Main Part; Main Electrical Troubleshooting Guide; Dc-Dc Converter Circuit - LG DP351G Service Manual

MAIN ELECTRICAL TROUBLESHOOTING GUIDE

1. DC-DC CONVERTER CIRCUIT

A. NO POWER ON BY ADAPTOR
No power on
by ADAPTOR
YES
NO
Is ADAPTOR
out 12V?
YES
NO
Is D606 OK?
No +18V
NO
Is U401
3.3V OK?
YES
Replace U401
NO
Is U202 1.8V OK?
Replace U202
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Only for training and service purposes

MAIN PART

Replace ADAPTOR
Replace D606
No LCD_3.3V
No S3.3V
NO
Replace U401
NO
Replace U202
3-11
B. NO POWER ON BY BATTERY
No power on
by BATTERY
YES
NO
Is BATTERY OK?
No A+5V
No M5V
VCC_5V
Is U401
5V OK?
YES
Replace U401
Is Q402 5V OK?
Replace BATTERY
No 5VA
NO
Is U401
5V OK?
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