No Raster; No Picture, No Sound; Chapter 5. Trouble Shooting Flowchart - Sharp 21F-PA18 Service Manual

21Q-FG1F E Market 21Q-FG1F Service Manual TV
CHAPTER 5.
TROUBLE SHOOTING FLOWCHART
[1] TROUBLE SHOOTING FLOWCHART
CIRCUITS TO BE CHECKED:
Tuner.
PIF.
Automatic Gain Control.
(5V), (32V) Power Source.
Check the tuner supply voltage LB must
approx. 5V. BT must be approx. 33V.
And check the CH preset data.
Check pin(24) of
IC801.
Check T702 pin (17) voltage
(Approx. 310V at 220V AC)
Check NR701.
Check Secondary Main+B
(Approx. 125V)
Check D751.
Check 185V
Bias on
CRT board.

NO PICTURE, NO SOUND

Does the noise level increase at max.
Contrast, Brightness and Sound controls ?
Noise increases but no signal is
received.
Check the tuner AGC at
TP201.
Check pin (37) of
IC801, Tuner and
related circuit.

NO RASTER

Check F701.
Check CRT connector K-
wire and the signal on it.
Check
IC801.
Does horizontal circuit
oscillate ?
Check Q601 and Q602.
Does noise or signal appear at pin (24)
of IC801 ?
Does noise or
signal appear at
pin (38) and (39)
of IC801 ?
Check pin (1) of
SF201, Tuner and
related circuit.
5 – 1
21F-PD250 / 21F-PT220 / 21F-PA18 / 21F-PA18(B)
Blown out.
Replace the fuse.
The fuse is blown out again.
Check IC701, D701 and
C705.
Check Q752 for 8V regulator
circuit and Q753, IC751, Q754
for 5V regulator circuit.
Checking the
protector circuit.
No snow noise.
Check IC801 and
related circuit.
Check pin (36) at
IC801 and related
circuit.