Toshiba Tecra A40-G-138 (FUZ2SY1 A4607A) not charging

[Avinitlarge]

Does anyone have a schematic for a Toshiba Tecra A40-G-138 (FUZ2SY1 A4607A motherboard)?
It's not charging through USB C, the mosfet was dead, I've replaced it but still not working. The charger is putting 20v out and the laptop is showing it's charging so it's partially working.

The original mosfet was a AON7422G, I’ve replaced it with a AON7430 which is a similar spec


Thanks

[mon2]

Link a schematic, if available but inside the dedicated schematic forum only.

The 20v confirms the pd controller is working ok. The low current draw of 60 mA confirms there is a power path problem to the main power rail. Which battery charger IC is onboard? Share pics and full topside markings of the charger IC. The fault is between this region and the PD controller's VBUS.

Hunt as to how far the 20v travels onto the board.

[Avinitlarge]

After replacing the mosfet, it did work briefly, 20v @ 1.57a.
I’ve traced the voltage and it goes all the way to a mosfet, it charges fine using the barrel port, this goes to the mosfet next to the one for USB C charging. It uses a isl9241 which I believe controls the PD. I’ll get some pictures later today.

[Avinitlarge]

I have a feeling is may be down to the MOSFET I’ve used, I switched them around and it stopped charging from the barrel connector.

[mon2]

If you suspect the mosfet(s) -> remove all power. Meter in resistance mode.

Measure the resistance across the mosfets:

source / drain
source / gate
gate / drain

Post each measurement. Each measurement must be hundreds of k ohms or higher if the part is ok. Otherwise, the part may be defective. Next suggestion is to flux and remove any suspect and then measure it again while the part is off the board and on your work table.

[ghedada.06]

toshiba tecra z50-c-138 when i plug the charger (bench power supply) the power led comes up automatically with no display without pressing power button and i see current consumption of 0.25amp to 0.30amp. all the voltages are present except cpu votage
i tried to turn on the laptop using an ac adapter and injecting voltage on cpu coil but nothing changed

[mon2]

Be careful of voltage injection at wrong locations or with the wrong values. Injection is usually used to hunt out shorted parts.

Remove all power. No battery. What is the resistance to ground of the vcore cpu rail?

[ghedada.06]

mon212ohm

[ghedada.06]

mon2 to give you a clear idea about this laptop. this laptop came in usb port replacement from another computer shop, i made a mistake because i replaced the usb ports from a donner board (toshiba c50) without testing the laptop first and the computer shop didn't test it also (that was dumb from us) now the laptop turns on without me pressing power button and seems like vcore is missing

[mon2]

Does this unit allow for a normal barrel type charger feed to power the board? If not, do not use an external power supply. Remain to use the usb c adapter only. The power delivery controller is working since you have 20v but the current draw is low because some power path is not fully on. Still need to hunt for the charger ic which you mentioned may be the isl9241? Study if onboard. Check voltage to ground of each inductor. Bios is powered? Maybe bios is corrupted? Backup the original and reflash this flash device. Inject only 1 volt max if you must and confirm the cpu / pch does not heat up.

[Avinitlarge]

It has a barrel connector as well as the USB C, the barrel charging is fine. I’m going to look at it again after the new year. I was hoping to get it working so I don’t have to take multiple chargers with me.

[mon2]

Share quality pics of the USB C area (top and bottom side of the board). Need more details on who the PD controller is which appears to be working since 20v is being selected. Next that follow this logic will be mosfets that enable / disable before reaching the charger IC. The fault is between the PD controller output and the charger IC which selects if the USB C or the barrel connector are the power source.