Toshiba C875 runs on battery but not adapter

[paul1149]

Hi folks,

I've got a 17" Toshiba C875-S7304 laptop. It's motherboard is a:

Hannstar J MV-4 94V-0 :239
E89382
PLF/CSF/CSR UMA MB

It's close to the board in this thread: https://www.badcaps.net/forum/showthread.php?t=28897, which is a PLF/CSF/CSR DSC MB but in places it almost seems to be a mirror image of the pics there.

I'm not good at this stuff, so probably I'm looking for general guidance and a idea of how hard it would be to fix this.

If I place a good battery into the unit, it will run on the battery. With a dead battery, or no battery, the DC line-in will not power the unit at all. No neon lights, nothing. Oddly, though, when I place a charged battery into the machine, with the DC-in line attached, the orange charging light comes on.

I tested the voltage and found that the laptop's external remote DC jack is delivering full voltage to the MB DC input jack. My guess is that something on the MB prevents that voltage from reaching and charging the battery. Perhaps a blown fuse.

No idea how to proceed, or if I should try. I'm going to attach some board shots.

Thanks,
Paul

[paul1149]

Re: Toshiba C875 runs on battery but not adapter

One more clue. When booted into Win8, with the adapter connected the battery shows it's charging, but it isn't. I updated the BIOS and reloaded the Windows battery driver, but the battery is still losing steam. Evidently the MB sees the adapter, and thinks it's charging the battery, but it's not happening.

[Djosla]

Re: Toshiba C875 runs on battery but not adapter

please check this mosfet,i find it shorted a lot of times

[paul1149]

Re: Toshiba C875 runs on battery but not adapter

Thanks, I don't see anything visually wrong with that element, and don't know what further to do about it.

I did probe around. In the attached photo, the element circled in red attracted my attention. Is it a fuse? Because my theory is that a power surge burned out the adapter input circuit.

All the elements circled in blue had +19 volts at both ends. The element in red had 19v at its end near the power block, and 0v at its other end. The element circled in black registered 0v.

I shorted across the element in red while the adapter was plugged in, with no battery, and got a spark.

[Djosla]

Re: Toshiba C875 runs on battery but not adapter

no it`s not fuse,it`s capacitor,you have probably made more damge now... element marked with Q is fuse...and you can`t just short elements by filing...
Mosfet i marked was probably your problem,now you should check all components on the picture...

[paul1149]

Re: Toshiba C875 runs on battery but not adapter

It didn't seem to suffer further damage, thankfully. But I decided to part the machine out. This problem is beyond my abilities. Thanks.

[Djosla]

Re: Toshiba C875 runs on battery but not adapter

...

[newtothis]

Re: Toshiba C875 runs on battery but not adapter

Shorting things out when having no idea what they are, Yeah best it was parted out before it was set on fire!