Lenovo Y700 NM-A541 Advanced Engineering

[Olles4]

Hello Gentlemen's.

I need some advice. I just removed form my motherboard BGA graphics card (it was shorting almost everything to ground)
I was hoping after removal laptop will bot but i was wrong.
Do you think is there a way to boot the laptop in some kind of safe mode where laptop will run on integrated graphic card?

Here are the schematics from the board https://drive.google.com/file/d/1hxb...d_ytQy5yN/view

Thank you in advance.

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Update: i found UMA mode but im not sure how should i approach it
(sheet 24 of 66)

[mcplslg123]

Re: Lenovo Y700 NM-A541 Advanced Engineering

But that part has all components @ meaning NO Stuff. Btw, what's the status of motherboard. Whats your problem? Is it turning on?? Is it posting??

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

But that part has all components @ meaning NO Stuff. Btw, what's the status of motherboard. Whats your problem? Is it turning on?? Is it posting??

Oh I see I didn't know that. Whole story is, one day I tried to turn on my laptop and won't turn on. But power was present because I heard the hdd and the fans for a sec. I tried it turn on and off several times but suddenly no more noises. I opened up my laptop took out the motherboard and a saw a blown cap. I brought my laptop to a repair shop they've told me the gpu is shorted I measured it myself and yes there was a short from gpu trough whole board on B+ . I removed the gpu and all the shorts is gone replaced the blown cap. but I getting non response from the motherboard it won't turn on. Not even the charging led or something.

[mcplslg123]

Re: Lenovo Y700 NM-A541 Advanced Engineering

So completely dead unit. Lets make a fresh beginning

01. Locate the 2 dc-in mosfets(PQ101-102) and measure voltage on Pin1/4/8 for both the fets.
02. Measure resistance on all the coils(with no power attached)
03. Measure resistance on CLR PR102

Give us these measurements and lets see what can be done to fix it.

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

So completely dead unit. Lets make a fresh beginning

01. Locate the 2 dc-in mosfets(PQ101-102) and measure voltage on Pin1/4/8 for both the fets.
02. Measure resistance on all the coils(with no power attached)
03. Measure resistance on CLR PR102

Give us these measurements and lets see what can be done to fix it.

PQ101 pin1 3.7V for 30 seconds than 0.3V
pin4 600mV
pin8 20.55V
PQ102 Pin1 160mV
Pin4 160mV
pin8 0V

BUT all coils shorted to ground around the proccesor..
What do you think ?

[mcplslg123]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Coils for cpu will beep in diode mode as they have very low resistance. Better to measure them in resistance mode.

So ,1st dc-in mosfet is not allowing 19V to cross. Now measure resistance)meter set to 200K or higher) scale

pin1-4
pin1-8
pin4-8

Measure for both PQ101/102.

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Coils for cpu will beep in diode mode as they have very low resistance. Better to measure them in resistance mode.

So ,1st dc-in mosfet is not allowing 19V to cross. Now measure resistance)meter set to 200K or higher) scale

pin1-4
pin1-8
pin4-8

Measure for both PQ101/102.

PQ 101 1-4 no readings
1-8 39,6kohm but somtime 78kohm
4-8 no readings

PQ 102 1-4 no readings
1-8 98kohm but sometimes 180kohm
4-8 no readings

[mcplslg123]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Pin1-8 thats drain to source reading is too low. Take the mosfet out of board and measure resistance of mosfets out of circuit(meter set to 1M or higher scale this time). repeat the same measurements on pcb pads of PQ101/102 as well.

Seems like one of the mosfet is shorted.

You didnt mentioned the resistance on CLR??

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Pin1-8 thats drain to source reading is too low. Take the mosfet out of board and measure resistance of mosfets out of circuit(meter set to 1M or higher scale this time). repeat the same measurements on pcb pads of PQ101/102 as well.

Seems like one of the mosfet is shorted.

You didnt mentioned the resistance on CLR??

PR102 is 0ohms on the board

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Update i replaced both PQ101 and PQ102 for a new one but still not turning on.
I measured some stuff on around the board and found Capacitors next to PL701 (PC707 and PC706) are shorted and the short goes all the way around the CPU

Where can i inject Voltage to see what gets hot and how much Volts/amps?

