Toshiba L500D not charging at bios

[sparker1]

Hi, I have a Toshiba L500D that will charge the battery if it is switched off. Once switched on it shows a solid battery light until it reaches bios and then it starts to flash orange but continues to boot to windows and loads the desktop. Then it shuts down soon after, depending on the amount of charge in the battery - even though it is plugged into the lab power supply. If I boot only to the bios it will also shut down if a battery is present even with lab supply.

When it gets to the desktop Windows advises that it is "plugged in ,not charging". I have tried a known working battery and get the same result. I have checked all mosfets for shorts in the charging circuit and they seem OK. I checked the large resistors and values seem OK. I'm not good at schematics but page 49 seems to be the charging circuit.

If I start the laptop without a battery it will shut down at the windows logo or loading windows desktop. If I stop it at the bios when only on lab power it will remain up indefinitely. It won't re-install windows from the Restore partition either as it also shuts down when loading windows.

Some research here suggests a mosfet is not working properly but I need help to know where to look. I have lots of spare boards for this model so any suggestions as to what to try and replace are welcome. Thanks for any help.

[sparker1]

Re: Toshiba L500D not charging at bios

I replaced PU4 and charging circuit is working and there are no boot problems. I suspect one of those el-cheapo chargers broke PU4 and the charger also burnt itself out (a lot of fried resistors in there).