Pioneer VSX-323-K not powering up

[Dr.Wily]

Hello EEV community !

I have a problem with my old AVR companion Pioneer VSX-323-K.

it no longer turn on. When I press power button, the power supply board relay clicks then powers off straight (the far right end of the display lights up very briefly then off)

- pressing the power button generates a click caused by the relay on the standby PCB
- a long press on this same power button, turns on the amp, which goes into protection after a few seconds by turning off and flashing the red "HDMI" LED
- by performing a reset (power key + "advanced surround" for more than 3 seconds) we return to the original problem which is that the amp does not turn on.

By disconnecting the processor card (HDMI + DSP) the amp turns on and stays on. But no sound is emitted, even with the tuner. Shorting the relay on the standby PCB card will force the amp to turn on and go into protection (HDMI LED flashing).

this issue is not directly related to the amplifier card. I have checked absolutely everything in the amplifier and power supply. No component is burnt out or weakened.

Do you know where to look? I have no idea.

Thanks ! 

[David_AVD]

Sometimes the small transistors that detect excess amplifier current go leaky and trigger the over current protection. I have seen this with Yamaha and Denon amplifiers before.

It will likely be a small SMD transistor wired to one emitter resistor in each channel. There is one transistor per channel. Sometimes replacing them all is the easiest / fastest way to proceed.

The service manual should say if the flashing LED is an over current protection. If you can't get it into diagnostic mode, it's often an over current fault.

[Dr.Wily]

Hey, tanks for your help ! 

The service manual should say if the flashing LED is an over current protection.

Yes, but there no over current. All voltage are good and the AVR stay on when the HDMI card is removed. The chip who manage protection circuitry and check over current or others is on another PCB.

Today, I reflowed some solders on HDMI card and the amp stay on and produce sound. But for powering up I must push the button more than 2 seconds otherwise the amp refuse to powering up and the power supply board relay clicks then powers off straight.

Now the amp stay on but there still an issue somewhere who prevent  the amp to powering up normally.

If you can't get it into diagnostic mode, it's often an over current fault.

I don't how to enter diagnosis mode on this model.

[David_AVD]

You can download the service manual(s) for it on the hi-fi engine site. With Pioneer, check to see if the manual you download references another manual that you'll also need to download.

[mzacharias]

Sounds like something on the HDMI board is loading down one of the power supplies.