[Sephir0th]

Re: Lenovo Y700 NM-A541 Advanced Engineering

First share exact resistance to GND please, before concluding a short to GND, where actually no short to GND is present.

[mcplslg123]

Re: Lenovo Y700 NM-A541 Advanced Engineering

PR102 is 0ohms on the board

Is this resistance across the pins of this resistor or its resistance to GND?? I asked you to measure resistance to GND on any pin of PR102. pl. clarify.

PS: Dont inject any voltage without diagnosing as that step may render the board unrepairable. Dont hurry up and have patience. We're trying to understand whether +19V rail is shorted or not. You didnt give resistance to GND on all coils which i asked for earlier. Such half baked incomplete answer wont help you in solving it.

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Alright. Ground to PR102 is 0,950kohm on both sides
Coils :
Pl; 101 15,7kohm
102 14,6ohm
202 3,5kohm
802 75,1ohm
701 19,1ohm
401,402,403 1,5ohm
404,405 2,8 ohm
406 7,9 ohm
603,606 0,950kohm
703 220ohm
301 98ohm

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Pin1-8 thats drain to source reading is too low. Take the mosfet out of board and measure resistance of mosfets out of circuit(meter set to 1M or higher scale this time). repeat the same measurements on pcb pads of PQ101/102 as well.

Seems like one of the mosfet is shorted.

You didnt mentioned the resistance on CLR??

New mosfets on board
PQ101 D-S 3,12kohm
102 D-S 3,5kohm

[Sephir0th]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Alright. Ground to PR102 is 0,950kohm on both sides
Coils :
Pl; 101 15,7kohm
102 14,6ohm
202 3,5kohm
802 75,1ohm
701 19,1ohm
401,402,403 1,5ohm
404,405 2,8 ohm
406 7,9 ohm
603,606 0,950kohm
703 220ohm
301 98ohm

A) PL102 is not existent on your board. Do you mean PL101?

B) Also the resistances around the CPU (PL401 - PL406 are way too low for my taste.

And now to the worst thing you made and maybe the origin of your issue:

Although you even managed to remove the GPU, you did NOT solve the short between B+ AND GPU_CORE for some unbelievable reason...

Likely PL703 has to be deactivated too, for your conversion.

how do you think could this work?

However, likely still multiple issues present, so sorry to tell that, but after all this mess it is probably already beyond repair. The board was in need of a experienced technician.

Actually I wonder whether the GPU was repairable in the beginning. A high side short B+ to GPU_Core isn't always the end of the repair.

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Is this resistance across the pins of this resistor or its resistance to GND?? I asked you to measure resistance to GND on any pin of PR102. pl. clarify.

PS: Dont inject any voltage without diagnosing as that step may render the board unrepairable. Dont hurry up and have patience. We're trying to understand whether +19V rail is shorted or not. You didnt give resistance to GND on all coils which i asked for earlier. Such half baked incomplete answer wont help you in solving it.

What do you think ?

[mcplslg123]

Re: Lenovo Y700 NM-A541 Advanced Engineering

I think By PL102 he meant PL201(3VALW). If this is correct, then you do have short on this rail. PU201,pin5-Whats is the voltage there?? Resistance to GND on this pin(Resistance should be measured without power and if already power is attached, remove power,wait for 2 minutes and then measure. Else you may get a wrong reading.

[Olles4]

Re: Lenovo Y700 NM-A541 Advanced Engineering

I think By PL102 he meant PL201(3VALW). If this is correct, then you do have short on this rail. PU201,pin5-Whats is the voltage there?? Resistance to GND on this pin(Resistance should be measured without power and if already power is attached, remove power,wait for 2 minutes and then measure. Else you may get a wrong reading.

Yes i meant PL201 sorry for the misunderstanding.
PU201 pin5 to ground resistance is 45,7kohm

[mcplslg123]

Re: Lenovo Y700 NM-A541 Advanced Engineering

Yes i meant PL201 sorry for the misunderstanding.
PU201 pin5 to ground resistance is 45,7kohm

Why not answer completely? I asked for voltage reading on same pin as well.