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820-00840-A Not powering on, voltage fluctuates.

E

Epoch

New member
Hello! I have an 820-00840-A that does not power on. The amp meter reads 20v but the amps loop from .00a to .50a. I'm not sure of the history of this motherboard but it does look like some rework was done around u7000.

PPBUS_G3H: Starts at 13.09V and holds for about 5 seconds then jumps around really fast to 12v 11v 13v 11v 8v then to 13.09v then that cycle repeats
PP5V_S5: 0.2V-5.1V Loops
PP3V3_G3H: 3.4V
PP3V3_S5: 0v-3.3V Loops
PPDCIN_G3H: 19V
P5VS4_EN: 0v-3.2v Loops
 
2informaticos

2informaticos

Administrator
Staff member
First of all, welcome to the forum!

Did you test the board alone on the desk?
Remove any cable, including battery and trackpad.
 
E

Epoch

New member
Hello, Thankyou!
Yes I had the mother board completed removed from the device with nothing else plugged in.
 
Last edited:
E

Epoch

New member
I wanted to report that the motherboard does turn on now and all the jumpy readings I was getting have disappeared for now. I'm not sure why it's working now because all I did so far was test L7030 In diode mode to ground and got 0.466v on both sides. Before moving on to the next coil I wanted to check PPBUS_G3H again noticed it was at 13.1v and it was steady. I began to check the other rails that were jumpy from my original response and noticed they were steady as well. So with all my rails steady I put the laptop back together turned the machine on and it powered right up!
 
E

Epoch

New member
So far things looking good. Battery Charges, Wifi connects, Audio sounds good, Sleep mode works. Going to leave it on overnight and check in the morning to make sure everything stays working. We'll see!
 
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