820-2915 short on pp3v42

[Chuck60]

Hi, I have a board that has a short on pp3v42_g3h line it’s .14v in diode mode
This is what I have done so far I remove the isl, replaced both usb controllers that were shorting 5v line. I still have a short on 3.42
I have .14v in between r5070 Pin1 and Pin 2 r5000 Where would be a good starting point
Gpu isn’t in short and cpu is measuring normal. Honestly I think it might be the gmux but I was avoiding that soo how difficult is it to replace gmux. I only have one gmux on a parts board ? What would be the next move ?

 

[2informaticos]

There is high ohm value and may not heat anything injecting voltage.
But you can try, maybe some chip enters into thermal avalanche; good IR cam can help.

Did you clean J6955?
Did you remove U7000 before SMC?
I don't see GMUX directly connected in boardview.

First lift L6995 one pin and see where the low value remains.

 

[Chuck60]

The gmux was getting really hot. I removed the u7000 first. then I removed U5010 but I Have not removed the smc.
J6955 has no visible damage. But I will further inspect it. I will lift on leg of L6995 and see on which pin it remains on.
thank you for your help

 

[Chuck60]

I removed L6995 and on Diode mode pin 1 .595v on pin 2 .14v I removed u4650 cleaned and tested still have .14v on pin 2 at L6995 inspected j6955 it’s in pristine condition

 

[2informaticos]

3V42 rail should have .300 aprox in diode mode (red probe at ground).
But do you get any voltage there?

 

[Chuck60]

Well since I have L6995, isl6295,U5010 still of the board I get nothing on pin 1 of L6995
At ppvin_g3h_p3v42g3h =16.54v and 16.54 at
(r6995 which is also ppvin_g3h_p3v42g3h.
3.7v at Pin2 p3v42g3h_ton)
c6991 pin 1 3.72 p3v42g3h_fb = 3.7v

 

[2informaticos]

Do you mean these components are not soldered?
No reason to check voltages then...

 

[Chuck60]

No they aren’t soldered. I testing chips on the board I remove the 5v,3.3v driver and I still have .14v So I’m gonna see if the audio driver is pulling the line down. I have a feeling it’s one of these chips. Do you think I’m on the right track?

 

[2informaticos]

This kind of issue is not easy to solve...

 

[Chuck60]

Ok I’ll do my best it’s a learning process for me thank you for your help

 

[2informaticos]

But you should put back the good components and test the board.
If the board starts, an issue with some device connected to 3V42, can point you in the right direction.

0.140 is not as low value to block 3V42 power supply; worth to try...

 

[Chuck60]

Ok I’m revisiting this board. I have put everything back and same issue the pch is blazing hot. I don’t know why I put “gmux” in the earlier comments but it’s The platform controller hub u1800. I guess my question is How difficult is it to change pch on this board ? Never removed one but I do have a bunch of different stencils So I’ll just try to match it with one. How hard would you say is this task? I don’t have a pre heater but I do have two hot air stations set for bottom and top heating. Thanks again for your help

 

[2informaticos]

I do not recommend to continue without a decent rework station.
Just in case, gently scratch around the PCH to leave a mark which helps you re-align the chip.