LG 795FT, FB795BE TROUBLESHOOTING GUIDE

TROUBLESHOOTING GUIDE

- 18 -

NO POWER

(POWER INDICATOR OFF)

TROUBLE IN
D901

TROUBLE IN
FUSE (F901)

TROUBLE IN
IC901 or Q902

TROUBLE IN
D921, D922, D931,
D924, D925, D926

TROUBLE IN
IC903

CHECK

FUSE OK?

CHECK

C912 (+) VOLTAGE?

(250VDC)

NO

YES

YES

YES

YES

NO

NO

NO

CHECK

Q902 DRAIN

WAVEFORM (SQUARE

WAVE COMES OUT?)

CHECK

D921, D922, D931,

D924, D925, D926

VOLTAGE?

1. NO POWER

- 19 -

2. NO CHARACTER

CHECK

IC302 PIN 3, 8,12 (12V),

PIN 17 (5V)?

CHECK

IC302 PIN 2, 6,11 ?

CHECK

IC302 PIN 29, 32, 35 ?

CHECK

IC303 PIN 2, 8, 12 ?

TROUBLE IN
P302,
5V, 12V LINE

TROUBLE IN
PC VIDEO CARD,
SIGNAL CABLE

TROUBLE IN

IC302

TROUBLE IN
Q330, Q331, Q332

TROUBLE IN
CRT SOCKET

NO

YES

NO

NO

NO

YES

YES

CHECK

R, G, B CATHODE

VOLTAGE?

TROUBLE IN

IC303

NO

YES

YES

NO CHARACTER

- 20 -

3. NO RASTER

NO VIDEO

(POWER INDICATOR

GREEN or ORANGE)

CHECK

POWER INDICATOR

GREEN or ORANGE ?

CHECK

SCREEN CONTROL

VOLUME OF FBT

CHECK

VOLTAGE AT

D926 CATHODE (198V)

D924 CATHODE (78V)

IC911 OUT (12V)
D932 CATHODE

(7.5V)?

CHECK

IC202 (MICOM) PIN 5

(5V, HIGH), IC701 PIN 16

12V (HIGH)?

ROTATE SCREEN
CONTROL VOLUME TO
CLOCKWISE

TROUBLE IN
IC202 (MICOM),
IC701 (T/BASE), UPC1884ACT

TROUBLE IN
SECONDARY CIRCUIT
OF T901, T902

TROUBLE IN PRIMARY
CIRCUIT OF T901, T902

TROUBLE IN
P302 SIGNAL CABLE

ORANGE

MIN.
(Counter-clockwise)

GREEN

OK

YES

NO

YES

NO