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CASE STUDY ACER 4739Z POWER ON AND OFF IMIDIATLY


MODEL --- ZQH

OBSERVE

LAPTOP POWER ON AND OFF IMMITIATLY AFTER 5sec

DC AMPERE LOAD WHEN POWER ON .400

THEN OFF

CHECKED FIRST ALW VOLTAGE FOUND OK 3/5 ALW

CHECKED +15V ALW OK

CHECKED S0_S5 VOLTAGE ALL OK

CHECKED THE S5_ON SIGNAL OK

CHECEKD S0 VOLTAGE AFTER POWER ON FOUND LOW

+3V = +2.1V
+5V = +3.4V

CHECKED ALL MOSFET OF S0 GATE FOUND 4 TO 5V MEANS MAIND SIGNAL LOW .. IT SHOULD BE MINIMUM 10V

THIS IS COMING FROM PQ25

THIS FAULT IS ONLY MAINON AND MAIND SIGNAL ISSUE

CHECKED AND FOUND MAINON SIGNAL IS COMING 3.3V AFTER POWER ON IN PQ26 ..BUT AGAIN BECOME ZERO

MEANS MAINON CANT CONSTANT ....IT SHOULD BE CONSTANT AFTER POWER ON FOR OK CONDITION

CHECKED AND FOUND PQ26 IS OPEN .. SO THAT MAINON DROP AFTER ON OF 5sec

REPLACE THE PQ26 AND CHECKED MAIN ON OK AFTER POWER ON 3.3V CONSTANT

THEN CHECKED MAIND SIGNAL BECOME 12V IN PQ25

AFTER REPALCE OF PQ25 ALL S0 VOLTAGE FOUND OK MEANS +3V/+5V OK

BUT STILL IN DC SUPPLY ONLY .400amp

Again checked AND FOUND +1.8V MISSING RUN VOLTAGE AT PQ60 PIN 1...2..3

CHECKED MOSFET GATE PIN4 HAVE NO VOLTAGE

THIS DRV VOLTAGE COME FROM PU12 IC PIN 5

CHECKED THIS IC FOR VCC AND EN FOUND OK BUT NO OUT PUT IN PIN 5

REPLACE THIS IC AND CHECKED PIN 5 HAVE DRV VOLTAGE

NOW RUN VOLTAGE +1.8V GENERATE IN PQ60

NOW BOARD TAKE MORE THEN 1AMP IN DC AND BOARD ALSO CONSTANT ON

DISPLAY COMING

AFTER LONG SEARCH AND LONG RESAECH



RESOULATION

ONLY CHANGE PQ26 & PU12 IC

JOB DONE SUCESSFULLY

thanks sir

Thank you

nice sir ji

[ Post made via Android ]

Thanks for sharing

good job

good job sir

can you send picture sir

VERY NICE THIS TOPIC VERY HELPFULL SAME PROBLEM IN ACER ZE6 LAPTOP ALSO