toshiba satellite c55-b

[mohammed aram]

hi everybody
i have aboard of toshiba da0blimb6f0
there is no schematics for this
and the lap power dead
there is 5 v and 3.3 v
any suggesion??

[bachir2004]

Re: toshiba satellite c55-b

is this your motherboard?

[piernov]

Re: toshiba satellite c55-b

No his moterboard is Quanta BLI, schematics not available.
Nothing after pressing power button? 3.3V on power switch?
Check resistance of R391 (0ohm), and its resistance to ground (on both sides).

[mohammed aram]

Re: toshiba satellite c55-b

No his moterboard is Quanta BLI, schematics not available.
Nothing after pressing power button? 3.3V on power switch?
Check resistance of R391 (0ohm), and its resistance to ground (on both sides).

nothing after power button
3.3 found on power button
resistance of R391 2.8k from both side

[mohammed aram]

Re: toshiba satellite c55-b

is this your motherboard?

no i have diffrenent board
thanks for reply

[piernov]

Re: toshiba satellite c55-b

KBC is Nuvoton NPCE985LA0DX?
Voltage on pin 102(AVCC), 115(VCC) of KBC?
Voltage on pin 95(NBSWON#), 91(DNBSWON#), 75(RSMRST#), 73(SUSC#), 94(SUSB#), 22(SUSON#) after pressing power button?

[mohammed aram]

Re: toshiba satellite c55-b

KBC is Nuvoton NPCE985LA0DX?
Voltage on pin 102(AVCC), 115(VCC) of KBC?
Voltage on pin 95(NBSWON#), 91(DNBSWON#), 75(RSMRST#), 73(SUSC#), 94(SUSB#), 22(SUSON#) after pressing power button?

pin 102 =3.3 volt
pin 115=3.3
pin95 3.3 volt go to 0 when pressing button and come back to 3.3 volt
pin 91 after pressing power button risisng 3.3 volt
pin rsmrst after pressing no response 0 volt
pin 73 have 3.3 volt and no changes after pressing
pin 94 have 0 volt and no changes after pressing
pin 22 have 0 volt and no changes

[mohammed aram]

Re: toshiba satellite c55-b

i want to know which bios chip of the kbc u u17 or u18

[piernov]

Re: toshiba satellite c55-b

Yep could be BIOS issue.
BIOS is U18 (I think). Contains both the main BIOS and the EC ROM.
Try to flash it with a known good dump (I don't have it, sorry).

[mohammed aram]

Re: toshiba satellite c55-b

Yep could be BIOS issue.
BIOS is U18 (I think). Contains both the main BIOS and the EC ROM.
Try to flash it with a known good dump (I don't have it, sorry).

i reflash the bios and not woking
the 8th leg of u 18 have no 3.3 volt before i press power button
is this normal??
any suggesion??

[piernov]

Re: toshiba satellite c55-b

What do you get on KBC pin 26(S5_ON)?

It depends on the motherboard and without schematics it is hard to tell. 3.3V for U18 may come from +3.3V_S5, which may appear only after pressing power button (if everything work correctly).

Or it may come from the always on 3.3V but you said it is present so BIOS chip should receive power if that's the case.

[mohammed aram]

Re: toshiba satellite c55-b

What do you get on KBC pin 26(S5_ON)?

It depends on the motherboard and without schematics it is hard to tell. 3.3V for U18 may come from +3.3V_S5, which may appear only after pressing power button (if everything work correctly).

Or it may come from the always on 3.3V but you said it is present so BIOS chip should receive power if that's the case.

first i would like to thank you very much for your help
second iam confused about this
i will check kbc pin 26 tomorrow but i think it will be present because the s5 voltage 5 and 3.3 present on the coils of power chip
The puzzling thing if the u18 chip is the bios chip of the kbc and the pch integrated with cpu on this platform i should find 3.3 volt on the 8th leg of u18 on s5 state to make kbc do it,s job
give me some information about this please

[piernov]

Re: toshiba satellite c55-b

Yep but laptop power rail sequences are usually very confusing, they're different from motherboards to motherboards. S5 state doesn't mean "always on" too, sometimes it is always on, sometimes it is switched from the always on rail with a MOSFET, sometimes it is created by another DC-DC converter. The two last options are usually controlled by the S5_ON signal.
Now, the BIOS chip can be powered from the always on rail, the S5 rail, the S3 rail…

Sometimes the datasheet of the KBC can help, but this one is not available.

Without schematics (and power sequence diagram), it is hard to tell. You will have to find out what the VDD pin of BIOS chip is connected to.

Maybe someone else have more information/experience on this?

[mohammed aram]

Re: toshiba satellite c55-b

KBC pin 26(S5_ON) no voltage after pressing and before pressing power button

[piernov]

Re: toshiba satellite c55-b

I guess I don't have the right pinout for the KBC then…

Could you try to find the 5V/3.3V regulator on the board? It may be an RT8223P in 24 pins QFN package with markings (? being some letter/number for datecode):
20 ??
???

And report the voltages on pin 8, 11, 13, 17, 18, 20.

Try to use your multimeter in continuity mode to check where the BIOS VDD pin is connected.

[mohammed aram]

Re: toshiba satellite c55-b

I guess I don't have the right pinout for the KBC then…

Could you try to find the 5V/3.3V regulator on the board? It may be an RT8223P in 24 pins QFN package with markings (? being some letter/number for datecode):
20 ??
???

And report the voltages on pin 8, 11, 13, 17, 18, 20.

Try to use your multimeter in continuity mode to check where the BIOS VDD pin is connected.

power chip marked with
3G=1f c16

[mohammed aram]

Re: toshiba satellite c55-b

it seemes to be RT6575A

[piernov]

Re: toshiba satellite c55-b

Ok great, in that case you get 3.3V on pin 3 and pin 8 (or 18). And you get 5V on pin 13 and pin 18 (or 8)? Do you have continuity between any of those pins and the BIOS VDD pin?

Check if the BIOS chip is 3.3V and not 1.8V too.

[mohammed aram]

Re: toshiba satellite c55-b

Ok great, in that case you get 3.3V on pin 3 and pin 8 (or 18). And you get 5V on pin 13 and pin 18 (or 8)? Do you have continuity between any of those pins and the BIOS VDD pin?

Check if the BIOS chip is 3.3V and not 1.8V too.

pin 3 =3.3 ok
pin 8 oscillate on the osclliscope
pin 13 5 volt ok
pin 18 oscillate on the osclliscope
it seems every thing is ok
bios chip is 25b64bsig and this is 3.3 volt chip not 1.8

[pete_the_geek]

Re: toshiba satellite c55-b

I have the exact same problem with a Toshiba L50B same BLI motherboard.
Both 3v3 and 5v present, also CPU heats up, no action on Power button press, no 3v3 on pin 8 SPI 25B64SIG.
Did anyone get to the bottom of this?