Sharp 20U200 - TROUBLE SHOOTING TABLE; Troubleshooting Flowcharts

19
20U200, 20U250
51U200, 51U250
51U500, 51U550
19-1 19-2
TROUBLE SHOOTING TABLE
NO RASTER
Blown out.
Replace the fuse.
Check IC701, D701
and C707.
Abnormal
YES
NO
ON/OFF ON
NO
Abnormal Normal
Does horizontal circuit
oscillate ?
Check IC605, 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
Abnormal
Normal
Check CRT connector
K1-K5 bias.
Check
IC801.
Checking the
protector circuit.
Check R615 and R618.
D1001 (Power LED Green)
turns on.
Check IC702, IC753 and
D758.
Check R701, R707 and
D709.
The fuse is blown out again.
TROUBLE SHOOTING TABLE (Continued)
NO PICTURE, NO SOUND
Does signal appear at pin
(28) 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
(TP201).
Does noise or
signal appear at
pin (38) of IC801 ?
Check IC801 and
its related circuit.
Check Q203,
IC401 and related
circuit.
Check PIF circuit
and its related
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 pin (28)
of IC801.
» AV Switch Circuit.
» Surround Circuit.
» Audio Output Circuit.
Does signal appear at pins
(22) and (24) of IC401 ?
Check IC801.
AbnormalNormal
Normal
YES
YES
YES
(Signal)
YES
NO
NO
NO
Does signal appear at pins
(12) and (15) of IC303 ?
YES
NO
Does signal appear at pins
(7) and (12) of IC302 ?
YES
NO
Check headphone circuit,
P301 and their peripheral
circuit.
NO
Check pin (38) of
IC801.
Check IC401, NICAM/IGR circuit
and their peripheral circuit.
Check IC303 and its peripheral
circuit.
Check IC302 and its peripheral
circuit.
* Note: NICAM/IGR circuit for
51U500/550 only.