Text preview for : Trouble shooting.pdf part of LG 775FT FB775F-EA Flatron 775FT FB775F-EA
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TROUBLESHOOTING GUIDE
1. NO POWER
NO POWER (POWER INDICATOR OFF)
CHECK FUSE OK? (F901) YES
NO
TROUBLE IN FUSE (F901)
CHECK C908 VOLTAGE? (AC120V: 160VDC, AC220V: 304VDC)
NO
TROUBLE IN D900
YES
CHECK IC901 PIN 6 WAVEFORM (SQUARE WAVE COMES OUT?)
NO
TROUBLE IN IC901
YES
CHECK D941, D942, D951, D961, D961-1, D971 VOLTAGE?
NO
TROUBLE IN D941, D942, D951, D961, D961-1, D971
YES
TROUBLE IN D908, ZD902, Q903, Q972, Q971, Q952, Q951, Q942, Q941
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2. NO CHARACTER
NO CHARACTER
CHECK IC302 PIN 9 (5V) ? YES
NO
TROUBLE IN P302 5V LINE
CHECK IC302 PIN 5, 6, 7 ?
NO
TROUBLE IN PC SIGNAL, P301 SIGNAL CABLE
YES
CHECK IC302 PIN 18, 19, 20 ?
NO
TROUBLE IN IC302
YES CHECK IC303 PIN 4 (80V) PIN 8 (12V) ?
NO
TROUBLE IN P302 12V LINE/ 80V LINE
YES
CHECK IC303 PIN 1, 2, 3 ?
NO
TROUBLE IN IC303
YES CHECK R, G, B CATHODE VOLTAGE? YES TROUBLE IN IC304 / CRT SOCKET TROUBLE IN R341~R343, R331~R333, L311~L313, D307~D315
NO
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3. NO RASTER
NO VIDEO (POWER INDICATOR ON)
CHECK POWER INDICATOR GREEN or ORANGE?
ORANGE
DPM MODE (NO H and/or V SYNC)
GREEN
CHECK D712 ANODE (-160V)?
NO
TROUBLE IN D712
YES
CHECK G1 VOLTAGE? (-45 ~ -55V)
NO
TROUBLE IN Q704
YES
CHECK CDT HEAT VOLTAGE? (6.3V)
NO
TROUBLE IN D941, Q942, Q941
YES
TROUBLE IN CDT
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4. NO HORIZONTAL DEFLECTION
NO H-DEFLECTION (ONE VERTICAL LINE)
CHECK Q706?
NO
TROUBLE IN Q706
YES
CHECK B+ VOLTAGE (49V)?
NO
TROUBLE IN 50V LINE
YES
CHECK T701(FBT) PIN 2 (31KHZ, 60V 69KHZ, 130V ?
NO
TROUBLE IN Q719, Q720, D710
YES
CHECK Q705 COLLECTOR WAVEFORM?
NO
TROUBLE IN Q705
0V T
YES
TROUBLE IN T701, P701
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5. TROUBLE IN H-LINEARITY
UNBALANCED OF H-LIN.
CHECK IC401 PIN 22, 23, 24 ?
NO
TROUBLE IN IC401 (MICOM)
YES
CHECK Q711~Q716?
NO
TROUBLE IN Q711 ~ Q716
YES
CHECK L703, Q710, D730?
NO
TROUBLE IN L703, Q710, D730
YES
Cs SIGNAL TABLE
HORIZONTAL FREQUENCY(fH)
Cs1 L L H L H L H
Cs2 L H H L L H H
Cs3 L L L H H H H
TROUBLE IN C722, C723, C726, C729
30K 34K 40K 45K 48K 56K 66K
~ ~ ~ ~ ~ ~ ~
34K 40K 45K 48K 56K 66K 70K
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6. NO VERTICAL DEFLECTION
NO V-DEFLECTION (ONE HORIZONTAL LINE)
CHECK IC601 PIN 3 (15V)?
NO
TROUBLE IN R603 15V LINE
YES
CHECK IC601 PIN 7 (40V)?
NO
TROUBLE IN HIGH-VOLTAGE OUT CIRCUIT(FBT), D721, R606
YES
CHECK IC701 PIN 12, 13?
NO
TROUBLE IN IC701
3V
YES
TROUBLE IN IC601, V-CIRCUIT
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7. TROUBLE IN OSD
NO OSD
(ENTER BUTTON MUST BE PRESSED.)
CHECK IC301 B+ ?
NO
TROUBLE IN 5V LINE
DC 5V
YES
CHECK IC301 PIN 5, 10 WAVEFORM?
Pin 10
5V
NO
TROUBLE IN IC601 PIN8 (V-FBP), T701 40V LINE (H-FBP)
Pin 5
YES
CHECK IC301 PIN 12 WAVEFORM ?
H+V 5V
NO
TROUBLE IN IC302, IC301
YES
CHECK IC301 PIN 13, 14, 15 ?
H+V 5V
NO
TROUBLE IN IC301, IC302
YES
TROUBLE IN OSD PERIPHERAL CIRCUIT
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8. TROUBLE IN DPM
OFF MODE FAILURE
(NO OFF MODE.)
CHECK IC401 (MICOM) PIN 30, 31 (H/V INPUT) SIGNAL?
NO
INPUT H/V SYNC SIGNAL
CHECK PC, (PC IS NOT GOING INTO DPM OFF MODE)
YES
H/V SYNC
CHECK IC401 PIN 13 WAVEFORM?
5V
NO
TROUBLE IN X401
6MHz
YES
CHECK IC401 (MICOM) PIN 41, 42 ? SEE DPM TABLE YES
NO
(DPMF: 0V)
TROUBLE IN IC401 (MICOM)
CHECK B+ LINE (6.3V,15V, 80V) ?
NO
TROUBLE IN Q941, Q942, Q951, Q952, Q971, Q972
YES Mode TROUBLE IN PC Item DPMF H H H L
DPM TABLE DPMS H L L L LED GREEN AMBER AMBER AMBER
NORMAL STAND-BY SUSPEND OFF
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9. NO DEGAUSSING
NO DEGAUSSING
(DEGAUSS ON THE OSD MENU MUST BE PRESSED.)
CHECK IC401 PIN 8 (0V)?
NO
TROUBLE IN IC401 (MICOM)
YES
CHECK Q953 COLLECTOR VOLTAGE? DC 15V YES
NO
TROUBLE IN Q953
CHECK P902 ?
NO
TROUBLE IN P902
YES
CHECK RL901?
NO
TROUBLE IN RL901
YES TROUBLE IN TH901, DEGAUSSING COIL
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10. NO TILT (NO ROTATION )
NO TILT (NO ROTATION)
CHECK Q504(COLLECTOR) WAVE FORM ?
NO
TROUBLE IN IC401 (MICOM)
12V
YES
CHECK 15V LINE AND 6.3V LINE ?
NO
TROUBLE IN 15V LINE, 6.3V LINE
YES
CHECK Q503 EMITTER VOLTAGE ?
NO
TROUBLE IN Q501~Q503
YES
TROUBLE IN P502, TILT COIL, D501
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