Sharp 20CT-250 서비스 매뉴얼 - 페이지 15

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Sharp 20CT-250 서비스 매뉴얼

TROUBLE SHOOTING TABLE

NO RASTER
Check F701.
Normal
Check T701 pin (1) voltage
Abnormal
(Approx. 310V at 220V AC)
Normal
Check R702 and D709.
Check Secondary Main+B
(Approx. 115V)
Abnormal
Normal
Check CRT connector K1-
Check D708 and D732.
K5 bias.
Normal
Normal
Check
Check R609 and R611.
C866 and
L851.
Horizontal circuit oscillate ?
Check Q1005, Q1006,
IC603 and IC801.
If a bus error happens, the LED RED (pin 3) indicator starts flashing and the power
is turned off. The power key is still effective.
IC1003
Fig. 1
EEPROM (ST24C04)
IC801
V/C/J (TB1226DN)
TU201
PLL (N0004KJ)
15-1
Blown out.
Replace the fuse.
The fuse is again blown out.
Check Q701 and IC751.
Normal
Check C707, D701, D702,
D703 and D704.
D1013 (Power LED Green)
turns on.
YES
NO
Abnormal
D1013 (Power LED Red)
turns on or turns ON/OFF.
ON/OFF
ON
Check
IC801
Checking the
protector circuit
Bus error
(The protector
mode.
circuit still works
See Fig. 1
even if there is no
or Check
vertical waveform
IC602.
at pin (2) of IC1001.)
YES
NO
2s
0.5s
TROUBLE SHOOTING TABLE
CIRCUITS TO BE CHECKED:
NO PICTURE, NO SOUND
» Tuner.
» PIF.
» Automatic Gain Control.
» (5V), (9V) Power Source.
Does the noise level increase at max.
Contrast, Brightness and Sound controls ?
Noise increases but no signal is
received.
Check the tuner supply voltage MB
must be approx, 9V. BP must approx.
5V. BT must be approx, 31V. And CH
preset data check.
Normal
Check the tuner AGC.
Normal
Abnormal
Check the tuner
Check IC201.
circuit.
CIRCUITS TO BE CHECKED:
NO SOUND
» SIF Amplifier Circuit.
» Sound Detector Circuit.
» Sound Switch and Att. Control.
» Audio Output Circuit.
Does noise or signal appear
at pin (13) of IC201 ?
YES
(Signal)
Does signal appear at pin
(1) and (8) of IC302 ?
YES
Does signal appear at pin
(3) of IC351 ?
YES
Check pin (5) of IC351 and
peripheral circuit.
(Continued)
No snow noise.
Does noise or signal appear at pin (21)
of IC201 ?
YES
NO
Does noise or
Check PIF circuits
signal appear at
and its related
pin (1) of IC801 ?
parts.
NO
YES
Check A/V sw
Check IC801.
circuits (IC401).
NO
Check IC201 and peripheral
circuit.
YES
(Noise)
Check pin (14), (15) of
IC201.
NO
Check Q207 and peripheral
circuit.
NO
Check IC302 and peripheral
circuit.
15-2