lenovo G550 zombie laptop.

[pocgoc]

Hi i have a Lenovo G550 laptop.
It has no LED lights , no charging and no sign of power.
I checked the charger 19.34v so its okay, checked the DC Jack it is sending power to the board okay. But the gateways and capaictors have power running through it.
Bad bios flash maybe? Or maybe a power controller chip.
No lights on charging
no power with charger and battery

Model :KIWA7 LA-5082P

datasheet link:
http://www.scribd.com/doc/132659282/...3da3ydwhq551tq

[pocgoc]

Re: lenovo G550 zombie laptop.















any tips on which compents to test first would be most welcome. PIcs

[Tuomo]

Re: lenovo G550 zombie laptop.

Hi i have a Lenovo G550 laptop.
It has no LED lights , no charging and no sign of power.
I checked the charger 19.34v so its okay, checked the DC Jack it is sending power to the board okay. But the gateways and capaictors have power running through it.
Bad bios flash maybe? Or maybe a power controller chip.
No lights on charging
no power with charger and battery

Model :KIWA7 LA-5082P

datasheet link:
http://www.scribd.com/doc/132659282/...3da3ydwhq551tq

First check voltages on PQ301 and PQ302.

[spidey]

Re: lenovo G550 zombie laptop.

first measure rtc battery at least 2.6v needed to power up. measure current to know if standby exist, then check 3v and +5v present. measure pwr button +3.3v, if there is then press button to see 0v. unless find the schem trace back to keyboard controller ic. still no re-program bios. still no ? connect to scope check south xtal. then check clock chip xtal. ten reflow south to see if it is the problem. if yes reball it unless change keyboard controller. But if you dont have +3 +5 v let me know.

[pocgoc]

Re: lenovo G550 zombie laptop.

first measure rtc battery at least 2.6v needed to power up. measure current to know if standby exist, then check 3v and +5v present. measure pwr button +3.3v, if there is then press button to see 0v. unless find the schem trace back to keyboard controller ic. still no re-program bios. still no ? connect to scope check south xtal. then check clock chip xtal. ten reflow south to see if it is the problem. if yes reball it unless change keyboard controller. But if you dont have +3 +5 v let me know.

Okay rtc =2.61v (ok)
Pwr button = 17.42v - pressed button 0.00v (?)
I can't get the current ,no standby?

[pocgoc]

Re: lenovo G550 zombie laptop.

First check voltages on PQ301 and PQ302.

pq301
here is the results they look fine

[Tuomo]

Re: lenovo G550 zombie laptop.

pq301
here is the results they look fine

Yes, they are fine.

Next 3V and 5V always PL401 and PL402.

[pocgoc]

Re: lenovo G550 zombie laptop.

PQ304 mosfet i have noticed, that its drains 5-8 have 0 volts and source 1-3 is 19.23v and Gateway 4 is 19.23v instead of 12.95v like pq302 and pq301 mosfet which are also FDS6675BZ

[pocgoc]

Re: lenovo G550 zombie laptop.

pq304 mosfet i have noticed, that its drains 5-8 have 0 volts and source 1-3 is 19.23v and gateway 4 is 19.23v instead of 12.95v like pq302 and pq301 mosfet which are also fds6675bz

pl401 =0.025v
pl402 =0.008v

[pocgoc]

Re: lenovo G550 zombie laptop.



RICHTEK RT8206B GQW QFN 32pin Power IC Chip PU401 is heating up and is responsible for delivering and managing 3v and 5v supply in the board. Hmm i wonder is this the origin of my problem.

[Tuomo]

Re: lenovo G550 zombie laptop.

pl401 =0.025v
pl402 =0.008v

PQ302 etc. are P type mosfet, if Gate is 19V they are closed.

Always voltages missing. Nothing works vithout those voltages.

Can you measure PU401 PIN 6 VIN, PIN7 LDO.

[pocgoc]

Re: lenovo G550 zombie laptop.

PQ302 etc. are P type mosfet, if Gate is 19V they are closed.

Always voltages missing. Nothing works vithout those voltages.

Can you measure PU401 PIN 6 VIN, PIN7 LDO.

PIN 7 IS 19.22V
PIN 6 is also 19.22v

[Tuomo]

Re: lenovo G550 zombie laptop.

PIN 7 IS 19.22V
PIN 6 is also 19.22v

PIN7 Ok, PIN 6 VL usually 5V have to check.

Can you measure PIN 1, 4, 14, 27, 28.

[Tuomo]

Re: lenovo G550 zombie laptop.

RICHTEK RT8206B GQW QFN 32pin Power IC Chip PU401 is heating up and is responsible for delivering and managing 3v and 5v supply in the board. Hmm i wonder is this the origin of my problem.

Yes it is very possible.

[pocgoc]

Re: lenovo G550 zombie laptop.

Yes it is very possible.

Thanks Tuomo , i got it going by replacing It with new one.

but now i got a dark screen , it doesn't power up the back light of the LCD. Tried 2 screens no back light on either.
I wonder is it my LCD cable, here is my LCD /dvi /Lvcds connector pinot with voltages
Any help Ill be very grateful

[pocgoc]

Re: lenovo G550 zombie laptop.

I replaced the RICHTEK RT8206B GQW QFN 32pin Power IC Chip PU401.
1. I got power.
2. It turned on but the LCD was dim.
3. plugged in the battery , charged but U50 got extremely hot.
4. RT8206B PU401 failed , started heating up again.

[Tuomo]

Re: lenovo G550 zombie laptop.

I replaced the RICHTEK RT8206B GQW QFN 32pin Power IC Chip PU401.
1. I got power.
2. It turned on but the LCD was dim.
3. plugged in the battery , charged but U50 got extremely hot.
4. RT8206B PU401 failed , started heating up again.

5VALW go to U50, and if U50 or U50 OUT is shorted it may cause RT8206B fail.

Measure U50 OUT pins resistance and C440.

[pocgoc]

Re: lenovo G550 zombie laptop.

C440 = 6.4 ohms

U50:
pin5(OC#)= 6.10kOhms
pin6(out)=6.4ohms
pin7(out)=6.5ohms
pin8(out)=6.3ohms

pin1(gnd)=0.2ohms
pin1(IN)=6.5ohms
pin1(IN)=6.5ohms
pin4(EN)=1.9ohms

[pocgoc]

Re: lenovo G550 zombie laptop.

5VALW go to U50, and if U50 or U50 OUT is shorted it may cause RT8206B fail.

Measure U50 OUT pins resistance and C440.

PIN 8 oc# = 6.10Kohms
PIN 7 OUT = 6.5ohms
PIN 6 OUT = 6.5ohms
PIN 5 OUT = 6.5ohms
PIN 4 EN = 1.9ohms
PIN 3 IN - 6.5ohms
PIN 2 IN = 6.5ohms
PIN 1 GND = 0.2ohms

C440 =6.4ohms

[Tuomo]

Re: lenovo G550 zombie laptop.

PIN 8 oc# = 6.10Kohms
PIN 7 OUT = 6.5ohms
PIN 6 OUT = 6.5ohms
PIN 5 OUT = 6.5ohms
PIN 4 EN = 1.9ohms
PIN 3 IN - 6.5ohms
PIN 2 IN = 6.5ohms
PIN 1 GND = 0.2ohms

C440 =6.4ohms

U50 OUT pins are 5V for USB its resistance should be > 300ohm.

Remove U50 and measure pins.

If OUT pins still low resistance check USB connectors and C442 and C443.