Toshiba A300 strange problem and Nec Tokin

[redstrat984]

hello
my laptop show a strange problem....
when i try to turn on, the laptop start only for half second....
the led blinking for a flashing moment and all turn off....
in this very short time, the fan and the hdd never turn on....
if i plug the adapter to recharge the battery, te recharge work perfectly.
this problem is present whit battery and whit AC adapter, whit battery only, and whit ac adapter only.....
i've tryed to change nec tokin whit normal electrolitic caps to make a test whit no result...
now i've ordered smd cap but o don't know if i can resolve the problem only whit this cap...
i've tryed to put out ram, video card, wifi,bluetooth and motherbord from case whit no cable wired.

any idea?

thanks.

[ktmmotocross]

Re: Toshiba A300 strange problem and Nec Tokin

shorted some of power rail. maybe gpu.

[redstrat984]

Re: Toshiba A300 strange problem and Nec Tokin

i've tried to put out video card and start pc, but no result....same problem....

what can i do to identify the short?

[ktmmotocross]

Re: Toshiba A300 strange problem and Nec Tokin

measure resistance of coils/capacitors

[redstrat984]

Re: Toshiba A300 strange problem and Nec Tokin

in motherboard or video card?

[redstrat984]

Re: Toshiba A300 strange problem and Nec Tokin

So... how can i test to indentify shorted caps?

[redstrat984]

Re: Toshiba A300 strange problem and Nec Tokin

i've made another test...whit no results

i've totaly disassembled the laptop..
i've tried in order
to turn on the motherboard only whitout all component,
whitout cpu there'isnt any led and no sign of life....
insering the cpu, the ac led turn on, but when i press on/off button the sign is the same..... all led flash for a little moment whitout fan start, and after a moment all light turn of immediatly.
i've tested all whit and whitout ram(4 different bank)...no results....same problem.....
whit and whithout ati video card.... same sign....
i'm not able to do a caps test....
what can i do.....?

please help.....

[redstrat984]

Re: Toshiba A300 strange problem and Nec Tokin

i've just maded some test to try to debug this motherboard....i've maded some misure to varius Q and U component end misureted some PAD place....
PAD3 - 0v
PAD4 - 0v
PAD6 - 0v
PAD7 - 0v
PAD8 - 5.09v
PAD9 - 19.2v
PAD10 - 19.2v
PAD11 - 3.39v

Q801
Pin 1-2-3 19.2v
Pin 4 12.8
Pin 5-6-7-8 19.2v

Q802
Pin 1-2-3-4 19.2v
Pin 5-6-7-8 0v

Q803
Pin 1-2-3-4 0.18v
Pin 5-6-7-8 19.2v

Q804
Pin 1-2-3-4 0,18v
Pin 5-6-7-8 0v


U24
Pin 1 3.56v
Pin 2 GND
Pin 3 2,5v
Pin 4 5.09v
Pin 5 5.09v

Q36
Pin 1-2-4-5-6 3.38v
Pin 3 0v


Q33
Pin 1 3.39v
Pin 2 0v
Pin 3 0v

Q34
Pin 1 3.38v
Pin 2 0v
Pin 3 0v

Q41
Pin 1-2-3 0v
Pin 4 0.18v
Pin 5-6-7-8 3.39

Q39
Pin 1-2-3 3.38v
Pin 4 3.41v
Pin 5-6-7-8 19.2v


Q32
Pin 1-2-3-4 5.09v
Pin 5-6-7-8 19.2v


Q29
Pin 1-2-3-4 0v
Pin 5-6-7-8 5.09v


Q20
Pin 1-2-3-4 0v
Pin 5-6-7-8 19.2v

Q19
Pin 1-2-3-4-5-6-7-8 0v

Q28
Pin 1-2-3-4 0v
Pin 5-6-7-8 19.2v

Q31
Pin 1-2-3-4 0v
Pin 5-6-7-8 0v

Q17
Pin 1-2-3-4 0
Pin 5-6-7-8-9 19.2v

Q12
Pin 1-2-3-4 0v
Pin 5-6-7-8 0v

Q18
Pin 1-2-3-4 0
Pin 5-6-7-8-9 19.2v

Q21
Pin 1-2-3-4 0v
Pin 5-6-7-8 0v


i need help....