820-3115 not recognizing screen

2informaticos

Administrator
Staff member
AXG voltage only comes up under heavy graphics load.

As you have working board, compare readings between both boards.
 

2informaticos

Administrator
Staff member
LVDS clock signal comes from PCH; you should change it.
Did you comàre diode mode to ground readings between the boards?
 

Chuck60

Member
Ok both boards measurements are equal in diode mode and ohms. Let’s say I was gonna attempt a pch swap what size solder balls would I use ?
 

Chuck60

Member
Oh I’m using a bga stencil Or what I think is a bga stencil that just lines up. I will look for the Correct stencil and right down the size or just use solder paste :) thanks
 

piernov

Moderator
Staff member
Balls should be 0.3mm. Ball size should indeed be marked on the stencil, you can't use a random stencil, only stencil for 6/7 series mobile chipset will line up.
If you have a decent BGA rework station you can buy pre-balled PCH and solder it lead-free. Will save your time and sanity.
 

Chuck60

Member
Hi, I just wanted to recap. I wanted to find the exact reason why I wasn’t getting all my signals for lvds. I’m not sure this is correct but on pin 458 of u1800 I have a dead 0.00v short I removed (R2465, R2460, C2465,C2466,C7781,u7800) on this line and on u7800 Pin 1 (PP1V05_S0_PCH_VCCADPLL)
I still have a dead short. I’m guessing it’s directly from PCH. So I’ll go ahead and replace :) thank you 2informatico and piernov
 
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Chuck60

Member
Hi, @piernov thank you for you help :( honestly I’m gonna Use a modified digital cook top So I’m guessing it’s not classified as “decent” and I have a hozan bga hot air from the top. I also have a Quick 861On my desk. I see you’ve already answered my question About buying a new PCH above so I’ll buy it new :) Let’s see how this goes wish me luck that I’ll pull out a miracle
 
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