Serious problem with my Toshiba laptop

i have a serious problem with my toshiba laptop model no L300 ST2501 which i owned for over 1 1/2 years now...the problem come during start up..

when i'm about to start my laptop with ac power only, i noticed that the power supply LED is falshing and i hear sound of cooling fan also..

and suddenly it went off and on and repeatly doing that..but when i try using the battery only,,it work just fine..and it never freeze or hang up..

so the situation is i had to start my laptop using the battery first and after all loading up i plug it with power cord after a few times of trying..after few days i had send my laptop for repair since it already passed the warranty period..the tech guy told me that i had a problem with my motherboard (i.e shortcircut motherboard) but i not so sure because everytime when my laptop working fine i was able to play games like counterstrike and warcraft without hang or freeze...and i test all my hardware such DVD drive, card reader, USB ports and wireless ports..all working just fine even i post this massage using this laptop..if someone can tell me any advise or opinion regarding this i really appreciate..this thing only happen during start up...all the rest just fine...
 
Sometimes that Toshiba model has the "Jack" for the power plug disconnected ,or broken away,from the system board and must be soldered back on. It is a "flat soldering technique" that few can do... so look for a repair shop or a skilled electronics guy who really knows his solder. The solder must be applied with a special soldering iron that is instant on and instant off... causing very high heat that allows the solder to flow under the jack quickly like water would do.

There are not many technicians good at it, and those that are not good at it can make it worse and unrepairable... So the cost is high, and sometimes it is simply easier to replace the system board.

Of course it could be another issue, but we see this on a lot of Toshiba and Sony laptops
 
dear raybay...

i already take a look with help from my friend for the thing that you say but i dont find any problem with my internal power jack..it still tight on its places and not loose..theres no crack also on the board..and using a special magnifying glass we look throughout the mother board and find nothing fried up...but before all that. i have downloaded a HOT CPU TESTER PRO 4 LITE EDITiON which i get from this website and i run a test with full load on system for 6-7 hours without any hang or freeze..after reassemble back all things and start again with same situation as my post...i run again and get the same result...this really give me a headache for what going on with my laptop as i also dont get any respon from toshiba tech support with the same post.....
 
It would seem your only choice is to have a good tech evaluate it...
The greatest fault of Toshiba is their long repair time, and they use contract repair folks, but that might be your best hope... Count on $65 plus shipping though... and it might be time to replace it.
 
I have similar problem in satellite L300 model

Disable processor may solve your problem

for boot in safe mode, restart your laptop and keep tapping F8 key until a list of booting option appear
>> choose start window with safe mode
>> go to device manager
>> go to processor right click mouse and disable
>> restart the laptop (normal startup).
 
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