Toshiba P850 / LA-8391 Boardview required, no POST

[inflex]

Have a Toshiba P850 / LA8391P board machine. Lights come on, responds to power button, but no backlight, no POST, no beeps, no activity on USB ports either, "on" state remains on until forced off.

Looking for the Boardview for this mainboard, already have the schematic.

Thanks.

[inflex]

Re: Toshiba P850 / LA-8391 Boardview required, no POST

I seem to have the luck when it comes to getting boards to repair that have either no schem, or no boardview

[highpulse]

Re: Toshiba P850 / LA-8391 Boardview required, no POST

first of all , wich is the AMP consume when it does turn on ?

also chek for PLTRST signal from KBC or PCH !

let me know , for i can e«help you out!

does it charge battery well ?

[inflex]

Re: Toshiba P850 / LA-8391 Boardview required, no POST

Hello Highpulse, I don't have the current consumption as yet.

0.0V on +GFX_CORE

CPU is warm. Fan is spinning/stopping to manage the thermal.

PLT_RST# is 3.38V ( measured on Pin 23 of UW1 / RTS5229 )

Battery is detected when plugged in - unsure if it's actually charging.

[inflex]

Re: Toshiba P850 / LA-8391 Boardview required, no POST

UPDATE:

Checking on the generation of +CPU_CORE and +GFX_CORE;

I have ~300kHz PWM for +CPU_CORE and getting ~1.1V

I have 0Hz for +GFX_CORE
PU502's ENABLE pin is high, I have 5V on VCC, but I have no PWM_IN on Pin#2 and there's no PWM output on pin #45 of the NCP6132AMNR2G QFN PU500 (diode test shows 0.7V, so doesn't appear to be shorted, but it has a DC value of ~1.9V)

I removed R546 (pull down on the PWM line) and the resistance was still about 14K which isn't what I was expecting. The NCP5911 driver I would have expected should be high impedance input.

According to the spec sheet for the NCP5911, 1.9V is considered a mid-state.... so perhaps the problem is further up stream and the NCP6132 isn't trying to generate the PWM ?

[inflex]

Re: Toshiba P850 / LA-8391 Boardview required, no POST

bump

[inflex]

Re: Toshiba P850 / LA-8391 Boardview required, no POST

Having another shot at the board today - lazy hot Summer.

I've noticed that in spite of PWR_ON_LED# going low as it should when the power button is pressed, SUSP# doesn't go high.

LID_SW# is high.

I don't seem to have CPU_CORE any more which is to be expected I suppose given that SUSP# is low (I've checked the output of SUSP# and it's not shorted to ground, only thing I get is it going from 0V -> 0.0014V when I press the power button ).

+5VALW is present.

Any other signals that can keep the system in a suspend state, or rather prevent it coming out of it? Still seems odd that the PWR_ON_LED# illuminates, makes me wonder if there's an issue with the SUSP# pin itself in the KB9012QF-A3_LQFP128 chip.

EDIT: Updates:

PCH_RSMRST# goes high when power button pressed (3V3)
POK is high (5V)
ACIN is high
PCH_ACIN / +3VALW_PCH goes high when button pressed.

PM_SLP_S5# never goes high that I can see, no apparent short to ground. UB2 has power (3.3V)

[highpulse]

Re: Toshiba P850 / LA-8391 Boardview required, no POST

hi inflex , chek NCP6132A they are common to malfunction , usually replacing , will give you again DRVEN , thqat will wake up the little NCP for GFXCORE , pin 2 usually must be 2 volts , pin1 bst is 5 volts , pin 3 should be enable 4.8 to 5 volts also chek that if SW is not been sent , chek well mosfet for gfxcore , if they are ok , replace NCP for gfxcore