Pwm Modulation Check - LG OK75 Service Manual

ELECTRICAL TROUBLESHOOTING GUIDE

4. PWM MODULATION CHECK

PWM MODULATION PART
CHECK
YES
Check CN201
pin1, 2: 12 V.
YES
• Check IC601(TAS5548) 3.3 V - pin9, 14, 35, 50.
• Check X601 (12.288 MHz).
YES
Check
X601(12.288 MHz)
operation.
YES
Check IC601 pin21 CLK input.
YES
Check IC501 (MLC3730)
pin U13: RESET, pin L14: SDA
pin L13: SCL output.
YES
Check
IC601(TAS5548) input data
pin24 PWM wave.
YES
Check
PWM modulator output
FL: Pin48(-),49(+). FR: Pin46(-),47(+).
Other output
check.
YES
OK
NO
Refer to
SMPS troubleshooting.
NO
Check X601
(12.288 MHz).
OK
NO
Check line resistor output
RST: R508, SCL: R510,
SDA: R509.
OK
Check
NO
CD Assy communication
Pin22, 23, 24.
Check IC601
input data.
OK
NO
Check IC601.
OK
3-28
NO
YES
NO
YES
NO
YES
NO
YES
NO
YES
Copyright © 2018 LG Electronics Inc. All rights reserved.
Replace X601(12.288 MHz).
Replace R508, R510, R509.
Refer to
CD troubleshooting.
Check each line resistor output.
Replace IC601.
Only for training and service purposes.