Toshiba Satellite L500 - No power on

[marcellodj]

Mainboard: KSWAA LA-4982P
Issue: battery led charger on,ac led on, whe power led goes on to green,fan spins,display is blank,after 2-3 secs power led go off.

Any ideas?

thanks

[godin]

Re: Toshiba Satellite L500 - No power on

Try reseating the memory

[marcellodj]

Re: Toshiba Satellite L500 - No power on

Replaced memory,cpu etc; same result is a component level issue.thanks anyway

[Lobo]

Re: Toshiba Satellite L500 - No power on

The L500 series of Toshibas are plagued with defective motherboards. I have an L505 where the southbridge is completely wiped out. No audio, USB ports, or SD card reader. Everything else works except for those.
I had video problems as well. It wasn't detecting that the lid was open...try turning on with the lid barely cracked open. Also try an external monitor to see if that works. Sometimes when I hooked up an external, the laptop screen would magically come back on.

[ratdude747]

Re: Toshiba Satellite L500 - No power on

Sounds like a toasted mainboard...

[pcbmaniac]

Re: Toshiba Satellite L500 - No power on

Hi all,
i have a friend's laptop Toshiba L500 with LA4981 motherboard.
This device have several problems. Here are the measures i 've made so far:

I have Vin voltage, 3VALW and 5VALW but no any VS voltage since no VSB voltage to activate the voltage regulator chips.
When i give 19V power from adapter, i have power led on.
Also, if i connect a battery, i do have charging led on too.
If i press power on button, nothing changed. Mobo is dead.
Low recistance to +1.05V power trail about 1.2 ohms measure with multimeter and total capacitance about 220uf measure with ESR meter. Is that right?
I jumper off the PJ6 and PJ9 and low resistance remains on the right side after the PL6 inductor.
Trying to give 1.0V DC voltage with regulated PSU and the total current was about 400mA but no hot components appeared.
Also, i don't have 32.768Hz pulse in RTC and i will do reprograming for the U46 eeprom chip too.
Since i don't have profesional raballing system, only hot air, is there any chance to do anything with this mobo? Any measurement steps to do next?
Here is the schematic file for my mobo.
TIA

ftp://helpedia.com/pub/temp/uploads/...20LA-4982P.pdf

[atsio]

Re: Toshiba Satellite L500 - No power on

Replace Northbridge.

[pcbmaniac]

Re: Toshiba Satellite L500 - No power on

That's the best way of course but i don't have professional equipment to do it. Only hot air gun with regulated temperature. What can i do with it? Do i need preheater too?
P.S forget to mention that my friend tolled me that he put this board for 10 min into kitchen oven at 250C. Before that, the pcb triggered from power button and the fan starts and then stops.

Ευχαριστώ για την απάντηση πάντως!

[dj_ricoh]

Re: Toshiba Satellite L500 - No power on

10 min its overkill.

I might say i'm expert with oven and i try almost everything with the oven.

8min max. After it reach 80c you close the door and count 8 min.
Under 20L its with stages. 2min 100c 2 min stop 2 min 150c 1min stop 1 min 200c

[atsio]

Re: Toshiba Satellite L500 - No power on

You have shorted +1.05V power rail (shorted northbridge). You need to replace it.

[pcbmaniac]

Re: Toshiba Satellite L500 - No power on

My mistake. My friend told me that he use oven about 10 min at 180C. The ic looks ok and not popcorned.
I will try to use a small preheater at the bottom of the pcb and my hot air gun on the top of it. I do have a 2 display meter for temperature measurement and 2 probes also.
What temperature profile should i use for it? I mean the time diagram for melting the soldering.

[gcomputers]

Re: Toshiba Satellite L500 - No power on

Hi i m working with same LA-4892p

Power led stay green , battery led stay orange but power up 2 sec and turn off.

on coils i have 3,3 v , 5v , on bios chip 3,3v ok.

PQ9 have pin 1234 19v , pin 5678 16.6v .

PU6 VIN is 16.6v

Replaced pq9 replaced pr49 replaced pu5 isl62651.

NOW i cheched the caps of NB (with adapter inserted) and all are shorted with ground.

THAT S THE PROBLEM ON THIS MODEL FROM YOUR EXPERIENCE ?

IF IT IS THE PROBLEM CAN I REBALL OR NEED TO REPLACE ABSOLUTELY .

[gcomputers]

Re: Toshiba Satellite L500 - No power on

flashed bios no change

[kiraro]

Re: Toshiba Satellite L500 - No power on

Hi i m working with same LA-4892p

Power led stay green , battery led stay orange but power up 2 sec and turn off.

on coils i have 3,3 v , 5v , on bios chip 3,3v ok.

