Sharp CX48K4, Service Manual

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16
16-1 16-2
CX48K4
TROUBLE SHOOTING TABLE
NO RASTER
Blown out.
Replace the fuse.
Check IC701, D701,
C707 and D710.
Abnormal
YES
NO
ON/OFF ON
NO
Abnormal Normal
The fuse is again blown out.
Does horizontal circuit
oscillate ?
Check IC751 and IC801.
D1001 (Power LED Red)
turns on or turns ON/OFF.
Check T701 pin (7) voltage
(Approx. 310V at 220V AC)
Check F701.
Normal
Check Secondary Main+B
(Approx. 115V)
Normal
Normal Abnormal
Normal
Check CRT connector
K1-K5 bias.
Check
IC801. Check
C878.
Checking the
protector circuit.
Check R615 and R618.
D1001 (Power LED Green)
turns on.
Check IC702, IC753, D758
and D762.
Check R701, R707 and
D709.
TROUBLE SHOOTING TABLE
(Continued)
NO PICTURE, NO SOUND
Does noise signal appear at
pin (44) of IC801 ?
NO SOUND
No snow noise.
Does noise or signal appear at pin (40)
of IC801 ?
Noise increases but no signal is
received.
Check the tuner supply voltage LB must
be approx. 5V, BT must be approx. 32V.
and CH preset data check.
Check the tuner AGC at
TP201.
Does noise or
signal appear at
pin (38) of IC801 ? Check IC801 and
its related circuit.
Check Q205 and
related circuit.
Check pin (1) of
SF201, Tuner and
related circuit.
Check pin (37) of
IC801 and related
circuit.
Check C356
and peripheral
circuit.
Check pin (27) of
IC801, Tuner and
related circuit.
Does the noise level increase at max.
Contrast, Brightness and Sound controls ?
CIRCUITS TO BE CHECKED:
»
Tuner.
»
PIF.
»
Automatic Gain Control.
»
(5V), (32V) Power Source.
CIRCUITS TO BE CHECKED:
»
Sound system pins (28)
and (44) of IC801.
»
Sound Detector Circuit.
»
Sound Switch and Att.
Control.
»
Audio Output Circuit.
Does signal appear at pins
(6) and (8) of IC301 ?
Check P301 or P302, IC301
and peripheral circuit.
Check Q301, pins (4) and (6)
of IC801 and peripheral
circuit.
Does signal appear at pins (28)
of IC801?
Abnormal Normal
Normal
YES
YES
YES YES
(Signal)
YES
NO
NO
NO
NO
NO
Check pin (38) of
IC801.
Check IC801.