VSX-925-K flashing PQLS light, turns off immediately

Question

Pioneer VSX-821-K

This receiver is Bluetooth Ready, has 110 Watts x 5 Direct Energy Amplification and is iPad / iPhone Certified with supplied cable

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Jean-Sébastien Guay @skylark13

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게시일: 2021년 11월 12일

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VSX-925-K flashing PQLS light, turns off immediately

Hello,

I could not find the Pioneer VSX-925-K receiver in the device list.

The PQLS light flashes when the unit is turned off, and if I press the power button to turn it on, it turns back off by itself after about a second.

I have found the service manual for the VSX-1020-K which according to some info I’ve found is very similar to the 925. It says in the “error indications” section that a flashing PQLS light means “"Abnormality DC voltage of the Digital power supply" detection”.

In the “diagnosis flowchart” section, I have done the “Step 2: Power supply” flowchart steps. All voltages the flowchart had me check were OK.

Where do I go from there? Are there more checks I can do to diagnose the specific problem, and possibly repair it? I have a multimeter, a soldering iron and some experience soldering, so I should be able to repair the problem if I knew what it was. I also have an oscilloscope (compact 1-channel one) but no experience actually using it, so if I need to use that to go further I’d need a bit more hand-holding.

Thanks in advance,

J-S

Here are pictures of the unit:

The Digital Main Assy board (with the HDMI ports, at the top):

The Main Assy (power board, at the bottom):

The main transformer:

Service Manual for VSX-1020 which is very similar to VSX-925, and the manual is much more detailed than the one for the 925:

Pioneer Vsx 1020 K 1025 K Sm

CP11 in the service manual

CP11 in my unit

O/L Detect wire disconnected

Edit 2021-12-21

Area around X361

Area around X362

Wear around screw holes

Edit 2021-12-24

Cold solder joints on HDMI ports

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@skylark13 you have tried a reset? Remember that the flashing PQLS indicates DC voltage on a speaker output line. Most commonly caused by failed transistors. Have you checked for obviously damaged components like failed capacitors, burnt MOSFETS etc?

oldturkey03 의 2021년 11월 12일

Thanks for your reply @oldturkey03 .

I do not know how to do a reset on this unit. I can't find the info in the service manual I have. Do you know how to do it?

I have checked all the capacitors, none are bulging or leaking. I don't know what a MOSFET is, what does it look like?

Thanks again!

Jean-Sébastien Guay 의 2021년 11월 13일

@skylark13 should be something like press and hold the "Multi-Zone On/Off" and the "Tune Down" (or Preset Down) buttons for about 4-5 seconds and see if it power on. Post some good pictures of your boards with your QUESTION. That way we can check for any obvious damage.

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oldturkey03 의 2021년 11월 13일

@oldturkey03 I have tried holding Multi-Zone On/Off with either Tune Down or Preset Down for over 10 seconds, and nothing happens. Note that I do this with the receiver turned off, because it does not stay on long enough for me to be able to do it when it's on...

I have edited my initial post with pictures of the boards where I think the problem should be (hopefully they're good enough). If there's another board you'd like a picture of, just let me know. There are 2 fuses on the bottom board (the brown one), I have tested them and they are both good.

Thanks!

Jean-Sébastien Guay 의 2021년 11월 13일

@skylark13 boards look ok with nothing really obvious but hard to make out since the boards are mounted. CP11 would be of interest. Check the schematic and see if you can determine that pathway and check those components. I suspect a bad power transistor.

oldturkey03 의 2021년 11월 14일

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@skylark13 you have tried a reset? Remember that the flashing PQLS indicates DC voltage on a speaker output line. Most commonly caused by failed transistors. Have you checked for obviously damaged components like failed capacitors, burnt MOSFETS etc? — oldturkey03
Thanks for your reply @oldturkey03 .

I do not know how to do a reset on this unit. I can't find the info in the service manual I have. Do you know how to do it?

I have checked all the capacitors, none are bulging or leaking. I don't know what a MOSFET is, what does it look like?

Thanks again! — Jean-Sébastien Guay
@skylark13 should be something like press and hold the "Multi-Zone On/Off" and the "Tune Down" (or Preset Down) buttons for about 4-5 seconds and see if it power on. Post some good pictures of your boards with your QUESTION. That way we can check for any obvious damage.

기존 질문에 이미지 추가하기 — oldturkey03
@oldturkey03 I have tried holding Multi-Zone On/Off with either Tune Down or Preset Down for over 10 seconds, and nothing happens. Note that I do this with the receiver turned off, because it does not stay on long enough for me to be able to do it when it's on...

I have edited my initial post with pictures of the boards where I think the problem should be (hopefully they're good enough). If there's another board you'd like a picture of, just let me know. There are 2 fuses on the bottom board (the brown one), I have tested them and they are both good.

Thanks! — Jean-Sébastien Guay
@skylark13 boards look ok with nothing really obvious but hard to make out since the boards are mounted. CP11 would be of interest. Check the schematic and see if you can determine that pathway and check those components. I suspect a bad power transistor. — oldturkey03

oldturkey03 @oldturkey03 평판: 783.2k 1.1k 893 2.3k · Answer 1 · 2021-11-14T08:30:32-07:00

oldturkey03 @oldturkey03

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@skylark13 this is not an answer just a way to attach the right SM for your receiver. I prefer to have the right schematics so there should be no guessing. CP11 connector/cable is the one that we need to find. #8 connector is the one that shuts it off based on the OL condition. Disconnecting the OL circuit should get your receiver to turn on but it will not resolve the OL (OverLoad) condition.

Pioneer VSX 30 31 925

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@oldturkey03 I have tried to disconnect wire #8 on connector CP11 (clearly labeled O/L Detect on the board) and there is no change in behavior. The PQLS light still flashes, and the unit still turns off about a second after having pressed the power button to turn it on.

I will try to see what connects to that wire and see if the components look good there, but if there is anything else you can think of that I could try to diagnose the problem let me know.

I have updated the OP with photos of CP11 and also attached the service manual of the VSX-1020 which is pretty much identical to my unit but that SM contains a lot more information (and the picture I used to locate CP11).

Jean-Sébastien Guay 의 2021년 11월 14일

@oldturkey03 Do you have any other ideas as to how I could diagnose the problem? Do I need to do something other than disconnect wire #8 on connector CP11 to disable the OL circuit?

Jean-Sébastien Guay 의 2021년 11월 17일

@skylark13 sorry, got a bit sidetracked last couple of weeks. Let me pick this back up and check what else we should look at.

oldturkey03 의 2021년 11월 20일

@oldturkey03 No problem, let me know if you spot anything else (or if there's another way to disable the OL Detect to test that). Thanks in advance!

Jean-Sébastien Guay 의 2021년 11월 27일

@oldturkey03 Sorry to message you again, but do you have any ideas? I've had the receiver disassembled on my desk for a few weeks now, and if we can't find the problem I'll just sell it for parts I guess. Thanks in advance.

Jean-Sébastien Guay 의 2021년 12월 8일

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Pioneer VSX-821-K

VSX-925-K flashing PQLS light, turns off immediately

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