Yamaha RX-V459 receiver/amplifier does not power on

[HellasTechn]

Dear friends

Good day !

A friend of mine brought in a YAMAHA RX-V459 AV Receiver - amplifier.

He says that it just stopped working.

When i plug it in and press power button i can hear the input relay clicking and a few sec's later it clicks again and the device stays off.

I remember exactly the same symptom on an other yamaha audio amplifier and the problem was a large poly cap at the input and also the jack connecting the psu pcb with the rest circuit. but this is not the cace with RX-V459. i tried to find something on the net but came up empty. I will look for the service mnual to study the psu circuit to see what drives the relay...

Any suggestions ?

 

[Gryd3]

Any suggestions ?

First and foremost, pop it open and look for obvious signs of damage.
Check for loose or damaged wires, bulged or leaking caps, and discoloration.
If the board is laid out in an accessible way, you may very well be able to trace the lines from the relay to determine how it's driven...

 

[KrisBlueNZ]

You can get a version of the service manual from elektrotanya at http://elektrotanya.com/yamaha_dsp-ax459_htr-5935_htr-5940_rx-v459.pdf/download.html.

There are several speaker relays, and they are all controlled by the microcontroller in the DSP section. There could be a number of reasons why that microcontroller decides to disable the speakers.

As well as what Gryd3 suggested, check under the board for dry joints, and upload some photos of both sides of the main board.

 

[HellasTechn]

First and foremost, pop it open and look for obvious signs of damage.
Check for loose or damaged wires, bulged or leaking caps, and discoloration.
If the board is laid out in an accessible way, you may very well be able to trace the lines from the relay to determine how it's driven...

Yes that is always the first thing i do. like i mentiond in my first post it is not a capacitor issue at least as far as i can see with naked eye.

I have checked a transistor that it's base is connected on the relay coil but it is okay.

I guess it could be the ic that controls the relay

i will get back to you with photos.

 

[HellasTechn]

There are several speaker relays, and they are all controlled by the microcontroller in the DSP section. There could be a number of reasons why that microcontroller decides to disable the speakers..

The relay that click "on" and right after "of" is not one of the speakers relays.
It is located on "operation 4 pcb if memmory serves well" where mains input is connected and the transformer feeds voltage to the rest of the circuits.

hmmm....

 

[Gryd3]

Yes that is always the first thing i do. like i mentiond in my first post it is not a capacitor issue at least as far as i can see with naked eye.

I have checked a transistor that it's base is connected on the relay coil but it is okay.

I was unsure if you just googled it, or actually opened it. Good to hear you took a look.

There is a fault in there, the tricky part is finding it as it sounds like the microcontroller responsible for the system is turning the relay back off...
As Kris had suggested, snap a couple pics, and take a close look at the solder joints (especially around larger/heavier components) that may be fractured or dry.

 

[HellasTechn]

Tomorrow i will take a few photos and get back to you. i will also look for the controller ic and see if i can find one and replace it.
Bad thing is that finding such parts here in Greece it is not easy. Most likely i will have to order it online and wait about a month.

 

[Gryd3]

Tomorrow i will take a few photos and get back to you. i will also look for the controller ic and see if i can find one and replace it.
Bad thing is that finding such parts here in Greece it is not easy. Most likely i will have to order it online and wait about a month.

Most likely, controller ICs are hard to source, or require firmware... let's hope that's not the culprit and see if perhaps a supporting component or sub-circuit has failed causing it to shutdown the amp to help preserve itself.

*faster than Kris! (Just need more skills to out-think and out-type him)

 

[KrisBlueNZ]

Don't bother looking for that device online - it looks like it's programmed by the manufacturer. In any case it's unlikely to be faulty; it's probably shutting down because it has detected a problem somewhere else.

Gryd3: Snap!