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[help] 820-01958 dead: 20v not switching

P

phantom

Member
i've found this


Once the T2 is powered from the above rails, it will read its ROM (U4770.) The T2 will then begin to start its boot up process, in which we will initialize the below rails.
PP3v_G3H: Normal voltage is ~3.0v. Produced from U7800, powers some PCH functions.
PP5v_G3S: Normal voltage is ~5v. Produced from U7650/Q7660.
PP3v3_G3S: Normal voltage is ~3.3v. Produced from U8210.
PP1v8_G3S: Normal voltage is ~1.8v. Produced from U8220.
The SSD power is then enabled to allow the T2 to boot BridgeOs.
PP1v8_VCCQIO_SSD0: Normal voltage is ~1.8v. Produced from U7800.
PP0v9_SSD: Normal voltage is ~0.9v. Produced from U7800.
PPVCC_NAND_SSD0: Normal voltage is ~2.5-2.7v. Produced from U9060.

Once the SSD is powered, and BridgeOs boots,

SO IS IT POSSIBLE THAT T2 doesn't enable those power rails for some reason?
 
2informaticos

2informaticos

Administrator
Staff member
Very likely.
Sometimes power on sequence is corrected with DFU revive; manytimes only with restore.
Keep in mind, restore will erase SSD.

Try again revive, with charged battery and trackpad connected.
 
P

phantom

Member
i've tried like 5 times always same behaviour ... what do you suggest? restore?

it's like it can't exit from dfu mode..when flashing, as soon as dfu logo disappear, it reapper after like 1 second....like it is "forced"
 
P

phantom

Member
no dfu anymore after reflashing u4770...

under the microscope, i've seen a solder blob between pin 1 of u4770 and pin 1 of c7920.

removed, but still no dfu?

maybe i've damaged u4770 "injecting" 1v from c7920 to pin 1 of u4770?
on u7901 now i have

pin 7 3,2v that goes to 0,5 tha goes to 3,2 in loop
pin 5 1,1v that goes to 0,5 that goes to 1.1 in loop
pin 1 unstable goes from 2,9 to 3,3 in loop
pin 2 1,8 to 0 in loop
pin 3 1,1 to 0 in loop

I WANT TO KILL MY SELF
 
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P

phantom

Member
At the beginning, one of the first thing i’ve done, before changing u7650, before changing cd3217etc, was to backup u4770 and flashing it with a dump found online.

So until now, i have had u4770 “working” with a dump

No i have those strange voltage (i Think it’s impossible to have 3v in a line where i should have 1,1v!!) after flashing the original backup,..,
 
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2informaticos

2informaticos

Administrator
Staff member
"i Think it’s impossible to have 3v in a line where i should have 1,1v"
Which line?

U7901 may be damaged; try changing it.
First check diode mode to ground at 1V1_SLPDDR.
 
P

phantom

Member
All Lines ok in diode mode. Like i said before, same thing even with another u7901

About 3v on a 1,1 Lines:


Here all the measurememt of u7901

pin 7 3,2v that goes to 0,5 tha goes to 3,2 in loop
pin 5 1,1v that goes to 0,5 that goes to 1.1 in loop
pin 1 unstable goes from 2,9 to 3,3 in loop
pin 2 1,8 to 0 in loop
pin 3 1,1 to 0 in loopU
 
2informaticos

2informaticos

Administrator
Staff member
"About 3v on a 1,1 Lines"
I don't see more than 1.1V on pin 3 & 5.

1V1_SLPDDR is used by T2; basically for its internal RAM.
Your T2 may be faulty.

This power cycle may also have another cause.
T2 may detect a later fault in power on sequence.
 
2informaticos

2informaticos

Administrator
Staff member
"Yes , i have 3v on a 1,1 Line!"
Seriouslly, where?

Do not say that you are worrying about pins 2 & 7 of U7901.
A signal with "1V1" on its name, doesn't mean to be 1.1V level; put some logic on your job man.
 
P

phantom

Member
Ok sorry….
This is the situation in this Moment:

I have 20v on both port even with power supply only

And 3,3 unstable….

Seems like a bootloop

Dropbox

www.dropbox.com www.dropbox.com

even other power rails like 1,8v have the same behaviour
 
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P

phantom

Member
i repeat, if i remove u7901, 3v3_g3h become stable, but it doesn't switch to 20v,
if i solder u7901, 3,3v (and others voltages) become unstable but it switch to 20v


when u7901 is soldered

ihave

P1V1SLPDDR_RAMP 3,24v that goes to 0 in loop
PP1V1_SLPDDR 1,1v that goes to 0,5 to 0 in loop
PP1V1_SLPS2R 1,1v that goes to 0,5 to 0 in loop
P1V1_SLPDDR_SOCFET_EN 1,8 that goes to 0 in loop
 
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2informaticos

2informaticos

Administrator
Staff member
You may have problems with CPU, or even T2.
The power fluctuation can also be caused by short/overcurrent on a secondary power supply.

This is not an exact science.
Do you think is worth to continue with this board?
Such machine can be found for low price; with broken screen, for example.
 
P

phantom

Member
But what the hell can be happen?? i've simply reprogrammed u4770 e soldered it back....i don't want to give up...please help me 2informaticos....please please plese...


is it possible that the solder blob between pin 1 of u4770 and pin 1 of c7920 has damaged something? what can i check?

why if i remove u7901, 3v3_grh come back stable???
 
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