• Dell Laitude E5440 can't power on

Danes je 3 Februar 2026, 18:39

Dell Laitude E5440 can't power on

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#1 Dell Laitude E5440 can't power on

Napisal/-a cygron • 26 Februar 2023, 09:12
Model : Dell Laitude E5440
Board id : LA-9832p Rev 1.0

Laptop can't power on. I found shorted mosfet PQ51 and replace with good one. For now +3VALW and +5VALW is not comming.
Voltage to ground on PU51 pins are

Pin 12 - 17.42V
Pin 6 and 20 - 3.1V
Pin 3 - 3.3V
Pin 13 - 5V
Pin 7 - 0V
Pin 14 - 0V

Need help.

Re: Dell Laitude E5440 can't power on

Napisal/-a Google Adsense [BOT] • 26 Februar 2023, 09:12

#2 Re: Dell Laitude E5440 can't power on

Napisal/-a matic • 26 Februar 2023, 11:11
Hello!

- Measure the resistances to ground on coils PL52, PL53.
- Measure the voltages to ground on pins 9, 17 of chip PU51.

#3 Re: Dell Laitude E5440 can't power on

Napisal/-a cygron • 27 Februar 2023, 13:43
Found low resistance on PL52 (about 1 Ohm). So i remove PL52. Connect 3.3V DC Power Supply to shorted side of PL52 and found shorted IC U37 (ECE5048-LZY). When i remove U37, short is gone. So i replace U37 (ECE5048-LZY) wih good one. But when i connect adapter (DC Power Supply), this ic (U37) is shorted again.

#4 Re: Dell Laitude E5440 can't power on

Napisal/-a matic • 27 Februar 2023, 22:17
Open the jumpers PJP52, PJP53 and connect the power supply to the board. Measure the voltages to ground on coils PL52, PL53.

#5 Re: Dell Laitude E5440 can't power on

Napisal/-a cygron • 1 Marec 2023, 16:04
I also found the shorted capacitor (PC71) and replace with good one. For now, when open the jumpers PJP52 and PJP53, voltages to ground on coils are PL52 - 3.3V and PL53 - 5V. But when close the jumpers PJP52 and PJP53, voltages to ground on both coils are about 0.7V and motherboard produce some noise sound (Sheeeeee sound).
Resistance to ground on coils are
PL52, PL53 - 17K above (With open jumper)
PL52, PL53 - about 5K (With close jumper)

#6 Re: Dell Laitude E5440 can't power on

Napisal/-a matic • 1 Marec 2023, 16:13
Measure the resistances to ground on pins 8, 14 of chips U18, U43, U45, U46

#7 Re: Dell Laitude E5440 can't power on

Napisal/-a cygron • 2 Marec 2023, 09:37
U18 pin 8, 14 - about 1M
U43 pin 8 - 39 Ohm , pin 14 - 7.7K
U45 pin 8 - about 1M, pin 14 - 800K
U46 pin 8 - 20K, pin 14 - about 1M

#8 Re: Dell Laitude E5440 can't power on

Napisal/-a matic • 2 Marec 2023, 11:14
cygron napisal/-a:For now, when open the jumpers PJP52 and PJP53, voltages to ground on coils are PL52 - 3.3V and PL53 - 5V. But when close the jumpers PJP52 and PJP53, voltages to ground on both coils are about 0.7V and motherboard produce some noise sound (Sheeeeee sound).
Check what's going on in the following cases:
a) PJP52 closed, PJP53 opened
b) PJP52 opened, PJP53 closed

#9 Re: Dell Laitude E5440 can't power on

Napisal/-a cygron • 2 Marec 2023, 14:26
(a) or (b), condition are the same.

When PJP52 closed, PJP53 opened - PL53 - 0V, PL52 is about 3V and motherboard also produce some noise sound (Sheeeeee sound).
When PJP52 opened, PJP53 closed - PL52 - 0V, PL53 is about 3V and motherboard also produce some noise sound (Sheeeeee sound).

#10 Re: Dell Laitude E5440 can't power on

Napisal/-a matic • 2 Marec 2023, 16:12
Inject 3.3V from the laboratory power supply to the system side (pad 2) of jumper PJP53.
What electrical current flows from the laboratory power supply in this case?

#11 Re: Dell Laitude E5440 can't power on

Napisal/-a cygron • 3 Marec 2023, 08:40
Inject 3.3V to Jumper PJP53
With U37, it's getting hot. Without U37 power supply amps is 0.003

Inject 5V to Jumper PJP52, power supply amps is about 0.170

Re: Dell Laitude E5440 can't power on

Napisal/-a Google Adsense [BOT] • 3 Marec 2023, 09:44
 Ta tema je označena kot ARHIVSKA. Odgovorite samo, če vaše sporočilo vsebuje rešitev (Pravila in Pogoji, 12.1).
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