LG RH178H Service Manual page 18

No SW_12VG
YES
NO
Is the VCC (14V) sup-
plied to Q165 Collector?
YES
NO
Is there about 12.5V at
ZD152 & Q165 Base?
YES
NO
Is the VCC (33V) sup-
plied to Q160 Emitor?
YES
NO
Is there about 0V at
Q160 Base?
YES
NO
Is there about 5.3V
at Q166 Base?
YES
Check Q166 and
Replace
No 1.8V
YES
NO
Is the VCC (3.3V) supplied to Q159
Emitor And IC154 pin 1,2,8 ?
YES
NO
Is there about 3V ~ 3.3V at
Q159 Base and IC154 pin 3 ?
YES
Check IC154 and
Replace
Check D124 on SMPS
Board and Replace
Check Q165 and
Replace
Check D126 on SMPS
Board and Replace
Check Q160 and
Replace
Check SW_5.3VA
Check 3.3V power
supply
Check Q159 and
Replace
No SW_FD(+)
YES
Is the VCC (FD+) sup-
plied to Q163 Collector ?
YES
Is there about 5.3V at R184
and Q153 Collector ?
YES
Is the VCC (5.3V) sup-
plied to Q153 Emitor ?
YES
Is there about 0V
at Q153 Base ?
YES
Check Q153 and
Replace
No 1.25V
YES
Is the VCC (2V) supplied
to Q154 Emitor ?
YES
Is there about 2V ~ 2.5V at
Q154 Base and IC154 pin 4?
YES
Is the VCC (3.3V) sup-
plied IC154 pin 1,2,8 ?
YES
Check IC154 and
Replace
3-6
NO
Check D121 on SMPS
Board and Replace
NO
Check Q163 and
Replace
NO
Check 5.3VA on
SMPS Board
NO
Check the 'STANBY
H' signal from µ-COM
NO
Check D155 and
2.5V power supply
NO
Check Q159 and
Replace
NO
Check 3.3V power
supply