Comb Filter Operation Check; Audio Operation Check; Tone Control Check; Constant Volume Operation Check - Sharp 50NP4 Service Manual

1.2 Comb filter operation check

Adjustment preparation
(1) Receive the color bar signal at the regular
tuning point.
(2) Set the CONTRAST control to MAX and the
other controls to center.
(3) Set the O.P.C. to OFF.
Adjustment procedure
(1) Check that between the color bars there are not
line dots every second color bar as shown in the
drawing.
A A
Check A and line dots.
B
A
B

1.3 AUDIO OPERATION CHECK

1.3.1 TONE CONTROL CHECK

Preparation for adjustment
(1) Input an audio signal of 250Hz and 3Khz in
order with level of 150mVrms to the L/mono
audio input.
(2) Set the Volume to around the center.
(3) Set SRS SURROUND to OFF.
(4) Set LOUDNESS to OFF.
(5) Set INTERNAL SPEAKER to ON.
Adjustment Procedure
(1) Select BASS mode and check that the audio
output level of the speakers changes to
emphasized or supporessed when adjust to
max. or min. of the adjustment mode.
(2) Select TREBLE mode and check that the
audio output level of the speakers changes
by emphasized or suppressed when adjust to
max. or min. of the adjustment mode.
(3) Select BALANCE mode and check that the
audio output changes right or left when adjust
to right or left of the adjustment mode.
A
B
SP05
No Dots
No Dots

1.3.2 CONSTANT VOLUME OPERATION CHECK

Preparation for adjustment
CONSTANT VOLUME mode should be ON.
Procedure
(1) Input 100mVrms, 200mVrms, 300mVrms and
400mVrms of 1KHz sound signal to L/MONO
terminal.
(2) Check same level sound is output from SP
when 200mVrms, 300mVrms and 400mVrms
of 1KHz sound signal is input.

1.3.3 SRS CHECK

Preparation for adjustment
(1) Set the AUDIO SETTINGS as follows:
BALANCE:CENTER BASS and
TREBLE:CENTER, INTERNAL
SPEAKER:ON, LOUDNESS:OFF,
CONSTANT VOL:OFF.
(2) Input the signal to the VIDEO INPUT (R)
terminal as follows.
R ch: 400Hz 1Vpp
L ch: no signal
Adjustment procedure
(1) Check that the following waveform is output
at HiFi output (L).
(a) SRS : OFF
(b) SRS : ON
(2) Check that the following waveform is output
at HiFi (R) output.
(a) SRS : OFF
(a) SRS : ON
35
1Vpp
0
1.4Vpp ±0.05
0
0 1.9Vpp ±0.05
0 0.3Vpp ±0.05