Electronics > Repair

Help about Repairing my laptop

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EbarlaS:
Hi everyone. I am trying to identify the problem of my old laptop. I upload part of aschematic of the laptop which i am thinking that is causing the error.
The schematic is showing power plane reg 3/5v.
In the schematic, circuit has 19.5v at IN pin when i check the c169 cap. And mosfet U15, U12 has power like 19.5v also but there is no voltage at gates. L15 and L13 have no voltage which must be 5v and 3.3v always.
So my question is the circuit shorted and dead that why no voltages or anything else could be possible.
And if this curcuit is the problem i will try to replace. Can u tell me codes meaning on them.
Maxim 17020 ETJ 950 + ITOZ
I found online
MAxim 17020 ETJ 848 + NTAT
So is it okay to replace with this one?

It will be great if i can get help thanks everryone who can advice me..

unknownsoldier90:
What Laptop are you trying to repair?

What about the first 2 input MOSFETs, are they fine?

I would also recommend the badcaps Forum, there are many specialists.

EbarlaS:
Hi.. my laptop dell 1750
First 2 mosfet are fine 19.5v present after that no power in the 3.3v 5v power supplies..
Thanks for the advice i can try the other forum.

unknownsoldier90:
Test the mosfets in diode mode without power.
It isn’t guaranteed that they are okay, they can be shorted.

Also measure the resistance to ground on the big coils. Possibly a faulty capacitor. If you find a rail which has low resistance try to insert voltage (1v, 1a) and see what is becoming warm.

fzabkar:
Are the two supplies being switched on? Check the ON1/ON2 pins (pin #14 = 5V enable, pin #27 = 3V enable).

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