LG 6870R2289AA SMPS Schematic

CIRCUIT DIAGRAMS

1. POWER(SMPS) CIRCUIT DIAGRAM

No Digitron Displayed

D128,R107,ZD151 are Defective

No Power	-28VA No Power
BD101,TH01 is Defective	D127 is Defective

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.

			28V No Power
	No Power		Q120 or ZD153 are Defective
	D102 is Defective
	5.3VA No Power
	D121 is Defective
	30VA No Power	12V No Power		12V No Power
Switching Error	D130 is Defective	D126 is Defective		Q125 or ZD152 are Defective
IC102,IC103 are Defective		28V No Power
		D129 is Defective
		12V No Power
		IC157 is Defective
				2.5V No Power
			5V No Power	IC152 is Defective
	S/W Error	12V No Power
			IC151 is Defective
	IC107,Q111 is Defective	D125 is Defective
		5V No Power
		D124 is Defective
S/W Error	1.8V No Power
	D123 is Defective
IC101,IC104 is Defective
				1.8V No Power
				IC160 is Defective
No Power	3.3V No Power	3.3V No Power
F101 is Defective
	D122 is Defective	IC154 is Defective

Switching Error

IC105,IC106 are Defective

NOTES)			Symbol denotes AC ground.		NOTE)	Warning
					NOTE)	Parts that are shaded are critical
NOTES)		Symbol denotes DC chassis ground.			NOTE)	With respect to risk of fire or
					NOTE)	electricial shock.

NOTE :
1. Shaded(	are critical for safety. Replace only
with specified part number.
2. Voltages	DC-measured with a digital voltmeter

during Play mode.

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

P

Q

R

S

T

3-32

3-33

2. SMPS P.C.BOARD

LOCATION GUIDE

3-60

3-61