.

[Longbow]

Re: Onkyo TX-NR807 digital low volume

This makes no sense to me. Your main symptom was low volume through the digital processing chain. It is unclear whether you confirmed a missing voltage, or simply measured the wrong point. There would be no output at all if you were missing a rail on the digital board, so I doubt if you found the real problem. There might have been a loose wire on your connector, but if so you got lucky. In the same circumstances, which might re-occur, a full reset would be the first step to make sure all the inputs are set back to normal.

[frankusb]

Re: Onkyo TX-NR807 digital low volume

The only thing that does not make sense to me is how the connector ended up being damaged. I would assume to apply enough force to break the wires in the female connector that the male connector would show signs of the abuse.

I confirmed a missing voltage of +15V on C1651. I measured the wrong leg on C1650 so did not confirm that voltage missing before disassembly. But once I removed the DAC board, I was able to probe the female connector and verify which signals were still connected. I was missing both the +15 and -15 rails. If I recall correctly the +12V rail was present (it's on 2 pins) and both analog and digital grounds were present.

The volume needed to be turned all the way up to hear a quiet signal when the digital path was taken.

I did perform a full reset before disassembly and I also had to after reassembly.

As for other problems, I have not found any. I installed the receiver Sunday and have used it for probably 4 hours now without issue exclusively through the digital path.