Laptop repair help please

aliEnRIK

My girlfriends Toshiba L300 laptop just isnt playing ball

A week ago it wouldnt turn on and no power would even show when power supply plugged in
Then 10 mins later it buzzed into life
A few days went by and a similar thing happened but it took an hour to come to (And thats after id stripped it). I left it running for hours without a hitch.

Next day we came to it, it was dead! No lights come on or anything (Tried with charged battery in and out, power in and out and both in). Laptops stripped down to the motherboard. Dvd players out. Everything 'looks' fine. Ive wiggled things to see if wires are dodgy etc. I cant find anything.

Any ideas?

sharkie

looks like a capacitor problem, but which one? Sorry not much help. I would check that the voltage was being delivered to the chips and then the powergood signal and finally reset signal, but without a circuit diagram or knowing where to look......

sharkie

you have read this http://www.laptoprepair101.com/laptop/2006/01/28/toshiba-satellite-m35x-a75-power-jack-problem/

you are sure it is not a power issue?

aliEnRIK

sharkie wrote: »

you have read this http://www.laptoprepair101.com/laptop/2006/01/28/toshiba-satellite-m35x-a75-power-jack-problem/

you are sure it is not a power issue?

Ill have another look today, but it seems fine to me. But now that its looking like the motherboard, im going to start stripping it completely anyways, and doing everything I can in the process, including removing and resoldering the power link.
The power input on the L300 is different in that its a lead that then plugs into the motherboard. But it HAS been my favourite since the problem started, so ive got to resolder just to get it out of the way before looking at caps etc.

Hammyman

aliEnRIK wrote: »

The power input on the L300 is different in that its a lead that then plugs into the motherboard. But it HAS been my favourite since the problem started, so ive got to resolder just to get it out of the way before looking at caps etc.

The problem I've found with the outboard sockets is the earth contact becomes intermittent as its only a bit of bent metal. Never ever found it to be the connection at the motherboard end. If you look down the socket, you'll see the centre pin and the flat earth contact above. Shove in a miniature screwdriver and prise it down. You'll notice the charger plug gives more resistance the next time you plug it in.

aliEnRIK

Ive checked the lead that the charger plugs into with a multimeter and its fine. Powers getting through to the motherboard. Powers also in the battery which is directly linked to the motherboard. Neithers doing anything though

Its officially done my head in.

Hammyman

Sounds like the infamous "lead free environmentally friendly solder" dry joint issue that's resulted in more electronic gear ending up in landfill than the old solder ever did. Usual culprit is a dry joint on the chipset.

aliEnRIK

I tried to find a replacement motherboard online
Ive not found a single one thats identical to mine, but there are a load of faulty L300 motherboards on ebay. So looks like this happens quite a lot
Also, the motherboards are ridiculous prices, so looking like a new laptop is required

Electron_2

Hmmm, fault finding a motherboard without a circuit diagram and logic scope is no fun.

Try using a hot hair dryer blowing gently on the motherboard with power applied, if this kicks the lappy back to life then the problem is a thermally damaged component or a "dry joint" expanding back to life. Then use "freezer spray" to pinpoint the faulty part / area when the lappy dies.

Hammyman

Electron wrote: »

Hmmm, fault finding a motherboard without a circuit diagram and logic scope is no fun.
.

Heh-heh..my first job as a young trainee electronics engineer was that. I worked for Euromax Electronics. Being the videogame industry, they also scrubbed the chip numbers off and packaged the odd couple in a subboard which was then covered in black resin just to make it more fun.

I used to go home and go straight to sleep cos I was that mentally knackered.

Electron_2

Hammyman wrote: »

Being the videogame industry, they also scrubbed the chip numbers off and packaged the odd couple in a subboard which was then covered in black resin just to make it more fun.

I used to go home and go straight to sleep cos I was that mentally knackered.

Ah yes, the joys of reverse engineering.