Toshiba L300D-13S intermittent boot

[spleenharvester]

Got one of these today, thought it would be a Tokin case, it's not.

Battery is completely dead and shows signs of water damage. When powered it will most of the time just show a blackscreen, then power off again, then repeatedly cycle on and off.

Occasionally it will boot but ask for a password - pretty sure one wasn't set, which points to a BIOS issue.

Thing looks like it's been run over by a truck and the fan sounds like a chainsaw so I wouldn't be surprised if there's majorly something wrong though. I'll post back with voltages etc in a bit.

Anyone had similar troubles?

[goontron]

Re: Toshiba L300D-13S intermittent boot

yuck!! post pics to! the fan not running right could have cooked something partly that would explain some of the problems

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Turns out the fan just had a bit of hay in it. Something really odd about this laptop - it doesn't appear to have been opened before, seals are still intact and stuff, but inside it's a mess. Snapped bits of plastic, bits of wood and hay, missing screws, board isn't fastened at all at the top. Not sure what's going on here :p

Anyway, I tried to clear CMOS to remove the BIOS password. On first boot I got into BIOS setup. After that it started asking for a password again. I'm very definitely swaying towards a BIOS issue here. Three odd things:

1) when it powers up with no display, it is still very responsive to the power button, as if it were POSTing.

2) I accidentally shorted a 19v source on the board and got a spark. This didn't even shut the laptop down - it just carried on running while in BIOS setup. I was testing a MOSFET in this area that has odd colouring on it - maybe this is the fault?

3) USB keyboard powers up but does not function. Works fine on other L300s. 5v, 3.3v voltages are present.

I'd really like to get into DOS to try and flash this thing but I can't get past this stupid password screen on the odd time it does work.

I've pressed down on the BGA chips while booting and it's made no difference so it doesn't seem to be a BGA problem.

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Some more progress, that discoloured looking MOSFET on closer inspection appears to be partially melted. When the laptop boots without display, voltage on the adjacent testing pad remains at 19v. When it boots and POSTs, voltage on this pad is pulled low to 10.35v. I have an identical motherboard so I'm going to replace the MOSFET when I get time and see if it fixes.

Need to tackle this BIOS password issue now though. It won't respond to a CMOS reset.



^There's the schematic, the MOSFET (Q17) is highlighted. Seems to tackle the +V5A rail. It looks to be working on DMM but is very definitely melted on one side so I'm guessing it is the cause.

[goontron]

Re: Toshiba L300D-13S intermittent boot

if q17 is working correctly sometimes but not others then yes it would cause startup issues. i would also check for any resistors that could have cooked it or vice versa, also there is still a chance that the Tokin is bad and maybe could have cooked q17 along with it.

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Thankfully there's no Tokin on this laptop, seems to be the case for all AMD-based L300s from what I can tell.

I've figured out it will boot when warmed up fine but will not from cold. Still pretty sure it's not BGA-related because, well, that MOSFET still looks pretty damn cooked. I'd get a pic but my camera is too shoddy to focus on it. If replacing the FET doesn't work I'll probably move onto the tantalums because they get pretty warm.

I've also finally managed to remove the CMOS password. Unplugged everything except adapter, added one stick of RAM to innermost slot, bluetacked some wire across the B500 jumper and started it. After a few attempts it came on and off a few times during boot and then the password was gone!

[goontron]

Re: Toshiba L300D-13S intermittent boot

if you heat q17 with a hair dryer from after its been off for a while does it post with a screen?
either way q17 is not healthy and needs to be replaced, but this test is to verify its not another component causing a problem too.

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

I'll let it cool down and give it another try.

Even if it doesn't I'll replace either way. Pretty sure I have 3 or 4 of these exact fets on scrap boards.

<ignore this, for my own reference: exact fet is Q19 on L300D-10Q board)

[goontron]

Re: Toshiba L300D-13S intermittent boot

let me clarify that. heat q17 after the board has cooled,if you get post screen then q17 was the fault,if not it will require more trouble shooting. but you still want to replace q17 to avoid problems.

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Replaced Q17 with identical replacement, cleaned out all the dust bunnies and changed the board into a case that doesn't look like it's been run over by a bus.

Not a single unsuccessful boot I could be speaking too soon but it appears to be sorted!

Cheers buddy, much appreciated!

[goontron]

Re: Toshiba L300D-13S intermittent boot

no problem. nice to see what i consider a good laptop fixed! but did you replace the fan mate?

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Nah I took the metal casing off, slid the blades off, and gave it all a blast with compressed air. Turned out it was a massive ball of dirt skimming the fan blades. Good as new now!

[goontron]

Re: Toshiba L300D-13S intermittent boot

good! glad to hear it works out. cheers mate

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

This one's developed an odd problem now. :/

It can sit for hours and hours in windows recovery or BIOS without a problem. But as soon as it boots into Windows, a few seconds after the cursor appears, the HDD powers down - and shortly after that, the laptop hard powers off.

Safe mode doesn't work, low res mode doesn't work, last known good config doesn't work.

What could be causing this? Faulty ceramic cap on the audio board or something? I'm wondering if maybe I need to improve the solder joints on the replaced MOSFET.

Cheers

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Okay found the problem guys, used a magnifying glass and found a tiny tin whisker (I presume from the desoldering braid) shorting two legs of the MOSFET. Boots into Windows fine now. Cheers!

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Bump, another odd problem with this one. Sometimes when you power it on, everything fires up, but black screen and no POST. In order to make it continue, you have to tap the power button again and then it all works fine?

Reckon a BIOS update could fix it? It's on 1.3 and I think the newest is 1.8.

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Bump for anyone with the same problem, Bios V1.8 has completely fixed the issue.

[spleenharvester]

Re: Toshiba L300D-13S intermittent boot

Another bump, the board came back today, it died and took a stick of RAM and the CPU with it. Fault is in the same area, missing +19v on that mosfet and missing +5v HDD power. Think it might be best going to the scrap bin.