Toshiba C660-11W PWWAA LA-6841-P after 7sec the mobo shut's down

Hello

I've got a Toshiba C660-11W, mainboard PWWAA LA-6841-P and it wont start.
When I press the power button, the fan starts and the ON led light up then after 7sec the mobo shut's down.
Tryed to remove/switching memory's and CPU. If I remove the CPU and start the PC without is the mobo reacts as same.

I've searched for any info or the mobo schematic and didn't find nothing.

So I need your knowledge.

Thanks for your attention

What is the current drawn, while the mobo is on?
Please measure voltages on all coils.

First measure motherboard without CPU and RAM, and later with CPU and RAM.

indicheq napisał(a):What is the current drawn, while the mobo is on?
Please measure voltages on all coils.

First measure motherboard without CPU and RAM, and later with CPU and RAM.

The current draw without cpu and ram is 0.409A and with cpu and ram is 0.204A.

What coils do you refer? Maybe this is a noob question but dont blame me cus I'm a Laptop repair noob.

Today I found a hot component. I think this is a SMD resistor 1R0 and is resistence 23OHM.
I took a photo of it.



Can it be the cause?

Thanks

With what is connected to this resistor?
Perhaps this element is broken, but first you need to perform measurements.
Measure resistance relative to the ground (motherboard completely disconnected from the power supply and battery):
PL332
PL353
PL152
PL402
PL503, PL504 (on these coils resistance should be the same).

Measure voltage relative to the ground on this same coils (motherboard connected to the power supply and and switched on).

indicheq napisał(a):With what is connected to this resistor?
Perhaps this element is broken, but first you need to perform measurements.
Measure resistance relative to the ground (motherboard completely disconnected from the power supply and battery):
PL332
PL353
PL152
PL402
PL503, PL504 (on these coils resistance should be the same).

Measure voltage relative to the ground on this same coils (motherboard connected to the power supply and and switched on).

Hi,

PL332 - 1,638 KOhm ; 3,315V
PL353 (Only found PL352) - 150,8 OHM ; 5,159V
PL152 - 374,9 OHM ; 1,502V
PL402 - 14,7 OHM ; 1,059V
PL503 - 18,6 OHM ; 0,019V
PL504 - 18,9 OHM ; 0,022V

I've done a diagram of the connection's for the hot component:

This resistor: PR541 - 1Ω_0603_5%
Voltage before and after this resistor should be 5V.

Before you replace this resistor, please measure resistance on pin 31 (ISL6266AHRZ) relative to ground.

indicheq napisał(a):This resistor: PR541 - 1Ω_0603_5%
Voltage before and after this resistor should be 5V.

Before you replace this resistor, please measure resistance on pin 31 (ISL6266AHRZ) relative to ground.

Sorry Sir indicheq but this mobo is low on the component detail. where is that resistor? I dont have the mobo schematic.

Pin 31 to ground is 101,3 OHM.

Thanks for your Attention

A hot component on this mobo is this resistor (PR541), should have a 1Ω.

indicheq napisał(a):A hot component on this mobo is this resistor (PR541), should have a 1Ω.

On one side is 5,102V and on the other side is 2,2V

I've changed PR541 to 1Ω smd and didn't work, it get's hot to.

After change i've got 5,012V on one side and on the other i've got 3,6V.

Check PC538 and PC539, if they are proper, replace PU500 (ISL6266AHRZ).

indicheq napisał(a):Check PC538 and PC539, if they are proper, replace PU500 (ISL6266AHRZ).

Checked the capacitors and the PC538 as 2.5uF and the PC539 as 3nF insted 22nF.

I will replace the capacitor and order the PU500.

Again I apreciate all of your attention.

Many thanks

w00dman napisał(a):

indicheq napisał(a):Check PC538 and PC539, if they are proper, replace PU500 (ISL6266AHRZ).

Checked the capacitors and the PC538 as 2.5uF and the PC539 as 3nF insted 22nF.

I will replace the capacitor and order the PU500.

Again I apreciate all of your attention.

Many thanks

Hi again,

Changed the Pu500 and nothing, the resistor is getting hot to.

Is there anything that I can done?

Thanks for all

Check voltage on pin 22 and 31 of PU500. There should be 5V. Did you replaced capacitor PC539?
Also check voltage on PQ501 and PQ503.

HMOG.....

Now the board wont turn on...

I've done the measure on the. pin 22 and 31 and got 2,4V insted 5V

When moved to PQ501 and PQ503 I didn't get nothing. Checked the power supply and when I plug the chord the tension low's to 0,4V.
I've measured the PQ501 and got a 180Ω between pin 4 and 5,6,7,8. Measured PQ503 and between those pins got 1,035KΩ.
Have the PQ501 after all tries blow? I don't think that I've done a short circuit because I was really carefully.

-- 23 January 2014, 00:53 --

Removed the PQ501 and now the mobo works again but still faulty. The resistor is getting HOT.
Is this because the PQ501 is missing?

On PQ503 I'm getting 18.5V between 1,2,3,4 and 5,..,8 pins.

Thanks for all and sorry all this question

-- 23 January 2014, 02:10 --

Measured the PQ501 and got 1.2Ω between pins 1,2,3 and 5.... 180Ω between pin 4 and 5...
Checked the datasheet and ordered one tpca8023-h.
Is that causing the trouble?

thanks again

w00dman napisał(a):Is this because the PQ501 is missing

Motherboard will not work without PQ501.

On PQ503 I'm getting 18.5V between 1,2,3,4 and 5,..,8 pins.

Why you measured between this pins? All voltage should be measured between pin and ground. Also resistance should be measured in this way to check if there is any short circuit.

In your case there is no +CPU_CORE which means PU500 is not working (or powered) as it should. Hot resistor is PR541. One side is 5V, other side is going to pin 33 of PU500 (PVCC - should be 5V) and got only 2.4V. If you already changed PU500, in my opinion, the problem is in one (or more) of transistors: PQ501, PQ502, PQ503 and PQ504. PVCC is a 5V power supply for gate drivers, and is connected to internal boot strap diode (in PU500) - BOOT1 and BOOT2.

"Measured the PQ501 and got 1.2Ω between pins 1,2,3 and 5.... 180Ω between pin 4 and 5...
Checked the datasheet and ordered one tpca8023-h.
Is that causing the trouble?"

According to this, I think this PQ501 it's faulty 'm I right?

Should I take out of the circuit the Q503,502,504 or let them on the circuit?

Measured the voltage on Pq503 and got 18.8V on pins 5...8 and on 1..4 0V, this relate to ground.
PQ502 and 504 had no voltage on they pins.