Text preview for : Trouble shooting.pdf part of LG 775FTFB775BE-Ultra Flatron 775FTFB775BE-Ultra.part2
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TROUBLESHOOTING GUIDE
1. NO POWER
NO POWER
(POWER INDICATOR OFF)
CHECK NO TROUBLE IN FUSE
FUSE OK? (F901)
YES
CHECK
C907 VOLTAGE? NO TROUBLE IN
(AC120V: 170VDC, D900
AC220V: 310VDC)
YES
CHECK
IC901 PIN 3
WAVEFORM NO TROUBLE IN
(SQUARE WAVE IC901, IC902
COMES OUT?)
YES
CHECK
D920, D922, D924, NO TROUBLE IN
D923, D926 D920, D922, D923,
VOLTAGE? D924, D926
YES
TROUBLE IN
IC923, IC925, Q922,
Q923, Q924, Q925
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2. NO CHARACTER
NO CHARACTER
CHECK
NO TROUBLE IN
IC302 PIN 7, 15, 18,
P302 12V LINE, IC304
21(8V) ?
YES
CHECK TROUBLE IN
NO
IC302 PIN 6, 8, 10 ? PC SIGNAL,
P301 SIGNAL CABLE
YES
CHECK NO TROUBLE IN
IC302 PIN 16, 19, 22 ? IC302
YES
CHECK
NO TROUBLE IN
IC303 PIN 4 (80V)
8 (12V) ? P302 12V LINE/80V LINE
YES
CHECK
IC303 NO TROUBLE IN IC303
PIN 1, 2, 3 ?
YES
CHECK TROUBLE IN
NO R338~R341,
R, G, B CATHODE
VOLTAGE? R344, R345, L302~L304,
D307~D310, D312, D313
YES
TROUBLE IN
CRT SOCKET
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3. NO RASTER
NO VIDEO
(POWER INDICATOR ON)
CHECK
POWER INDICATOR ORANGE DPM MODE
GREEN or ORANGE? (NO H and/or V SYNC)
GREEN
CHECK NO TROUBLE IN
D712 ANODE
D712
(-130V)?
YES
CHECK TROUBLE IN
NO
G1 VOLTAGE?
Q801~Q806
( 5~25V)
YES
TROUBLE IN
D926, Q925 (6.3V)
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4. NO HORIZONTAL DEFLECTION
NO H-DEFLECTION
(ONE VERTICAL LINE)
CHECK NO TROUBLE IN
Q706? Q706
YES
CHECK NO
B+ VOLTAGE TROUBLE IN
(165V)? 165V LINE
YES
CHECK TROUBLE IN
NO
T701(FBT) PIN 7 Q717, Q718, Q719,
(40V) ? R759
YES
CHECK
NO TROUBLE IN
IC701 PIN 8
IC701
WAVEFORM?
YES
TROUBLE IN
D703, D705, D704, D706
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5. TROUBLE IN H-LINEARITY
UNBALANCED OF H-LIN.
CHECK
IC401 NO TROUBLE IN
PIN 17, 18, 19, IC401 (MICOM)
20, 21?
YES
CHECK
TROUBLE IN
Q711~Q716, NO
Q711 ~ Q716,
Q734~Q736,
Q734~Q736, Q738
Q738?
YES
Cs SIGNAL TABLE
TROUBLE IN
RL701 HORIZONTAK
FREQUENCY(fH) Cs0 Cs1 Cs2 Cs3 Cs4
66K ~ 39K H H H H H
63K ~ 66K H H L H H
57K ~ 63K H L H H H
49K ~ 57K H L L H H
46K ~ 49K L H H H H
43K ~ 46K L L H H H
36K ~ 43K L H H L H
33K ~ 36K L H H L L
30K ~ 33K L L L L L
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6. NO VERTICAL DEFLECTION
NO V-DEFLECTION
(ONE HORIZONTAL LINE)
CHECK NO TROUBLE IN
IC601 PIN 2
Q601, Q602, Q603
(15V)?
15V LINE
YES
CHECK NO TROUBLE IN
IC601 PIN 4
SMPS, D937
(-12V)?
YES
CHECK NO TROUBLE IN
IC601 PIN 1 ? IC701
YES
TROUBLE IN
IC601, V-CIRCUIT
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7. TROUBLE IN OSD
NO OSD (ENTER BUTTON MUST BE PRESSED.)
CHECK NO TROUBLE IN
IC301 B+ ? 5V LINE
DC 5V
YES
CHECK TROUBLE IN
IC301 PIN 5, 10 NO
IC601 PIN8 (V-FBP),
WAVEFORM? T701 40V LINE
Pin 10
5V
Pin 5 YES
CHECK
IC311 PIN 12 NO TROUBLE IN
WAVEFORM ? IC302, IC301
H+V
5V
YES
CHECK NO TROUBLE IN
IC311 PIN 13, 14, 15 ? IC301, IC302
H+V
5V
YES
TROUBLE IN
OSD PERIPHERAL
CIRCUIT
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8. TROUBLE IN DPM
OFF MODE FAILURE (NO OFF MODE.)
CHECK
IC401 (MICOM) CHECK PC,
INPUT H/V SYNC SIGNAL
PIN 1, 42 (H/V INPUT) (PC IS NOT GOING INTO
SIGNAL? DPM OFF MODE)
NO H/V SYNC
CHECK
IC401 PIN 6 NO TROUBLE IN
WAVEFORM? X401
5V
YES
6MHz
CHECK
NO (DPMF: 0V) TROUBLE IN
IC401 (MICOM)
IC401 (MICOM)
PIN 9, 12 ?
SEE DPM TABLE
YES
CHECK
NO
B+ LINE TROUBLE IN
(6.3V,15V) ? Q922, Q923, Q925, Q926
YES DPM TABLE
Item DPMS DPMF LED
Mode
TROUBLE IN PC NORMAL H H GREEN
STAND-BY H L ORANGE
SUSPEND H L ORANGE
OFF L L ORANGE
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9. NO DEGAUSSING
NO DEGAUSSING (DEGAUSS ON THE OSD MENU MUST BE PRESSED.)
CHECK NO TROUBLE IN
IC401 PIN 22
IC401 (MICOM)
(0V)?
YES
CHECK
NO TROUBLE IN
Q921 COLLECTOR
Q921
VOLTAGE?
DC 5V
YES
CHECK NO TROUBLE IN
P902, P903? P902, P903
YES
CHECK NO TROUBLE IN
RL901? RL901
YES
TROUBLE IN
TH902,
DEGAUSSING COIL
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10. NO TILT (NO ROTATION )
NO TILT (NO ROTATION)
CHECK
Q504 NO TROUBLE IN
WAVE FORM ? IC401 (MICOM)
YES
CHECK
15V LINE NO TROUBLE IN
AND 6.3V LINE ? 15V LINE, 6.3V LINE
YES
CHECK
Q503 EMITTER NO TROUBLE IN
VOLTAGE ? Q501~Q503
YES
TROUBLE IN
P501, TILT COIL
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