Trouble Shooting Table - Sharp 21C-FX1C Service Manual

TROUBLE SHOOTING TABLE

NO RASTER
Check F701.
Check T701 pin (7) voltage
(Approx. 310V at 220V AC)
Check R701, R707 and
D709.
Check Secondary Main+B
(Approx. 120V)
Check D758, IC702, IC753 Check CRT connector K1-
and D762. K5 bias.
Check
Check R615.
C878.
Does horizontal circuit
oscillate ?
D1001 (Power LED red)
turns on and off.
(Bus error)
Check IC605, IC751 and
IC801.
EEP ROM
(IC1003)
TV PROCESSORE
See many often D1001
(IC801)
flashes in red.
This indicates which IC to AV SWITCH
(IC401)
check up.
SOUND PRPCESSOR
(IC305)
(NICAM/IGR) DECODER
(IC2300)
TUNER
(TU201)
Blown out.
Replace the fuse.
The fuse is again blown out.
Check IC701, D701 and
C707.
D1001 (Power LED Green)
turns on.
D1001 (Power LED Red)
turns on or turns ON/OFF.
Check
IC801.
Checking the
protector circuit.
LIGHTS UP
TURN OFF
26-1
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 and
HB must be approx. 5V. BT must be
approx. 32V. and CH preset data check.
Check the tuner AGC at
TP201.
Check pin (27) of
Check pin(38) of
IC801, Tuner and
IC801.
related circuit.
CIRCUITS TO BE CHECKED:
» Sound Detector Circuit.
» Sound Switch and Att.
Control.
» Audio Output Circuit.
Does noise signal appear at
pins (3) and (22) of IC305 ?
Does signal appear at pins
(2) and (5) of IC302 ?
Check Speaker.
(Continued)
No snow noise.
Does noise or signal appear at pin (40)
of IC801 ?
Does noise or Check IC801 and
signal appear at its related circuit.
pin (38) of IC801 ?
Does noise or
signal appear at
Check IC401 and
pin (23) and (24)
related circuit.
of IC801 ?
Check pin (1) of
Check pin (37)of
SF201, Tuner and
IC801 and related
related circuit.
circuit.
NO SOUND
Check TV sound.
Is there audio signal at pins (3)
and (5) of SC2300?
(NICAM/IGR unit socket)
Check NICAM/
Check IC401.
Check IC302 and
IGR unit, tuner
peripheral circuit.
and its peripheral
circuit.
*NOTE:
NICAM/IGR for model
21C-FX5/8 .
26-2