Sharp 21HT-15 (serv.man6) Service Manual ▷ View online
32
21HT-15H
TROUBLESHOOTING TABLES.
Check F701.
Blown out.
Abnormal
Normal
Replace the fuse.
Check R701 Q701.
Check T701 pin16 voltage.
The fuse is again blown out.
and IC701
(Approx. 290V at 220V AC)
Check IC701,D701,D702,
Normal
D703,D704 and C705.
Check Secondary Main+B.
Abnormal
(Approx. 11
0V)
Normal
YES
Check D758,IC702,IC753
Check CRT connector K1-
D1001 (Power LED Bright Red)
and D762.
K5 bias.
turns on.
NO
Normal
Normal
Abnormal
NO
D1001 (Power LED Dark Red)
Check R615.
Check
Check
turns on
C878.
IC801.
Checking the
D1001 turns on
protector circuit.
brightly and darkly.
(Bus error)
NVM
(IC1002)
See many often D1001
TV PROCESSOR
flashes in red.
(IC801)
This indicates which IC to
check up.
TUNER
(TU201)
(TU201)
NO RASTER
33
21HT-15H
TROUBLESHOOTING TABLES.
NEITHER VERTICAL NOR
HORIZONTAL SYNCHRONIZATION
CIRCUIT TO BE CHECKED:
Sync. Separator Circuit.
Check pin33 and 34
of IC801.
DEFECTIVE VERTICEL AMP.
AND VERTICAL LINEARITY
Readjusted vertical size.
(Bass Data)
Vertical linearity and size
is abnormal.
Check R502,R505
NO VERTICAL SCAN
Check IC501 bias.
Normal
Abnormal
Check C502 and C514.
Check IC501.
NO SPECIFIC COLOUR
NO
YES
Is some colour produced in
B/W broadcast reception?
Check IC801,R801,R802,
YES
Is the white balance
R803,D804,D805,D806
properly adjusted?
and Q801.
NO
Readjusted the white
balance.
The picture colour is cyan.
The picture colour is magenta.
The picture colour is yellow.
Check Q870,Q885 and
Check Q871,Q883 and
Check Q872,Q887 and
their adjacent circuits.
their adjacent circuits.
their adjacent circuits.
34
21HT-15H
TROUBLESHOOTING TABLES.
NO PICTURE, NO SOUND
CIRCUITS TO BE CHECKED:
Tuner.
PIF.
PIF.
Does the noise level increase at max.
Automatic Gain Control.
Contrast,Brightness and Sound controls?
5V, 32V Power Source.
Noise increase but no
No snow noise.
signal is received.
Check the tuner supply voltage
Does noise or signal appear
LB and HB must be approx. 5V,
at pin40 of IC801?
BT must be approx. 32V,and
NO
YES
CH preset data check.
Does noise or
Check IC801
signal appear at
and its related
Normal
pin38 of IC801?
circuit.
NO
YES
Check the tuner
Does noise or
AGC at TP201.
signal appear at
Check Q401
pin23 and 24
Q402 and related
Normal
Abnormal
of IC801?
circuit.
NO
YES
Check pin38
Check pin27
Check pin1,2 of
of IC801.
of IC801,Tuner
SF201,Tuner
Check pin37 of
and related circuit.
and related
IC801 and
circuit.
related circuit.
NO SOUND
CIRCUITS TO BE CHECKED:
NO
Audio Output Circuit.
Does signal appear
Check IC801 and
at pin6 of IC303?
its related circuit.
YES
NO
Check Speaker.
Check IC303 and
peripheral circuit.
Display
