LG RH1777, Service Manual

Page: 42 / 110

3-43 3-44
CIRCUIT DIAGRAMS
1. SMPS 1 CIRCUIT DIAGRAM
No Power
BD101, TH101 is Defective
S/W Error
IC101 is Defective
No Power
D102 is Defective
No Power
F101 is Defective
Switching Error
IC102,IC103 are Defective
33VA No Power
D125 is Defective
5V No Power
IC156, IC155 are Defective
5.3VA No Power
D128 is Defective
3.8VA No Power
D127 is Defective
13.5VA No Power
D124 is Defective
5V No Power
D125 is Defective
-28VA No Power
D122 is Defective
FD(+)FD(-) No Power
D121 is Defective
A
1
2
3
4
5
6
7
8
9
10
11
12
B C D E F G H I J K L M N O P Q R S T
NOTES) Symbol denotes AC ground.
NOTES) Symbol denotes DC chassis ground.
NOTE) Warning
NOTE) Parts that are shaded are critical
NOTE) With respect to risk of fire or
NOTE) electricial shock.
(W, NTSC)
IMPORTANT SAFETY NOTICE
WHEN SERVICING THIS CHASSIS, UNDER NO CIR-
CUMSTANCES SHOULD THE ORIGINAL DESIGN BE
MODIFIED OR ALTERED WITHOUT PERMISSION
FROM THE LG ELECTRONICS CORPORATION. ALL
COMPONENTS SHOULD BE REPLACED ONLY WITH
TYPES IDENTICAL TO THOSE IN THE ORIGINAL CIR-
CUIT. SPECIAL COMPONENTS ARE SHADED ON THE
SCHEMATIC FOR EASY IDENTIFICATION.
THIS CIRCUIT DIAGRAM MAY OCCASIONALLY DIF-
FER FROM THE ACTUAL CIRCUIT USED. THIS WAY,
IMPLEMENTATION OF THE LATEST SAFETY AND
PERFORMANCE IMPROVEMENT CHANGES INTO
THE SET IS NOT DELAYED UNTIL THE NEW SERVICE
LITERATURE IS PRINTED.
NOTE :
1. Shaded( ) parts are critical for safety. Replace only
with specified part number.
2. Voltages are DC-measured with a digital voltmeter
during Play mode.