LG 6870R2289AA SMPS Schematic

3-32 3-33

A B C D E F G H I J K L M N O P Q R ST

30VA No Power
D130 is Defective

No Power
BD101,TH01 is Defective

-28VA No Power
D127 is Defective

No Power
D102 is Defective

5.3VA No Power
D121 is Defective

Switching Error
IC102,IC103 are Defective

No Power
F101 is Defective

3.3V No Power
D122 is Defective

Switching Error
IC105,IC106 are Defective

S/W Error
IC107,Q111 is Defective

12V No Power
D125 is Defective

28V No Power
D129 is Defective

12V No Power
D126 is Defective

12V No Power
Q125 or ZD152 are Defective

12V No Power
IC157 is Defective

2.5V No Power
IC152 is Defective

5V No Power
IC151 is Defective

1.8V No Power
IC160 is Defective

3.3V No Power
IC154 is Defective

5V No Power
D124 is Defective

1.8V No Power
D123 is Defective

No Digitron Displayed
D128,R107,ZD151 are Defective

S/W Error
IC101,IC104 is Defective

28V No Power
Q120 or ZD153 are Defective

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.

CIRCUIT DIAGRAMS

1. POWER(SMPS) CIRCUIT DIAGRAM

IMPORTANT SAFETY NOTICE

WHEN SERVICING THIS CHASSIS, UNDER NO CIR­CUMSTANCES SHOULD THE ORIGINAL DESIGN BE
MODIFIED OR ALTERED WITHOUT PERMISSION
FROM THE ALLEGRO ELECTRONICS CORPORATION.
ALL COMPONENTS SHOULD BE REPLACED ONLY
WITH TYPES IDENTICAL TO THOSE IN THE ORIGINAL

CIRCUIT. SPECIAL COMPONENTS ARE SHADED ON
THE SCHEMATIC FOR EASY IDENTIFICATION.

THIS CIRCUIT DIAGRAM MAY OCCASIONALLY DIF­FER 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.

3-60 3-61

2. SMPS P.C.BOARD

LOCATION GUIDE