PC front panel audio/usb panel circuit

[Agony]

So new case - and annoying front panel noise.
Wiring and mobo itself ok - and as always its the front panel itself:


The  headphone/mic jack ground is same with the USB - no wonder there is noise.


So in theory i could phsically isolate the jacks from usb. EAch jack shares common ground and has 2 conenctiosn for left/right.

But as a result with it separated from the usb fails - the sound is quiet and weak (as if it somehow depends of usb GND instead?) any ideas?

[hammil]

It's all the same ground system. The entire PC will be mains-earth referenced. Do you have an oscilloscope? Do some measurements at various points along the signal path - from the motherboard to the jack - under different conditions.

[Agony]

unfortunately no osc available so no way to really probe anything.

Tho the audio  jack  should have separate  gnd pin - why would it  connect it through the usb cable.

Unless they used soem off the shelf common parts and just jacked the connector to it.

The 3 pins right above the large connector for each jack dont look like they are for just structual. gonna crack it open again and see the pins on the mobo side connector.

[c4757p]

That board looks very familiar... I swear my PC's case has the same little board and I had to replace the piece of crap USB jacks that were on it. And I have some horrifically nasty noise as well. Pathetic... I never bothered to do anything with it - just connected to the rear port instead. But I do have a scope or three. Maybe I'll have a look at it for you later.

[Agony]

yeah looks liek a standard bpard - it even has the  ground 'connections aroudn screw hoels - even tho the screw  attach to the  plastic case.

The HD pinout standard has a  gnd pin. So i dont see why would it be  linekd to the USB GND.

Just dont want to  jack it out again (they decided to hide it behind front panel,  closed with 6 screws -_- in annoyign hard to reach spots) - specially since i get my solder station back in a few days i wouldbt be able to do much rewireing.

Yeah back works - but if you use headsphones and speakers.. .one jack on back isnt enough.

[c4757p]

Yeah back works - but if you use headsphones and speakers.. .one jack on back isnt enough.

Luckily for me, my speakers have a wanky little control pod that sits on the desk and has a headphone jack. Maybe you could build something like that temporarily?