Comb Filter Operation Check; Audio Operation Check; Tone Control Operation Check; Perfect Volume Operation Check - Hitachi 53SDX20BB 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 PERFECT PICTURE to OFF.
Adjustment procedure
(1) Check that between the color bars there are line dots
every second color bar as shown in the drawing.
A
Check A and
B
LINE
A
B

1.3 AUDIO OPERATION CHECK

1.3.1 TONE CONTROL OPERATION CHECK

Adjustment preparation
(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
suppressed when adjusted to max. or min. of the
adjustment mode.
(2) Select TREBLE mode and check that the audio
ouput 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 adjusted to right or
left of the adjustment mode.
1.3.2 PERFECT VOL. OPERATION CHECK
Adjustment preparation
(1) Set PERFECT VOL. mode to on.
(2) Set the Volume to around the center.
(3) Set to SURROUND OFF.
(4) Set INTERNAL SPEAKER to ON.
Adjustment procedure
(1) Input 100mVrms, 200mVrms, 300mVrms and
400mVrms of 1KHz audio signal to L/Mono terminal.
(2) Check that same level sound is ouput from SP when
200mVrms, 300mVrms and 400mVrms of 1KHz
sound signal is input.
A A
B
line dots.
DOT
X
X

1.3.3 SRS SURROUND OPERATION CHECK

Adjustment preparation
(1) Set the Master Volume to around the center. (Vol.30)
(2) Set the BALANCE to the center.
(3) Set the BASS and TREBLE to the center.
(4) Set LOUDNESS to OFF.
(5) Set PERFECT VOLUME to OFF.
(6) Set INTERNAL SP to ON.
(7) Set BBE to OFF.
(8) Input the audio signal of 400Hz in order with level of
1Vpp to the R audio input and no signal to the L
audio input.
Adjustment procedure
Check the following waveform at the HiFi out.
Output
HiFi L out
HiFi R out

1.3.4 BBE SURROUND OPERATION CHECK

Adjustment preparation
(1) Set the Master Volume to around the center. (Vol.30)
(2) Set the BALANCE to the center.
(3) Set the BASS and TREBLE to the center.
(4) Set LOUDNESS to OFF.
(5) Set PERFECT VOLUME to OFF.
(6) Set INTERNAL SP to ON.
(7) Set SRS to OFF.
(8) Input the audio signal of 100Hz in order with level of
1Vpp to the R audio input and 10kHz in order with
level of 1Vpp to the L audio input.
Adjustment procedure
Check the following waveform at the HiFi out.
Output
HiFi L out
HiFi R out
22
SRS
ON OFF
4.2±0.5Vpp No signal
5.0±0.5Vpp 1.8±0.5Vpp
BBE
ON OFF
0.4±0.05Vpp 0.2±0.05Vpp
0.4±0.05Vpp 0.2±0.05Vpp