Sharp 21V-FS700S, Service Manual

Page: 59 / 91

21V-FS700S
5 – 1
TV 21V-FS700S Service Manual 21V-FS700S Market E
CHAPTER 5.
TROUBLE SHOOTING FLOWCHART
[1] TROUBLE SHOOTING FLOWCHART
NO RASTER
Blown out.
Replace the fuse.
Check IC701, D701 and
C705.
The fuse is blown out again.
Does horizontal circuit
oscillate ?
Check T701 pin (8) voltage
(Approx. 310V at 220V AC)
Check F701.
Check Secondary Main+B
(Approx. 125V)
Check CRT connector K-
wire and the signal on it.
Check IC1001 pin 20.
Check 185V
Bias on
CRT board.
Check
IC1001.
Checking the
protector circuit.
Check D760 for 8V regulator
circuit, IC751 for 3.3V regulator
circuit and IC752, D724, D725
for 5V regulator circuit.
Check D751,
IC702 and IC703
Check NR701.
NO PICTURE, NO SOUND
No snow noise.
Does noise or signal appear at pin (34)
of IC1001 ?
Noise increases but no signal is
received.
Check the tuner supply voltage LB must
approx. 5V. BT must be approx. 33V.
And check the CH preset data.
Check the tuner AGC at
JA402.
Check IC1001 and
related circuit.
Check pin (1) of
SF201, Tuner and
related circuit.
Check pin (40) at
IC1001 and related
circuit.
Check pin (40) of
IC1001, 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.
Does noise or
signal appear at
pin (45) and (46)
of IC1001 ?
Normal
Normal
Check Q601,
Q602 and Q803