ACER ASPIRE 5517 burnt MOSFET

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

Check resistance of all capacitors on U22. Note if any of them reads less than 3ohm.
Check resistance relative to ground on pins 5 to 8 of PQ8.
Check voltage on gates of PQ7 and PQ8

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

Check resistance of all capacitors on U22. Note if any of them reads less than 3ohm.
Check resistance relative to ground on pins 5 to 8 of PQ8.
Check voltage on gates of PQ7 and PQ8

The capacitor on u22 u mean the ones on top of the chip?

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

Yes

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

Yes

dont i need an ESR meter to check the resistance of a capacitor?

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

No, you are not checking the resistance of the caps but the resistance at the caps. Check both sides of each cap relative to ground (one side is the ground).

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

No, you are not checking the resistance of the caps but the resistance at the caps. Check both sides of each cap relative to ground (one side is the ground).

I found two cap that measure lower than 3Ω

you can see in the photo i attach which ones

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

That's not good. Hope your Northbridge is not shorted. You have to find which line is shorted. Check resistance relative to ground on PJ1, PJ2, PJ3, PJ4, PJ5, PJ6, PJ7, PJ8, PJ21, PJ10.
Report the results.

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

That's not good. Hope your Northbridge is not shorted. You have to find which line is shorted. Check resistance relative to ground on PJ1, PJ2, PJ3, PJ4, PJ5, PJ6, PJ7, PJ8, PJ21, PJ10.
Report the results.

PJ1----- 26KΩ
PJ2----- 1.64KΩ
PJ3----- 36KΩ
PJ4----- 9ΜΩ and was keep decreasing
PJ5----- 24.3MΩ
PJ6 ----- 334Ω
PJ7----- 322Ω
PJ8 ----- 159Ω
PJ21----- 11Ω
PJ10----- 2ΜΩ and was keep decreasing

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

Check resistance of capacitors under the northbridge (other side of board) to find which line is shorted.

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

Check resistance of capacitors under the northbridge (other side of board) to find which line is shorted.

i found 4 caps with low resistance around 10-12 Ω

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

These are on the NB_CORE line which gives you 11Ω resistance. We are looking for less than 3Ω like the ones you have on the chipset.

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

These are on the NB_CORE line which gives you 11Ω resistance. We are looking for less than 3Ω like the ones you have on the chipset.

i ve check and recheck but could find any low resistance on the caps.

what else should i check any ideas?

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

Does removing the northbridge would help me in anyway

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

The only voltages I can see of Northbridge that you didn't check are 1.8vs and 1.2V_HT. Check resistance on pins 1 to 3 of U37 and U46.
Are you certain that both sides of the caps on north you mention read less that 3Ohm?
What is the resistance and voltage on pin 4 of PQ7 and PQ8?

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

The only voltages I can see of Northbridge that you didn't check are 1.8vs and 1.2V_HT. Check resistance on pins 1 to 3 of U37 and U46.
Are you certain that both sides of the caps on north you mention read less that 3Ohm?
What is the resistance and voltage on pin 4 of PQ7 and PQ8?

U37 Resistance 6.6 kohms
U46 Resistance 232 ohms

I check them again. zero resistance on both sides

PQ7 Resistance 770 kohms voltage 13.2 V
PQ8 Resistance 3.7 Mohms Voltage 13.2 V

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

You mentioned on a previous post that there is no voltage on the drain pins of PQ8.
What is the resistance on those pins?

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

2 MOhms and decreasing

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

Check and if faulty replace PQ7 and PQ8

[nearxos]

Re: ACER ASPIRE 5517 burnt MOSFET

Check and if faulty replace PQ7 and PQ8

how do i check if there faulty?

[atsio]

Re: ACER ASPIRE 5517 burnt MOSFET

https://www.youtube.com/watch?v=RBJGOOTEwfU