LG 577LM, LM577B TROUBLESHOOTING GUIDE

TROUBLESHOOTING GUIDE

- 17 -

1. NO POWER

CHECK U22, U11.

CHECK

U22 PIN5 VOLTAGE

(5V) ?

NO

NO POWER

(POWER INDICATOR OFF)

CHECK ADAPTER,

AND FIND OUT

A SHORT POINT

AS OPENING

EACH POWER LINE

CHECK J1’S

VOLTAGE

(24V) ?

NO

CHECK T1’S PRIMARY

COIL (OPEN CHECK)

CHECK

U17 Voltage

(5V) ?

NO

U13’S PIN11

0V ?

CHECK U13, AND
CHECK 5VA LINE

CHECK IIC LINE

CONNECTION

(U3, U1)

CHECK U4’S VCC,

XTAL, RESET

IS U5 PIN12

VOLTAGE REPEATED

AS PULSE SHAPE ?

NO

YES

YES

YES

NO

YES

NO PROBLEM

NO

CHECK KEY CONTROL

CONNECTOR ROUTINE

- 18 -

2. NO RASTER (OSD IS NOT DISPLAYED) – INVERTER

CHECK MICOM INV

ON/OFF PORT.

J4 PIN5

5V?

NO

NO RASTER

(OSD IS NOT DISPLAYED)

CHECK ADAPTER

J4 PIN10

24V?

NO

1. CONFIRM BRIGHTNESS
OSD CONTRL STATE.

2. CHECK MICOM DIM-ADJ
PORT

J4 PIN1

5V?

NO

REPLACE

INVERTER ASS’Y

CHECK

PULSE AS

CONTACTING SCOPE

PROBE TO CAUTION LABEL.

(CONTACT PROBE TO

CAUTION LABEL.

CAN YOU SEE PULSE

AT YOUR

SCOPE?

NO

REPLACE CCFL LAMP

IN THE LCD MODULE

YES

YES

YES

YES