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Sunday, 1 April 2018

BPL LCR 18CB 1 FAULT FINDING - 4


BPL LCR 18CB Tuning is Not Possible BPL LCR 18CB No Operation Through Remote Control While Front Panel Keyboard is Working BPL LCR 18CB No Operation Through Front Panel Keyboard While Remote Control Operation is OK BPL LCR 18CBNo Operation Through Front Panel Keyboard While Remote Control Operation is OK BPL LCR 18CB Program +- Function is Not Working BPL LCR 18CB Volume +- Function is Not Working BPL LCR 18CBBrightness Up/Dn is Not Functioning BPL LCR 18CB Colour Up/Dn is Not Functioning BPL LCR 18CB Contrast Up/Dn is Not Functioning BPL LCR 18CB No EHT, Power Supply Output is OK BPL LCR 18CB No EHT, Power Supply Output Voltage Drops BPL LCR 18CB Q432 (BU508DF) Overheats or Blows off BPL LCR 18CB Vertical Line, Sound Normal BPL LCR 18CB No Picture, No Sound, No Snow, Raster OK No Picture, No SoundBPL LCR 18CB Only Snow or Picture With Snow
Tuning is Not Possible
Key for Tuning is def., check key matrix circuit, no
output from pin no. 1 of IC701, IC701
(PCA84C444P) def, R701 (1k), C701 (82pF), R702
(5K6), C702 ( 180PF)R703(1K5), D701 (1N4148),
L701 (10uH), R741 (10K2W), C743 (4.7MF0), 33V
zener D743 (uPC574J), R704 (1219, R705 (15k),
C703 (0.1MFd), R706 (15K), C704 (0.1MFd), R707
(22K), C105 (0.47MFd), tuner defective.

No Operation Through Remote Control
While Front Panel Keyboard is Working

Check +5V supply to Remote Sensor, no output from
Remote Sensor A771 or it is faulty. R771 (220Ω)
C1 (100pF), IC 701 (PCA84C444P) defective

No Operation Through Front Panel
Keyboard While Remote Control
Operation is OK

Any key in Front Panel Keyboard is def., keypad
dusty or rusty, check KEY matrix circuit, C751-C752
(100pF), C755-C757 (100pF x 4), R751-R752 (1K
R754-R757 (1K x 4), D735-D736 (1N4148), X763
(10MHz), C763-764 (18pF), IC PCA84C444P def

Program +- Function is Not Working
Prog.+ or Prog.- key def., check key matrix circuit,
C751-C752 (100pF), C755-C757 (100pF x 4),
R751-R752 (1 K), R754-R757 (1Kx 4), D735-D736
(1N4148), X763 (10MHz), C763-C764 (18Pf),
C701 (PCA84C444P) defective

Volume +- Function is Not Working
Vol+ or Vo- key def., check key matrik circuit, no
output from pin no. 2 ofIC701, IC PCA84C444P def.,
R711 (5K6), R712 (12K), R714 (39K), C711
(3.3MFd), R145 (47K), IC101 (TDA8360) defective

Brightness Up/Dn is Not Functioning
Key for Brightness is def., check key matrix circuit,
no output from pin no. 3 of IC701, IC701
(PCA84C444P) def., R716 (33K), R717 (270K),
R719 (150K), C716 (4.7MFd), C272 (0.01MFd),
R276 (1002), IC201 (TDA8360) defective.

Colour Up/Dn is Not Functioning
Key for Colour Up/Dn is def, check key matrix
circuit, no output from pin no. 4 of IC701, IC701
PCAB4C444P) def., R721 (5K6), R722 (33K), R724
(3K9), C721 (4.7MFd), IC101 (TDA8360) defective

Contrast Up/Dn is Not Functioning
Key for Contrast Up/Dn is def., check key matrix
circuit, no output from pin no. 5 of IC701, IC701
PCA84C444P) def., R726 (47K), R727 (390K),
R729 (270K), C726 (10MFd), IC701 ITDA8360) dEf.


No EHT, Power Supply Output is OK
Check supply at collector of Q432, 0432
(BU508DF), L432, L431, R435 (10 Ω /7W), horiz.
driver trafo. T431, R434 (1K2), C434 (47MFd), C432
(1 KpF), Q431 (2SC2383), C431:0.056MFd), R432
(1K), R410 (3K3), R409 (100 Ω), check B7/8V supply
at pin no. 36 of IC101, check pin no. 36, 37, 38, 39 &
40 of IC101, IC101 (TDAB360) defective

No EHT, Power Supply Output Voltage Drops
Q432 (BU508DF) & its mica insulation, C435
(6200pF(6800pF), C436 (390pF/220pF), horiz, def,
coil, D441 (ERB43-04), C441 (150KpF/100KpF)
C442 (150KpF/180KpF), C437 (0.47MFd), EHT
transtormer T471, check diodes & capacitors related
with EHT winding or B1/130V supply line, B1/130V
supply line short.

Q432 (BU508DF) Overheats or Blows off
Abnormal supply output from power supply, check
Q432 (BU508DF) & its mica insulation, C435
(6200pF/6800pF), C436 (390pF/220pF), horiz. def
coil D441 (ERB43-04), C441 (150KpF/100KpF)
C442 (150KpF/180KpFP, C437 (0.47MFd), EHT
transformer T471, T431, over oscillation in
horizontal oscillator, check entire horizontal section
& power supply section

Vertical Line, Sound Normal
Horizontal deflection coil or its wire, D441 (ERB43-
04), L441, R441 (1K), C441 (150KpF/100KpF)
C442 (150KpF/180KpF), C437 (0.47MFd), R435
(10Ω/7W) & related components

No Picture, No Sound, No Snow, Raster OK
Q121-Q115 (2SA1015) & related components
R115 (1K), C136 (0.1MFd), check supply at pin no.
10 of IC101, T121, C129 (55pF), R124 (6K8), R123
(390 Ω), C119 (12pF), C127 (3900pF), X101, C101
(2SC2216) & related components, C128 (2.2MFd)
VR120 (10K)& related components, IC101
TDA8350), tuner defective.

No Picture, No Sound
Only Snow or Picture With Snow

Antenna & its wire, balun/adapter. RF socket, check
as given in fauit of "Band is Not Switching" & Tuning
is Not Possible", L103 (168μΗ). C101 (47MFd), tuner
def., C106 (100pF), C107 (56pF), C108 (68pF),
R101(1K2}, T101. C109 (0.01 MFd), R100 (100Ω),
C100 (0.01MFd). R102 (4K7), R103 (1K), R105
(68Ω), Q101 (25C2216), R104 (220Ω), C111
(0.01MFd), X101, T121 & related components,
C128 (2.2MFd), R127 (100Ω), VA120 (10K). R126
(5K5), C130 (o.01MFd, R133 (100 Ω), R131 (33K)
R132(47K), С131(4.7MFd), IC101 (TDA8360).
 

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