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A1706 820-00923-A no boot

H

hgoncalves

Active member
Hi,

I have an A1706 820-00923-A, that after replacing de display, it stooped working. Already replaced with a known good lcd, and ot doesn't power on.

I has 19.5V on ampmeter, and consumes around 0.55 A to 0.86 A (only board. Full assembled and with battery it gets to around 2A). CPU gets hot, but it seams to don't have CPU activity, because the caps lock doesn't turn on, and doesn't show any image on external monitor.
Can't see any damage components on board.

PPVCC_S0_CPU = 1V
PPVCC_CPU PH1/2 = 1V
PPDCPRTC_PCH= 1.6V
PPVCCGT = 0V

What should i check?

Can you help?
 
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H

hgoncalves

Active member
That is my problem. I can't see anything wrong... maybe it was static electricity or something like that. Do you have any idea of what / where should I start taking measures? I already spend hours looking and I really can't see any knocked off components...
 
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2informaticos

2informaticos

Administrator
Staff member
You should note some changes on the VCC_S0_CPU.
If starts and stays at 1V, board doesn't really boot.
You can compare its behavior with known good working board.

PLT_RESET_L comes high?
Test the board alone on the desk; no device connected.
 
H

hgoncalves

Active member
Hi, thank you.

Full assembled it responds to the SMC Reset on the keyboard and the fans start spining, but it doesn't do anything else.

With board alone i get:
VCC_S0_CPU oscillates between 1.08V and 1.09V and doesn't drop to 0V.
PLT_RESET_L = 3.3V

Already tried SMC bypass without success.

Can you help?
 
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2informaticos

2informaticos

Administrator
Staff member
Damage induced when the LCD assembly was changed.
Should be mechanical problem, like broken trace, or knocked off components.
 
H

hgoncalves

Active member
Thank you!.
I already spend hours looking on the microscope, and I can't see anything wrong. Can I measure something to figure out the area that i should look deeper?
Is there any way to narow down the area?
I really can't see nothing wrong on the board and don't know what else to do...
 
H

hgoncalves

Active member
Thanks.
After install the Clean ME, it has the same behavier (doesn't boot), but now one of the fans boots at full rpm and the other fan is stoped. VCC_S0_CPU is at 1.08V steady...
What else should i do?
 
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H

hgoncalves

Active member
Hi,
After installing the original BIOS, the laptop has similar, btut different, behavier (no fan spin and 1.08V on VCC_S0_CPU )
 
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D

Dusten04

Member
Im having the exact same issue right now. (Ship in repair)

My client stated that he did a screen replacement. After screen replacement, he stated touchbar did not work. So when he was disconnecting flexes, he heard a chime, at which point he realized that the battery was still connected. Very similar behavior. I get fan spin when CPU gets hot enough, board seems to be booting, but no internal or external image. I am getting 1v06 on VCC_S0_CPU, and then it drops to about .640v after about 10 seconds or so. PLT_RESET_L is a steady 3v3
 
H

hgoncalves

Active member
Hi,
Who should have USB activity ? Me or Dusten04?
I don't have any USB activity .
After installing the original BIOS, the laptop has similar, but different, behavier (no fan spin and 1.08V steady on VCC_S0_CPU). Do you have any other idea about what can be wrong in my case?
 
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