820-01700 no power

[Kyle93]

Arrived with coffee damage. Prior repair shop cleaned the board before arriving here so this one will suck. Currently stuck at 5v. CD3215 areas look spotless

pp3v3_g3h_rtx only 0.065v, no short

ppbus_g3h is shorted. Injected 1v but nothing was warm

What to check next ???

 

[2informaticos]

On T2 machines, PPBUS_G3H is the first voltage required.
Exact ohm value for the short?
Compare with the readings on all big coils; pay atention to CPU coils.
Remove CPU heatsink and use 20A lab PSU to inject voltage, if is close to pure short.

 

[Kyle93]

Diode mode for the short is 0.002.

How much voltage should be injected? Are you suggesting lab PSU set to 20amps when injecting?

 

[Kyle93]

PPBUS_HS_CPU caps are primarly what were affected by the spill. Can these affect PPBUS_G3H?

 

[2informaticos]

By the name, I would say are in the same PPBUS rail, don't you think?

When inject voltage, let ALWAYS lab PSU at max current limit.
And start injecting with 1V (sometime lower), increasing if needed.

 

[Kyle93]

Only component getting hot is the GPU. Im assuming this is to new to find a replacement GPU?

Is there a way to retrieve the data if the GPU was removed?

 

[2informaticos]

Ooops you've injected voltage assuming one of these caps is the culprit?
What if is one of the chips from GPU power supply?

Remove UA710-40 (one by one) and see if/when short disappears from PPBUS_G3H.

0.002 in diode mode could be a good reading; still a chance for GPU to be alive.

 

[Kyle93]

beautiful, short disappeared from PPBUS_G3H

Do you happen to know if these chips are available on similar donar boards or do they need to be ordered separately??

 

[2informaticos]

Check online with Mouser, if you don't have donor board.

 

[Kyle93]

would sic 635 work replacing sic 621??

 

[Kyle93]

Have you had any luck finding these donar boards?

 

[2informaticos]

Dificil to get T2 scrap boards; nothing yet on Aliexpress.

 

[Kyle93]

Replacement UA710-40 arrived from digikey. Soldered and short is still gone but still no PPBUS 0v

What to check next??

 

[Kyle93]

PPBUS_G3H 1.1V drops to .950 and goes back to 1.1V at F7000

 

[2informaticos]

ISL9240 MUST generate PPBUS_G3H by itself.
Post actual diode mode at F7000.

Remove F7000/1 and check R7060 voltage.
If still low, check all resistors and caps around U7000.
Post basic voltages, PIN, VDDA/P, AUX_DET_SMC_RST_IN, AUX_OK, A/BMON, CBC_ON, SMC_RST*.
You may need to change U7000...

 

[Kyle93]

.365 diode mode

vdda 0v vddp 5v

AUX_DET .15v

amon 0v

bmon 0v

other voltages are under bga chips. Not sure how to measure those.

all voltages measured with F7000 F7001 removed

Is u7000 even available for purchase on this board?

 

[2informaticos]

Do you get any voltage at R7020???

 

[Kyle93]

.15v

 

[2informaticos]

Problems on USB-C areas.
Check diode mode at R7020 first.

 

[Kyle93]

r7020 .538