Z333 Speakers not working - No sound

Hi,

I have the Logitech Z333 speaker system which has worked mostly fine for the time I've had it.

Recently I tried to use it and found that there was no sound at all coming from any of the speakers (sub and side speakers). I've done the usual basic checks with cabling etc and its definitely nothing wrong with the way I've set it up.

The volume control unit still has the green power light come on when I switch it on. No sound whatsoever comes from the speakers though.

My suspicion is that a component inside has died, but I'm not sure how to locate it. I have a feeling it could be the part of the circuit that supplies power to the audio units as no power seems to be reaching them when turned on.

For anyone unfamiliar with this system, there are 3 separate PCBs, one in the volume control unit (switch on functionality and volume control), power supply PCB from mains, and an audio PCB which I believe handles all the audio signal components.

I've started checking individual ICs on board and voltages etc. When the power switch is off, the enable line has 4.9V on it but when switched on, this drops to 4.45V. Following this voltage round, it comes to this IC which I can't find the datasheet for:

Block Image

Thanks

This thread has photos of the volume control unit: No sound from speaker

Otherwise, these videos do a full break down of the system:

https://www.youtube.com/watch?v=QocJelZ6...

https://www.youtube.com/watch?v=8uFNXWf0...

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@elliotp890 it will help if you post pictures from your boards. This does sound like a power issue so we really would need to see those. Adding images to an existing question

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Hi @oldturkey03

Admittedly I was being lazy when I posted this originally!

I've started checking components and ICs on the audio PCB, and following signals + voltages through on each net to check everything is going where it should be. There's one IC though which I can't find the datasheet for anywhere, I've added a photo to the post. Do you have any ideas what it may be?

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