PQ9 have pin 1234 19v , pin 5678 16.6v .

PU6 VIN is 16.6v

Replaced pq9 replaced pr49 replaced pu5 isl62651.

NOW i cheched the caps of NB (with adapter inserted) and all are shorted with ground.

THAT S THE PROBLEM ON THIS MODEL FROM YOUR EXPERIENCE ?

IF IT IS THE PROBLEM CAN I REBALL OR NEED TO REPLACE ABSOLUTELY .

PQ9 and PQ8 most be a P-channel mosfet that's mean the "Pin 4" must have 0v to find a 19v output ,verify if you change the right type if not you will d'ont have any output (i have the same problem before with another laptop how he arrive from another repair center and i found the two transistor of power changed with N-channel , but the right type was P-channel a first time the motherboard dead nothing on output after change P-channel she become to see light and i found a +VSBP missing because PQ6 was faulty , i replaced and all is ok ).

Second , verify the +VSBP without pressing power button , you must have on PQ6( Pin2=3.3v(used for command to get the output because it's a switch transistor), Pin3=19V(B+), Pin1=+VSBP(19V) )
sorry for my bad english .
hope that help you .

[keeney123]

Re: Toshiba Satellite L500 - No power on

My mistake. My friend told me that he use oven about 10 min at 180C. The ic looks ok and not popcorned.
I will try to use a small preheater at the bottom of the pcb and my hot air gun on the top of it. I do have a 2 display meter for temperature measurement and 2 probes also.
What temperature profile should i use for it? I mean the time diagram for melting the soldering.

I do not know what type of oven you are using, but ovens need to be calibrate. Even ones used in industry can be 20 degrees off from the set temperature and can fluctuate. If you use one at home no telling what it will do. In industry they are calibrate down to +/- 2 degrees. This takes several hours because it has to stabilize. One can use a Bittle to do this. This instrument is calibrated once a year to the National Bureau of Standards.

[gcomputers]

Re: Toshiba Satellite L500 - No power on

PQ9 and PQ8 most be a P-channel mosfet that's mean the "Pin 4" must have 0v to find a 19v output ,verify if you change the right type if not you will d'ont have any output (i have the same problem before with another laptop how he arrive from another repair center and i found the two transistor of power changed with N-channel , but the right type was P-channel a first time the motherboard dead nothing on output after change P-channel she become to see light and i found a +VSBP missing because PQ6 was faulty , i replaced and all is ok ).

Second , verify the +VSBP without pressing power button , you must have on PQ6( Pin2=3.3v(used for command to get the output because it's a switch transistor), Pin3=19V(B+), Pin1=+VSBP(19V) )
sorry for my bad english .
hope that help you .

Thanks for the reply.
First i replaced with p-channel 4407a .
Checked PQ6 pin2=3v AND pin 1 3 have 16.6v i think that s the problem lose power in one point .

IF I MAKE JUMP AT PQ9 PIN 1 WITH PIN 5678 OK START NORMALY BUT where lose this power?????????????


Any other help

[gcomputers]

Re: Toshiba Satellite L500 - No power on

Hi to all.
removed PR49 voltage remain 16.6v so i checked PQ14 PIN2 19V PIN 1 IS SHORTED replaced but no change the same 16.6v
alslo PQ11 all pin have 19v stable.
Any suggestion

[kiraro]

Re: Toshiba Satellite L500 - No power on

Hi to all.
removed PR49 voltage remain 16.6v so i checked PQ14 PIN2 19V PIN 1 IS SHORTED replaced but no change the same 16.6v
alslo PQ11 all pin have 19v stable.
Any suggestion

hi, check value of "PR54" and "PR55" those resistances connected to P3 who is connected to the output of PQ9 ,may be one of them was cut or damaged and not have the correct value of resistance that cause de lose of power on output.
if they have a correct value check "PR167" and PQ12 .

*sorry for my bad english.

[gcomputers]

Re: Toshiba Satellite L500 - No power on

Thanks for your reply.
today i make some mistake , removed pq14 inserted adapater to measure and burned PU5 ,
replaced pu5,
now power led blinking continuously, and power on PQ9 pin 5678 and in sequel VIN from 16.6 descend to 10.3-13v (up and down) .

i checked the problem is around PU5 removed PL20 pin 2 have 19v stable

(replaced pl20. pq22. pq23 .pq27) no change
now when i make i jump from pq9 pin 1234 with 5678 ,,,, PU5 make very very warm
replaced 3 time PU5 with new and used ic but no lucky ..

NOW what can i do please ????????

[gcomputers]

Re: Toshiba Satellite L500 - No power on

any help please