asus g752vs strange problem

[myth77]

So, laptop was with dead cpu, replaced. Now everything works except i have problems with audio. The problem is related with long audio cable that from one side is plugged in the motherboard and on the other side is connected to audio daughter board that goes on the top of the laptop(behind screen). The symptoms are:

1. In bios everything ok (with long audio cable on connector j3701 connected or not),
2. With windows installed everything ok if long audio cable on connector j3701 is not connected,
3. With windows installed and long audio cable on connector j3701 is connected i will have symptoms of loading windows then freezes everything, or only asus logo with slow turning wheel. So basically if audio cable connected the board is not working.
5. if its not connected then everything is fine and i can play games...and so on.

What i did so far: checked capacitors for short, replaced ALC668, replaced u3701 and u3901 audio amp chips, replaced all ferrite bead in that area (even though they were good). Checked j3701 connector for shorts but everything is ok. Ordered another long audio cable on connector j3701 but same, ordered another audio daughter board but the same.
When i measure heat in that area when long audio cable is connected, it is very hot...it goes to 55 C. The most heated area is around ferrite bead and audio amp chips.

And the funniest part is if I stretch the long audio cable the windows will load normally and if i connect the audio daughter board at the end the sound is fine. But the moment i release audio cable in normal state (not stretched) the symptoms start again. Thats why i bought the second audio cable but symptoms are the same.

I dont understand what is happening...i can make video of this really weird problem...anybody have any idea?

schematic link: https://www.badcaps.net/forum/showth...hlight=g752vsk

[mon2]

Re: asus g752vs strange problem

Connect the audio fpc cable. Disconnect the audio board that is on the other side of the cable.

Does the ic still heat up?

Post pics of this cable so we can review the pin pitch. Be sure that pin #1 on the cable mates to pin #1 on the audio board.

[myth77]

Re: asus g752vs strange problem

Connect the audio fpc cable. Disconnect the audio board that is on the other side of the cable.

Does the ic still heat up?

yes

Post pics of this cable so we can review the pin pitch. Be sure that pin #1 on the cable mates to pin #1 on the audio board.

everything is matching...i will try to make video later..

[mon2]

Re: asus g752vs strange problem

If you remove this floating cable, the ic will not heat up?

If true, the cable contacts are of the wrong pitch for this connector.

Post pics of the contacts and place it beside the connector on the logic board.

The contacts on the cable must be shorting the audio outputs.

[myth77]

Re: asus g752vs strange problem

ok, i posted video on yotube... link https://youtu.be/TuwsnvpFhTQ
As you can see from the first part when audio cable not connected the laptop is working fine.
When i connect it, it will not boot and commonly it will freeze.
When i connect it and strach cable it will work and i can even have sound on it!?

Can someone explain what is this weird shee. going on...never seen anything like it.

I posted here a picture of the connector, so you can see it is ok. On the first i also suspected a bad audio cable but i ordered new, but same problem. There is no short between pins.

[mon2]

Re: asus g752vs strange problem

Have a thought that you switching power supplies nearby. This coiled up wire is acting like an inductor and the switching energy is being transferred back to the audio circuit. When you stretch the wire, the coil is effectively broken and no longer acts like an inductor.