VAR00 LA-9201P short to ground

[bjhawfam]

Re: VAR00 LA-9201P short to ground

Okay thanks for the clarification on pu100,,, the voltages are ,,, pin 7 is 5volts and VL is also 5volts,,, the others are as stated on the schematic. I was just wondering why the capacitor gets extremely hot when the power is plugged in. Will double check the voltages on kb9012...

[bjhawfam]

Re: VAR00 LA-9201P short to ground

no 3 volts at any time

[caspian]

Re: VAR00 LA-9201P short to ground

now check which ones of the following voltages are not present after pressing the power button:
+3V_PCH, +1.5V, +3VMXM, +5VMXM, +1.8VS, +VCC_CORE, +1.5VS, +0.75VS, +3VS, +5VS, +VCCP, +VCCSA, +1.5V_CPU_VDDQ

[bjhawfam]

Re: VAR00 LA-9201P short to ground

+3V_PCH -- I found present
1.05v -- i find nothing,, just a split second voltage spike and than nothing
+3v == I found present
+5vs = not finding sizeable voltage
+1.5V_CPU_VDDQ all I find on schematic is qz13 voltage is not present at this spot illustration provided

could not locate the rest to take reading from... they show only in the PM table...

[caspian]

Re: VAR00 LA-9201P short to ground

I hope only one rail has problem.
now check all pins of QZ1 to see why +5vs is not present after turning on.

[bjhawfam]

Re: VAR00 LA-9201P short to ground

okay on qz1 I DO have the 5valw to pins 5,6,7,8 I do not get 5vs out.. Low voltage out 0.011 on 1 and lower on the 2,3 ....

[caspian]

Re: VAR00 LA-9201P short to ground

please measure pin4 of QZ1 and pin1 of PL201 and pin116 and pin115 of kb9012..

[alfasys]

Re: VAR00 LA-9201P short to ground

Hi there.
I just read Caspian posts, they are really helpful. I also have a motherboard that is short to ground. they were 2 damaged mosfets that I replaced (PQ401 and PQ402). when I plug the laptop, PQ401 get very hot (burning) and dies. I replace it 3 times, it does the same. Whe can I take the measurement and how can I proceed? Please help.

[caspian]

Re: VAR00 LA-9201P short to ground

dear alfasys
please open a new thread for the problem.

[alfasys]

Re: VAR00 LA-9201P short to ground

Thanks I will do

[bjhawfam]

Re: VAR00 LA-9201P short to ground

please measure pin4 of QZ1 and pin1 of PL201 and pin116 and pin115 of kb9012..

pin 4 of qz1 and pin 1 of pl201 inductor and pin 116 of kb9012 do essentially the same thing,,, initially they all have no power, if measured while pushing the power button there's a small amount of current/voltage and it drops or goes away... Pin 4 of qz1 only got 2volts and drops instantly,,, starts to drop voltage making it's way to 0.00...

pin 115 of kb9012 gets 3.3volts always,, without pressing the power button

[bjhawfam]

Re: VAR00 LA-9201P short to ground

the voltage on pl201 and kb9012 pin116 is negligible at best ,, very small amount when the power button is pressed.

[caspian]

Re: VAR00 LA-9201P short to ground

how much voltage on pin2 of PL401 after turning on?
measure it if exists even for a second.

[bjhawfam]

Re: VAR00 LA-9201P short to ground

there's a small amount of voltage for a second only .2 then drops....

[caspian]

Re: VAR00 LA-9201P short to ground

the culprit is not found yet.
it needs a new round of testing on other components.
if you replaced the board, avoid more tests.

[bjhawfam]

Re: VAR00 LA-9201P short to ground

It's still the same board...

[caspian]

Re: VAR00 LA-9201P short to ground

now measure pin 110 and 112 of kb9012 after power on.

[bjhawfam]

Re: VAR00 LA-9201P short to ground

both pins show 3.3v on kb9012

[caspian]

Re: VAR00 LA-9201P short to ground

now measure B+_BIAS after powering on.

[bjhawfam]

Re: VAR00 LA-9201P short to ground

OKAY was trying to measure b+ bias at pq3 how ever the schematic show pq3 as SOT23-3???? pq4 is also in the included picture??? not sure where to measure from...