does not turn on lenovo x1 carbon

[karlox]

I work with a logic card from a lenovo carbon x1 laptop, I have a doubt with pwm U7, 19v reaches #36 AVVC but in #30 vint20 I have only 0.484v, the equipment does not turn on. in #38 acp #37 acn I also have 0.484v. I have damaged the pwm? I am using a regulated source and the current draw is 0.00

any suggestions to determine the failure of the u7?


Thank you so much

[mcplslg123]

Re: does not turn on lenovo x1 carbon

What is the motherboard markings? Link schematic if available. U7 is charging IC? If yes, what is the marking on it?

[karlox]

Re: does not turn on lenovo x1 carbon

What is the motherboard markings? Link schematic if available. U7 is charging IC? If yes, what is the marking on it?

sorry for the lack of information. well it is a Thinkpad Carbon X1 motherboard, LMQ-1 MB 12298-2. the <U7> its matriculation is BQ24760RSBR, is the one I guess is dead, as I have the AVCC line with 19v, but the signal fades there..... thanks






MOD EDIT: Schematic -> https://www.badcaps.net/forum/showpo...4&postcount=32
.

[mcplslg123]

Re: does not turn on lenovo x1 carbon

VINT20 must be 19V for charging IC to work. You need to check page 56 of schematic. Voltage on S-D-G of Q9/Q36? If nothing wrong found here, then probe Q51/78/61/79/107.

[karlox]

Re: does not turn on lenovo x1 carbon

VINT20 must be 19V for charging IC to work. You need to check page 56 of schematic. Voltage on S-D-G of Q9/Q36? If nothing wrong found here, then probe Q51/78/61/79/107.

hello, annex tensions.

Q9=S19v/D19.4mv/G18.61V, Q36=S17.4mV/D=0.484V/G16.5mv, Q51= pin1 18.14v/pin2 17.73v/pin3 18.52v, Q78=Pin1 18.15v/Pin2 5.0mV/Pin3 0.0V, Q61=Pin1 18.94V/Pin2 7.0mV/Pin3 0.0V, Q79=Pin1 17.75V/Pin2 0.1mV/Pin3 0.0V, Q107=Pin1 18.61V/Pin2 18.94V/Pin3 18.97V.

in C9028 in the VCC3B line I have a short or a low resistance, I am confused, because I have no consumption, nor excess temperature in the whole board. in the whole board.


Thank you, hopefully there is some guidance on where to go, this is my weekly stress at the moment.

[mcplslg123]

Re: does not turn on lenovo x1 carbon

VCC3B showing low resistance is not a good sign and perhaps your issue may be related to this. this rail touches almost all the components on the motherboard. You can inject 1V/1A and gradually increase the amp to 5A-10A to find out what is heating up. You'll need a dc supply to do this. Voltage can be injected anywhere on VCC3B line.
Btw, what's the exact resistance on this line??

[karlox]

Re: does not turn on lenovo x1 carbon

VCC3B showing low resistance is not a good sign and perhaps your issue may be related to this. this rail touches almost all the components on the motherboard. You can inject 1V/1A and gradually increase the amp to 5A-10A to find out what is heating up. You'll need a dc supply to do this. Voltage can be injected anywhere on VCC3B line.
Btw, what's the exact resistance on this line??

hola, buen dìa.

at VCC3B=0.4 ohms... I'll inject voltage according to your suggestion let's see if I roast it once..
thnks!!

[karlox]

Re: does not turn on lenovo x1 carbon

I will leave the motherboard as deceased, the processor is compromised, the VCC3B line is heating up the gpu..

Thanks for the support

[mcplslg123]

Re: does not turn on lenovo x1 carbon

Is GPU being heated or CPU? If it's GPU .the mb may be repairable.

[piernov]

Re: does not turn on lenovo x1 carbon

I bet they meant PCH.

[karlox]

Re: does not turn on lenovo x1 carbon

Is GPU being heated or CPU? If it's GPU .the mb may be repairable.

hello! good afternoon, in the end i spent 5 hours more to the equipment, and it was worth it, i made it revive. i disconnected the processor, and the failure continued, it was frustrating to find a short resistor. but it lives. thanks for the support.

[mcplslg123]

Re: does not turn on lenovo x1 carbon

You mean you de-soldered the SOC from motherboard or you lifted just the coils? Which resistor exactly?

[rbvndonh]

Re: does not turn on lenovo x1 carbon

Could you tell which resisotr or which area?