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problem--- no power on dead

LAPTOP --- C700

BOARD PART -- LA-4031P

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first look before dignosis
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at dc jack light glow when put adapter

means step down section aproxly ok alw voltage ok

suspected first look bios issue

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dignosis
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checked the board found 3.3v & 5v ok

checked in power switch also 3.3v ok

when press power switch no diflect in load amp that is .20amp

checked the bios chip in pin 8 have always 3.3v ok

checked the bios chip pin no 1 have no voltage means bios corrupt or SIO issue

checked once again after brush the bios with ok bin also have no voltage in bios chip pin 1

bios chip pin 1 conected to sio pin no 128 via one resister R345 (0 OHMS)

checked that resister track cuted so joint that track with resister also same issue no volt in bios pin1

bios pin 1 is FSEL# SIGNAL which is genetare from sio by through pin128

at this time once saw SIO crystal aslo damaged

changed the sio Crytal 32.7 and checked also no voltage in pin 1 of bios

checked the NBSWON SIGNAL ALSO OK 3.3V also acin/acok voltage is also ok 3.3v

checked the onoffbtn# voltage also ok 3.3v

checked the EC_ON on sio pin 102 is missing

EC_ON is generated through SIO IC

SO suspected sio issue


resolution
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change the sio ENE KB926QF B1 WITH NEW ONE AND CHECKED THE EC_ON ON PIN 102 OF SIO OK

ALSO 3V OK IN PIN 1 IN BIOS CHIP AS FSEL# SIGNAL

NOW PRESS THE POWER BTN AND BOOM

LAPTOP POWER ON AND DISPLAY OK

great

[ Post made via Android ]

Thanks..

great ha ha ha

nice one sir

great sir g

very good thankyou

[ Post made via Linux Laptop ]