Toshiba P855 only works with battery

[zioricci]

Hi,

I have a Toshiba satellite P855 that was previously stuck on the Toshiba logo and I couldn't enter the BIOS with F2 and then, thanks to the 2 original bios files that hardware1 gave me, yesterday I was able to boot it up to Windows 11. I deduced that the fault was the corrupted bios. So all the hardware works, hard drive, graphics card, RAM etc. The problem is that everything works if I power it with only the main battery, as soon as I take it out and put the charging cable in, the laptop, although it always succeeds entering bios with F2, hangs on Toshiba logo. I tried doing the CMOS reset but nothing changed, I tried putting a discharged main battery that can no longer be recharged, thinking that the battery was the go-between, and after the Toshiba logo I get a row of pixels at the top of the screen and nothing more. Here, these are the symptoms, so in summary ... with the main battery Windows starts and all the hardware works, while with the cable the laptop does not even finish the POST phase. What can it be ?

Thanks you

[mon2]

Re: Toshiba P855 only works with battery

See attached.

Attach the official power adapter. For now, disconnect the battery.

Meter in DC volts (20V or higher is ok) mode.

Carefully measure the voltage to ground of the charger IC pins of interest.

Start with:

ACN
ACP
ACDRV
REGN
VCC
ACOK

Post each measurement.

[zioricci]

Re: Toshiba P855 only works with battery

See attached.

Attach the official power adapter. For now, disconnect the battery.

Meter in DC volts (20V or higher is ok) mode.

Carefully measure the voltage to ground of the charger IC pins of interest.

Start with:

ACN
ACP
ACDRV
REGN
VCC
ACOK

Post each measurement.

Voltage power adapter 19.30 V

ACN 18.50 V
ACP 18.50 V
ACDRV 24.23 V
REGN 6.08 V
VCC 18.16 V
ACOK 3.35 V

Edit:
I want to try again, it doesn't add up that ACP and ACN have the same voltage



With Power Adapter 20.06 V no load, the exact values are as follows:

ACN 19.85 V
ACP 19.86 V
ACDRV 25.66 V
REGN 5.88 V
VCC 19.64 V
ACOK 3.36 V

[mon2]

Re: Toshiba P855 only works with battery

These are all good readings.

ACN should be very close / equal to ACP. This is the voltage going IN and OUT of a local current sense resistor. The charger IC will monitor BOTH pins and measure the very small voltage drop to gauge the current consumption of this power rail.

With the posted details, the ACDRV pin is being boosted OK to ~25 volts so the 2 x DCin mosfets are being enabled.

The next suggestion is to proceed to measure all of the pins on this charger IC. This is to review what exactly the charger IC is reading when the power adapter is mated to the logic board.

Post the list with the pin numbers of the charger IC for a review.

[zioricci]

Re: Toshiba P855 only works with battery

These are all good readings.

ACN should be very close / equal to ACP. This is the voltage going IN and OUT of a local current sense resistor. The charger IC will monitor BOTH pins and measure the very small voltage drop to gauge the current consumption of this power rail.

With the posted details, the ACDRV pin is being boosted OK to ~25 volts so the 2 x DCin mosfets are being enabled.

The next suggestion is to proceed to measure all of the pins on this charger IC. This is to review what exactly the charger IC is reading when the power adapter is mated to the logic board.

Post the list with the pin numbers of the charger IC for a review.

ACN 19.85 V
ACP 19.86 V
ACDRV 25.66 V
REGN 5.88 V
VCC 19.64 V
ACOK 3.36 V

on the other pins the values are

3 = 19.86 V
6 = 3.36 V
7 = 0.22 V
8 = 3.36 V
9 = 3.36 V
10 = 0.67 V
11 = 3.16 V
12 = 3.16 V
13 = 3.16 V
14 = 0 V
15 = 0 V
17 = 5.89 V
18 = 3.16 V
19 = 3.16 V

[mon2]

Re: Toshiba P855 only works with battery

Need to run but at a quick glance - looks good on the charger IC. Remove all power and review the many threads in this forum re: shorted mosfets. Read the thread by @Piernov above on charger ICs.

In summary, there must be a leaky mosfet that is fighting between the main DCin power path and the battery mosfet.

Often, the 2nd DCin mosfet driven by the ACDRV signal is leaky. You can confirm this condition by checking the resistance of each mosfet.

Check:

source & drain
source & gate
gate & drain

Checking for a low resistance which on a mosfet is bad. Often will be a defective component.

Remove all power / battery and then check the resistance of each mosfet that is surrounding the charger IC.

Download the charger IC datasheet and review a typical configuration of how TI wants the engineer to apply the chip. Yours will be 99.999% the same.

Post the measurements...

[mcplslg123]

Re: Toshiba P855 only works with battery

Does it have NEC-TOKIN type capacitor in cpu vrm circuit?

[zioricci]

Re: Toshiba P855 only works with battery

Does it have NEC-TOKIN type capacitor in cpu vrm circuit?

If you're referring to this genre,

no it doesn't have it and if you ask It me about the row of pixels, it's gone for the moment. In this regard I would like to ask a question: did it disappear because I changed from CSM boot to UEFI or because I soldered some choke coils

that were missing on the hdmi port?

