Toshiba Satellite L50-A-122 Charger Light Pusling

[Kambi13]

Hi there, today in the menu, is a Toshiba Satellite L50-A-122 that has a puslng charger light.
I've measured all the coils and the values seems ok, charger IC also seems, ok.

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Charging LED = Orange color ?

Is the pulsing not normal ? Could it just mean that the battery is charging?

What does the Windows desktop report for the battery status?

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

No leds come up, just the led in the power brick is flashing. The laptop wont turn on

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

I do feel the first power mosfet very hot, i've put some IPA on top of it and while is evaporating it's like pulsing the same way the charger light, I've replaced with a new one but the problem remains the same

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Link or post the schematic you are using.

The fault is often with the 2nd dcin mosfet.

You can remove it and check if the first mosfet is still hot or not.

With the 2nd mosfet removed, what is the resistance to ground of the source ? Drain ?

Best is to first remove all power. Meter in resistance mode.

Check the resistance across:

Source & drain
Source & gate
Gate & drain

Pins of each dcin mosfets. Post all measurements. This will confirm if the mosfets are defective or not.

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Schematic is for P50-A VGSG-GS Rev21 - wich matches the board here

Removing the second mosfet will get me 19,4v to the drain of the first mosfet, wich I already tried

Without the 2nd mosfet in place this is the reading I get in the pads
Source & drain - 126,5k
Source & gate - 0
Gate & drain - 129,7k

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Post the schematic - could only find a BV file in my database.

These are the readings WITHOUT the mosfet on the board? They are too low.

Check the same measurements of the mosfet that was removed while it is on your lab bench. What are the measurements?

What are the resistance readings of the first DCin mosfet?

Also, when the adapter is attached, what is the gate voltage on the first DCin mosfet? It should be ~25v if the mosfet is passing the adapter voltage through to the 2nd mosfet.

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Sorry, I dont have the schematic, only boardview also

Forgot this is a p-channel mosfet

Here's the correct readings

1st Mosfet
Source & drain - 1,5 ohms
Source & gate - 231,10 ohms
Gate & drain - 232,8 ohms

2nd Mosfet - pads only
Source & drain - 133,5k
Source & gate - 240,7 ohms
Gate & drain - 133,6k

2nd Mosfet - out
Source & drain - 12,67M
Source & gate - OL
Gate & drain - 133,6k

Gate voltage on the first DCin mosfet - 19v

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

1st Mosfet
Source & drain - 1,5 ohms
Source & gate - 231,10 ohms
Gate & drain - 232,8 ohms

These are very low resistance readings. In ohms ?

Also, if P-channel, with the gate @ ~19v, the P-channel mosfet should be OFF.

The gate should be lower than the voltage the mosfet is passing source/drain.

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Sorry it's an N-Channel mosfet here's the datasheet (lack of sleep...)

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Resistance is still low.

For N-channel, the gate should be about 6 volts higher than the voltage the mosfet is passing source/drain.

What IC is driving these 2 x DCin mosfets ? That will be the charger IC. Is it the BQ type? Post the topside markings from the charger IC.

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

For N-channel, the gate should be about 6 volts higher than the voltage the mosfet is passing source/drain - So true, but that's what it reads - triple checked it

Charger IC, yes it's Bq735

Here's a pic, those to caps are shorted...

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

See attached. PS: TOPSIDE view.

With caution, measure the voltage of the highlighted pins of the charger IC.

Red meter probe to pin to test; black to ground.

REGN should be 6 volts.

ACDRV should be ~25 volts to enable the DCin mosfets. If not this value, power down and locate the ~4k resistor that is often mated to this pin and remove it. Do not lose the resistor but just remove it.

Then power up again and check if ACDRV is now ~25 volts.

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

ACDRV - 19,38v
ACOK - 1,019v
REGN - 6.03V

Without the 4k resistor ACDRV, as soon as I touch it with red probe reads 24v and immediately drops down to 19,38v

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

There should be a cap on REGN that is @ 6 volts. This cap is required to keep the charge pump working to deliver the ~25 volts for the ACDRV pin.

This cap on REGN may be defective. It is a 2.2uf (or higher) cap (going from memory here) and should be rated at 10V (to be safe) or higher. Perhaps worth replacing as a test.

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

It's 1uf 25V it seems to be ok, took it off and measured it. Maybe it's the actual IC charger that's at fault

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

The issue may be linked to the removed mosfet.

Can you confirm the following measurements?

1st Mosfet
Source & drain - 1,5 ohms
Source & gate - 231,10 ohms
Gate & drain - 232,8 ohms

2nd Mosfet - pads only
Source & drain - 133,5k
Source & gate - 240,7 ohms
Gate & drain - 133,6k

Again - very low resistance readings for source & gate - still this value ?

Source & drain on 1st mosfet is not a good value to have for a good mosfet.

Will check back later..need to buy a suit for junior..

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Same readings. I took out the IC Charger, and i can still see those caps shorting to ground.
After putting back the ic again same values

[Kambi13]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

Hi mon2, good news I was able to find the problem, it was a SOB of a 10uf cap that was bad in back of motherboard.

Incredible how such a small component can render useless an entire machine...

[mon2]

Re: Toshiba Satellite L50-A-122 Charger Light Pusling

SOB

Love it! Good job !!