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3-5
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
LGE Internal Use Only
No 5VT
Is the VCC (5.3V)
supplied to Q155 Emiter?
Check 5.3VA on SMPS Board
YES
YES
NO
Is there
about 0V at D152 and
Q152 Collector?
Check Q155 and Replace
YES
NO
Is there
about 5V at R180 and 0.7V at
Q152 Base?
Check the “TIMER H”
signal from µ-COM
YES
NO
Check Q152 and Replace
No 33VT
Is the VCC (33V)
supplied to Q161 Emiter?
Check D128 on SMPS
Board and Replace
YES
YES
NO
Is there about 0V at
Q152 Collector?
Check Q161 and Replace
YES
NO
Is there
about 5V at R180 and 0.7V at
Q152 Base?
Check the “TIMER H”
signal from µ-COM
YES
NO
Check Q152 and Replace
ELECTRICAL TROUBLESHOOTING GUIDE