820-2936 missing U5400

MDY

New member
820-2936 missing U5400
And missing all pads to solder a new U5400
Can this board works without U5400? What is its role?
 

dukefawks

Administrator
Connect pin 1 of R5403 to pin 1 of R5413. This is cheating but I think it should pass ASD like that. U5400 is the current sensor for the CPU rails.
Not sure if this will work but run ASD after you did this.
 

MDY

New member
Problem is this board has no video now. Not lvds and not external monitor. USB mouse is active (light). So I dont know where to start.

What I checked is in LVDS connector I have PP3V3_LCDVDD_SW_F at 3.3V
 

dukefawks

Administrator
If PP3V3_LCDVDD_SW_F is high there must be an image, check again. Use a flashlight to check.

What is voltage on PPVOUT_SW_LCDBKLT?
 

MDY

New member
You are right. It works with another screen. With his screen no video... meybe lcd cable
With another screen it has video but no backlight. I did a reflow to LP8550 and now backlight is ok. Should I replace it or this is ok
 

MDY

New member
Ok, now I need to replace the screen. It is true all screen A1278 from 2008 to 2012 are the same?
 
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