820-00923 20V Boost, 0.55a draw. No display

[CGid]

Have an A1706 Logic board. 820-00923-A.

When plugged in system boosts to 20V drawing around 0.55a.
CPU gets hot. If left on long enough/allowed to get hot enough the fans do start spinning.

No display via the screen nor via an External monitor.

Using the tool U-SEM2, I find Pins 6,10, 31, 33, 36 and 37 are reading abnormally.

Looking at boardview pins 6 and 10 appear to be connected to the CPU. (DP_INT_HPD and LCD_IRQ_L)

As for 31 & 33 then 36 & 37. I replaced the inductors these sets of pins are connected to. On the otherside of the inductors/filters is U3900 the T1 chip.



Is the CPU or T1 chip dead? If either are dead I will say the T1 chip replacement is out of my wheelhouse at the moment.

 

[2informaticos]

Check first CPU core voltage after 15s.
If drops from 1.1V to .65V aprox, then board is booted.
Also test if you get USB activity.

Any history fault available

 

[CGid]

Check first CPU core voltage after 15s.
If drops from 1.1V to .65V aprox, then board is booted.
Also test if you get USB activity.

Any history fault available

Measuring at L7210 CPU core reads 1.05V and does not drop down at all. After roughly 30-45 seconds, maybe a minute, the amp draw drops from 0.5-0.6a down to 0.010a. There is no USB activity. Flash drive light does not turn on at all.

As for history I don't think there's much of any. System was used normally until it was brought in for not powering on. Board looks clean and untouched and there aren't any signs of liquid damage.

 

[2informaticos]

You should try known good BIOS, clean ME.

820-00923-05 OK clean.BIN

drive.google.com

BTW, write directly into reply bx, instead of clicking Reply button.
I don't see any reason to quote an entire post, visible few centimeters above.
Please, maintain forum aesthetic...

 

[CGid]

Sorry. Will do so from now on, most forums I've been on I just assume to use the reply button but I definitely understand.
I attempted the clean BIOS and Clean ME with no change for the device.

 

[2informaticos]

Tets the board alone on the desk.
Do not connect anything, apart of charger.
Check CPU core voltage if drops.

 

[CGid]

Ive only been doing testing with the board alone in the desk. I tested with and without a screen after BIOS update and no change.

 

[2informaticos]

Looks like bad CPU...

 

[CGid]

That's what I had settled on. I truly appreciate the help here.