Toshiba A300 - Tokin cap exchanged.

[PCManiac]

Greetings guys,

I got two toshiba A300 that were somewhat dead..
Changed both of their nec/tokin cap for 330 tantalum and they are working.
Altho, I would like to ask if some one has the boardview file of their board or if some one knows where can I buy it.

What they are doing from time to time, and I suspect is a charger fault, they turn the green light on. I press the button to turn the laptop on and it dies. The fan flickers and loses power.

I measured on the charger pins (the four pins, 2 red and 2 black) after the barrel plug and before turning it on I get a steady 19v on them. When I press the button, the voltage drops to around 11.5v and then raises back up when the mobo dies (I can listen some click when it cuts the source).

Am trying to understand for sure where the problem lies so I can tell the owner, if it needs more things or just the power brick.
Already redid the tantalum solders.

The board is a PT10G_6050A2171501_MB_A03. I fould some schematics for it but can't seem to find the boardview nor be sure they are the ones for my model since I don't know where to find the things..

Would appreciate your help even if only with suggestions.

Thank you.

[raajkumar]

Re: Toshiba A300 - Tokin cap exchanged.

I think this 330uf is not enough, because you have to install 4 caps but your photo say you just soldered only 3. add more caps and clean the motherboard soldered place. This problem is only with capacitors.

[String2016]

Re: Toshiba A300 - Tokin cap exchanged.

Just put 4 to 5 tantalum caps

[dmartins]

Re: Toshiba A300 - Tokin cap exchanged.

Carissimo , mete 4x 330uF e fica Ok !
Cumprimentos

I was saying to this guy in our language to install 4x 330uf tantalum caps

[PCManiac]

Re: Toshiba A300 - Tokin cap exchanged.

Thank you all for your suggestions.
Will do so!

I have read in other forums that 3 were enough and, to be honest, that's all I had laying around. Have to get another dead laptop donor board for those haha.

Thank you/ Obrigado.

[PCManiac]

Re: Toshiba A300 - Tokin cap exchanged.

Greetings,

I have added the fourth cap and, still the same.. :\

any other suggestions?

[shuc]

Re: Toshiba A300 - Tokin cap exchanged.

This is what I do... and works fine.

[gabiz_ro]

Re: Toshiba A300 - Tokin cap exchanged.

Test with another good working charger.

Where you here click when it cuts the source? Motherboard or charger?

[ktmmotocross]

Re: Toshiba A300 - Tokin cap exchanged.

caps fault is that laptop restarts in LOAD

u have short in some powerswitched rails.

[rievax_60]

Re: Toshiba A300 - Tokin cap exchanged.

I had a problem something like that in an A200. I found a shorted High Side MOSFET in the CPU VCORE regulator.

[PCManiac]

Re: Toshiba A300 - Tokin cap exchanged.

Thank you all for your input.

Shuc - At first I tried that, unfortunately I wasn't able to do it so read some where in the forum that the center was negative as well and I could scrape the insulation off it.

Gabiz_ro - I listen the click on the motherboard side.

ktmmotocross - it has been running under load for the last 4/5 hours with no reboot. Still think it's a power source issue.. gotta try to get one to test.

rievax_64 - Mind trying to explain me which ones are the vcore mosfet? Gotta google how to test *fets later on.

Thank you all.

[ktmmotocross]

Re: Toshiba A300 - Tokin cap exchanged.

Thank you all for your input.

Shuc - At first I tried that, unfortunately I wasn't able to do it so read some where in the forum that the center was negative as well and I could scrape the insulation off it.

Gabiz_ro - I listen the click on the motherboard side.

ktmmotocross - it has been running under load for the last 4/5 hours with no reboot. Still think it's a power source issue.. gotta try to get one to test.

rievax_64 - Mind trying to explain me which ones are the vcore mosfet? Gotta google how to test *fets later on.

Thank you all.

thats what i wrote. u dont have problem with tokin cap.
check resistance of all big coils on board. u have short somewhere

[rievax_60]

Re: Toshiba A300 - Tokin cap exchanged.

Q17 and Q18 are the high side MOSFETs.

[PCManiac]

Re: Toshiba A300 - Tokin cap exchanged.

Thank you guys.

ktmmotocross: Which ones are those coils you talk about and how to measure them?

rievax_60: checked those with no shorts found. Took the time to test 12 and 21 as well as I was at it since some one said in another post that those could be troubles as well...

[ktmmotocross]

Re: Toshiba A300 - Tokin cap exchanged.

check its resistance to ground and all big grey coils

[rievax_60]

Re: Toshiba A300 - Tokin cap exchanged.

Thank you guys.

ktmmotocross: Which ones are those coils you talk about and how to measure them?

rievax_60: checked those with no shorts found. Took the time to test 12 and 21 as well as I was at it since some one said in another post that those could be troubles as well...

With the high side MOSFETs, check carefully for Drain to Gate leakage.
The low side MOSFETs can not be checked in circuit unless the CPU is removed. I have never seen low side MOSFETs fail anyway.

[gabiz_ro]

Re: Toshiba A300 - Tokin cap exchanged.

From what I understand,laptop works fine,only sometimes when you hit power button,laptop start-up,fan also,voltage from charger drops from 19V to ~11.5V,board make a click noise and shut down,voltage from charger rise back to 19V

Checking boards for shorts have low rate of success since most time laptop power up and work fine,so you'll not find any short.

In event of short on some power rails,you must be lucky to find it since is not permanent,appears only some times in some conditions.

You may try to monitor all power rails in same time and see which one cause this.

[PCManiac]

Re: Toshiba A300 - Tokin cap exchanged.

I will keep this on hold till I get my tantalum caps and solder them to make sure am not missing anything.

Thank you all

[PCManiac]

Re: Toshiba A300 - Tokin cap exchanged.

Hey guys, just a quick update on this.

These two laptops were fixed successfully after I got my tantalum and are working as happy ever since then.
One of them had as well a bad PSU, which was what was causing the sudden shutdowns and not powering on.

Thank you for your help.

Thank you all