Lenovo g505 no power

[asem18]

hello everyone , Lenovo G505 no power - LA-9912P.
when i plug charger , i find 0V at PF101.change cable same thing.
No short to ground , i find 88 Kohm on both side of PF101 with multimeter .
i inject power on PL101 = not shorting.
I find no Volt too at PQ102A ( ADP_ID ).
I m so confused ,What to Chek else please!

http://www.s-manuals.com/motherboard/compal_la-9912p

[Techtiger]

Re: Lenovo g505 no power

Your charger is faulty or PQ301 /302 short ,you should get +19V on PF101 inject +19V on PL101 and see if the 1st Fet is switching voltage on S D G?

[asem18]

Re: Lenovo g505 no power

Thank you techtiger for your help
I use power supply..i inject 19v as you said .

[Techtiger]

Re: Lenovo g505 no power

Put the multimeter continuity test mode test S G short or not
Change the 2nd Fet it’s short Gate Voltage is to high most probably short Between S G

[piernov]

Re: Lenovo g505 no power

Measurements are wrong, both gate are tied together, they cannot have a different voltage.
It'd rather be first MOSFET shorted, but cannot tell without exact measurements.

[mcplslg123]

Re: Lenovo g505 no power

Measurements are wrong, both gate are tied together, they cannot have a different voltage.
It'd rather be first MOSFET shorted, but cannot tell without exact measurements.

Agreed but going by the measurement of 1st mosfet, if that's correct, problem may lie elsewere.

[asem18]

Re: Lenovo g505 no power

Back again..thank for your help...i change both mosfet ( Pq301 Pq302) same issue.
Resolder the origional mosfet ( tested no short between S and G ) and i inject 19v at the drain of Pq 301 and find 19 V at PR301, push the power button and the laptop works .
i re-connect the cable at JDCIN1 and with power supply i find only 0.890v at PR301.
What to shek else !!

[asem18]

Re: Lenovo g505 no power

maybe this help !

[mcplslg123]

Re: Lenovo g505 no power

you need to focus on PU301-charger ic. What is the measurement on pin 1,2,5,6,7,8,9,20 to begin with?? you are not getting voltage on drain of PQ301 as pin4(gate) is not opening. Since you have schematic , you can probe the components related to gate of pq301. However, i suspect a bad charger ic.Also check whether any of the pins listed here of charger ic is showing low resistance to gnd.

[asem18]

Re: Lenovo g505 no power

Sorry to be late .
mcplslg this is the measurments that you ask for With wire soldred on Drain of PQ 301
Pu301 =
1/2 = 20v
5 = 4.2mv
6 = 2.8v
7 = 0.5mv
8/9 = 3.3v
20 = 20v

And the laptop work !

[asem18]

Re: Lenovo g505 no power

PF101 with diode mode there's a short = 0.001v

[Duranitron]

Re: Lenovo g505 no power

Im confused PF101 is a fuse its normally shorted.l

[Duranitron]

Re: Lenovo g505 no power

so you already repaired it? is it a cold solder?

[asem18]

Re: Lenovo g505 no power

i mean short to ground...after trying to turn on from jdcin..nothing and the short dissappear

[smali]

Re: Lenovo g505 no power

are you tried and checked FET PQ301 and Pq302 may be problem in FET internal Gate open prob check with other P channal FET.
and also check Your DC Jack????

[asem18]

Re: Lenovo g505 no power

i changed the 2 mosfet with another p-channel..same issue..when i plug mu power supply no volt on jdcin

[mcplslg123]

Re: Lenovo g505 no power

Sorry to be late .
mcplslg this is the measurments that you ask for With wire soldred on Drain of PQ 301
Pu301 =
1/2 = 20v
5 = 4.2mv
6 = 2.8v
7 = 0.5mv
8/9 = 3.3v
20 = 20v

And the laptop work !

These measurements seems fine. I doubt your dc jack is faulty.

[mcplslg123]

Re: Lenovo g505 no power

Measure resistance on PF101 with dc jack plugged in and dc jack NOT plugged in. No power should be applied while measuring.

[asem18]

Re: Lenovo g505 no power

Thank you mcplslg
89.5 kohm with or without dc jack

[smali]

Re: Lenovo g505 no power

Thank you mcplslg
89.5 kohm with or without dc jack

May be the problem is not tracing on removal of Jack ...may be when you connecting the charger pin with the DC Jack that time the Jack creating problem...if you have another Jack try with that....and also trace the PCB line connectivity between the DC Jack and pf101