Toshiba C850 only wants AC power

[sparker1]

Re: Toshiba C850 only wants AC power

I'll measure it again and get back.

Sorry for the delay. Battery terminals show 2.86 volts. The battery charge light is blinking (normal). It still won't boot whenever a battery is present. Tried a new battery and no luck. There is a FDMC8884 (N channel Power trench mosfet) that is listed as being for - High side in DC - DC Buck Converters, Notebook battery power management, Load switch in Notebook. I can't get a schematic. Is it possible this could be the problem IC? It's hard to get a probe in there.

[Tuomo]

Re: Toshiba C850 only wants AC power

Sorry for the delay. Battery terminals show 2.86 volts. The battery charge light is blinking (normal). It still won't boot whenever a battery is present. Tried a new battery and no luck. There is a FDMC8884 (N channel Power trench mosfet) that is listed as being for - High side in DC - DC Buck Converters, Notebook battery power management, Load switch in Notebook. I can't get a schematic. Is it possible this could be the problem IC? It's hard to get a probe in there.

a few things that could explain the problem at Battery present no boot.

1. AC Voltage go directly to Battery.

2. Keyboard controller is broken.

3. Something else?

[sparker1]

Re: Toshiba C850 only wants AC power

I might try and replace the FDMC8884 and see what happens. It'll take a long time to get one. The keyboard works fine .

[Tuomo]

Re: Toshiba C850 only wants AC power

I might try and replace the FDMC8884 and see what happens. It'll take a long time to get one. The keyboard works fine .

Keyboard controller is bit misleading name to this chip

Those 3.3V voltages from Battery connetor go to KBC chip etc...

If FDMC884 replacing not help, you can check what is your motherboard manufacturer ( quanta? ).

Same manufaturer has very similar schematic even componet name are different.

[sparker1]

Re: Toshiba C850 only wants AC power

Keyboard controller is bit misleading name to this chip

Those 3.3V voltages from Battery connetor go to KBC chip etc...

If FDMC884 replacing not help, you can check what is your motherboard manufacturer ( quanta? ).

Same manufaturer has very similar schematic even componet name are different.

I didn't know that. Thanks and I'll remember it for the future. However, now I'm a bit embarrassed over the whole thing. After spending all this time checking for shorts, bad fets, checking voltages, ram, searching high and low for a schematic and begging for help here it turns out to be a scrambled BIOS. Yesterday I did an update on one of the mother boards and now everything works fine. All 3 motherboards were "refurbished" in China and all had the same problem. I think something must have happenned to the BIOS when the repair process took place. I hope this helps somebody else. Thanks to all that tried to help. I think I'll hide away from here for awhile now.

[saxonas]

Re: Toshiba C850 only wants AC power

Sorry for the delay. Battery terminals show 2.86 volts. The battery charge light is blinking (normal). It still won't boot whenever a battery is present. Tried a new battery and no luck. There is a FDMC8884 (N channel Power trench mosfet) that is listed as being for - High side in DC - DC Buck Converters, Notebook battery power management, Load switch in Notebook. I can't get a schematic. Is it possible this could be the problem IC? It's hard to get a probe in there.

Hi!i have the same motherboard.Laptop doesnt power on with adapter and doesnt charge the battery but it will power on from a charged battery.

The FMDC8884 on my board doesnt give any V .The other big mosfet next to it.Gives me 19V from its one side.The other side is 0 V.

I would also like to try to update bios.Is it possible provide me a link with the bios you have installed.

[shelby5041]

Re: Toshiba C850 no power

Hi!i have the same motherboard.Laptop doesnt power on with adapter and doesnt charge the battery but it will power on from a charged battery.

The FMDC8884 on my board doesnt give any V .The other big mosfet next to it.Gives me 19V from its one side.The other side is 0 V.

Is this ok?