[zioricci]

Re: Toshiba P855 only works with battery

Need to run but at a quick glance - looks good on the charger IC. Remove all power and review the many threads in this forum re: shorted mosfets. Read the thread by @Piernov above on charger ICs.

In summary, there must be a leaky mosfet that is fighting between the main DCin power path and the battery mosfet.

Often, the 2nd DCin mosfet driven by the ACDRV signal is leaky. You can confirm this condition by checking the resistance of each mosfet.

Check:

source & drain
source & gate
gate & drain

Checking for a low resistance which on a mosfet is bad. Often will be a defective component.

Remove all power / battery and then check the resistance of each mosfet that is surrounding the charger IC.

Download the charger IC datasheet and review a typical configuration of how TI wants the engineer to apply the chip. Yours will be 99.999% the same.

Post the measurements...

The ACDRV is the gate of PQ204 and do you think it could be the mosfet that could create this problem? When I had measured it with the multimeter it was not shorted and I also had the threshold voltage by reversing the test leads. However, I will repeat in a while the measures you mention. Thanks for your help

[mon2]

Re: Toshiba P855 only works with battery

Remove all power. Meter in resistance mode.

Check the resistance of the high side mosfet at PQ201.

Also check the same detail of the battery mosfet at pq205.

Post each list of measurements.

Source (1-2-3) & drain (5-6-7-8)
Source (1-2-3) & gate (4)
Gate (4) & drain (5-6-7-8)

[zioricci]

Re: Toshiba P855 only works with battery

Remove all power. Meter in resistance mode.

Check the resistance of the high side mosfet at PQ201.

Also check the same detail of the battery mosfet at pq205.

Post each list of measurements.

Source (1-2-3) & drain (5-6-7-8)
Source (1-2-3) & gate (4)
Gate (4) & drain (5-6-7-8)

For pq201, in diode mode, no short and the threshold is there, 0.51 V

in resistance mode:

Source-drain : 8Mohm
Source-gate: infinite
Gate-drain : infinite



For pq205, in diode mode, no short and the threshold is there, 0.52 V

in resistance mode:

Source-drain : infinite
Source-gate: infinite
Gate-drain : infinite

[mon2]

Re: Toshiba P855 only works with battery

Is the battery attached or disconnected?

When you checked the charger IC pins, was the battery connected or disconnected?

What is voltage to ground of the battery?

[zioricci]

Re: Toshiba P855 only works with battery

Is the battery attached or disconnected?

I removed all power supplies as you told me to do, I also removed the RTC.

When you checked the charger IC pins, was the battery connected or disconnected?

disconnected

What is voltage to ground of the battery?

0V. Are you asking me for some short/leakage current ?

[mon2]

Re: Toshiba P855 only works with battery

Does the removed battery have enough charge to power the logic board?

If yes, remove the adapter and connect the battery.

Then power on and measure the charger IC pins again.

Measure at the charger pins so we can review exactly what the charger IC is reading.

Also interested in the voltage to ground readings of the DCin mosfets while powering with the battery only.

[zioricci]

Re: Toshiba P855 only works with battery

Does the removed battery have enough charge to power the logic board?

If yes, remove the adapter and connect the battery.

Then power on and measure the charger IC pins again.

Measure at the charger pins so we can review exactly what the charger IC is reading.

Also interested in the voltage to ground readings of the DCin mosfets while powering with the battery only.

ADAPTER ----------->BATTERY (11.10 V)

ACN 19.85 V------>10.99
ACP 19.86 V------>10.97
ACDRV 25.66 V------>25.66
REGN 5.88 V------>0
VCC 19.64 V------>10.5
ACOK 3.36 V------>0


on the other pins the values are

3 = 19.86 V------>0.02
6 = 3.36 V ------>0
7 = 0.22 V------>0
8 = 3.36 V ------>3.32
9 = 3.36 V ------>3.32
10 = 0.67 V------>0.67
11 = 3,16 V------>16.98
12 = 3,16 V ------>10.8
13 = 3,16 V------>10.8
14 = 0 V------> 0
15 = 0 V------> 0
17 = 5,89 V ------>10.40
18 = 3,16 V------>10.65
19 = 3,16 V------>10.65


PQ204 drain 11.08 V
PQ203 all 0V

[zioricci]

Re: Toshiba P855 only works with battery

I put the arrows to separate otherwise attacked everything

[mon2]

Re: Toshiba P855 only works with battery

To confirm, the LEFT side of the table is with the ADAPTER ONLY.

Right side of the table is with the BATTERY ONLY?

ACDRV 25.66 V------>25.66

ACDRV remains @ ~25v with only the battery connected?

[zioricci]

Re: Toshiba P855 only works with battery

To confirm, the LEFT side of the table is with the ADAPTER ONLY.

yes

Right side of the table is with the BATTERY ONLY?

yes, left side adapter only and right side battery only

ACDRV remains @ ~25v with only the battery connected?

my mistake, ACDRV with battery only is 0V

[zioricci]

Re: Toshiba P855 only works with battery

Today I noticed that the battery usually reaches more than 12V, now it's 11.16V but the charge indicator is off and not charging even though windows says it's 100% charged, while with a completely empty battery the indicator turns on.

[zioricci]

Re: Toshiba P855 only works with battery

Now it's loading... I'm writing from Toshiba but powered by battery, with the adapter acting as a charger and not as a power supply