Trouble Shooting Table - Sharp 20U200 Service Manual

TROUBLE SHOOTING TABLE

NO RASTER
Check F701.
Normal
Check T701 pin (7) voltage
Abnormal
(Approx. 310V at 220V AC)
Check R701, R707 and
Normal
D709.
Check Secondary Main+B
(Approx. 115V)
Abnormal
Check IC702, IC753 and Check CRT connector
D758. K1-K5 bias.
Normal
Check R615 and R618.
Does horizontal circuit
oscillate ?
Check IC605, IC751 and
IC801.
Blown out.
Replace the fuse.
The fuse is blown out again.
Check IC701, D701
and C707.
Normal
D1001 (Power LED Green)
turns on.
YES
NO
Abnormal
D1001 (Power LED Red)
turns on or turns ON/OFF.
Check ON/OFF ON
IC801.
Checking the
protector circuit.
NO
19-1
TROUBLE SHOOTING TABLE
CIRCUITS TO BE CHECKED:
NO PICTURE, NO SOUND
» Tuner.
» PIF.
» Automatic Gain Control.
» (5V), (32V) 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 LB must
be approx. 5V, BT must be approx. 32V.
and CH preset data check.
Normal
Check the tuner AGC
(TP201).
Normal Abnormal
Check pin (27) of
Check pin (38) of
IC801, Tuner and
IC801.
related circuit.
CIRCUITS TO BE CHECKED:
NO SOUND
» Sound system pin (28)
of IC801.
» AV Switch Circuit.
» Surround Circuit.
Does signal appear at pin
» Audio Output Circuit.
(28) of IC801 ?
Does signal appear at pins
(22) and (24) of IC401 ?
Does signal appear at pins
(12) and (15) of IC303 ?
Does signal appear at pins
(7) and (12) of IC302 ?
Check headphone circuit,
P301 and their peripheral
circuit.
(Continued)
No snow noise.
Does noise or signal appear at pin (40)
of IC801 ?
NO
Does noise or
Check IC801 and
signal appear at
its related circuit.
pin (38) of IC801 ?
NO YES
Check PIF circuit
Check Q203,
and its related
IC401 and related
circuit.
circuit.
NO
Check IC801.
YES
(Signal)
Check IC401, NICAM/IGR circuit
NO
and their peripheral circuit.
* Note: NICAM/IGR circuit for
YES
51U500/550 only.
NO
Check IC303 and its peripheral
circuit.
YES
NO
Check IC302 and its peripheral
circuit.
YES
19-2
YES