ViewSonic N2652w-1M Service Manual page 34

1.5. TV receiving test:
1.5.1 TV SIGNAL TEST ITEM
CENTRALISM TRANSMITTING SIGNAL CHECK CONTENT
FREQUENCY
CHANNEL
ORDER
CHANNEL 2
CHANNEL 6
CHANNEL 7
CHANNEL 13
CHANNEL 14
CHANNEL 36
CHANNEL 69
TV TEST METHOD
A.CHANNEL2 Examines sound by ear, whether the sound does have mechanical resonation and
the electrical unusual sound, and image to sound disturbance.
B.CHANNEL6: Check sound and picture.
C.CHANNEL7: Examines whether the sound does receive the image disturbance, Judgment basis:
Whether there is unusual sound, input signal LEVEL<=36dBu,and STEREO SENSITIVITY is
normal.
D.CHANNEL13: Under main/sub/main-sub mode, check sub function.
E.CHANNEL14: Examines whether the sound does receive the image disturbance, Judgment basis:
Whether there is unusual sound.
F. CHANNEL 36:Check T1 of close-caption. Input signal level<=45dBu.
G.CHANNEL 69: Adjustment attenuator, If the critical point of the change of the image signal to
noise ratio is under LEVEL<=60dBu, regards as normally.
PRODUCTS OUTPUT CHECK ITEM.
A. The same as " CENTRALISM TRANSMITTING SIGNAL CHECK CONTENT"
B. saturation TEST, inputs the TV signal, the input signal LEVEL establishment most greatly is
90dBu,check whether CONTRAST of the image is normal; Whether appears the disturbance
phenomenon.
C.AFT CHECK,
(1) The frequency of the input TV signal is 211.25MHz (CH13), after confirmed the TV set
receives this signal, closure radio station; Then set frequency of the TV signal generator to be
212.25MHz, turn on the TV set and check whether the TV set receives the signal of CH13.
(2). The frequency of the input TV signal is 211.25MHz (CH13), after confirmed the TV set
receives this signal, closure radio station; Then set frequency of the TV signal generator to be
212.00MHz, turn on the TV set and check whether the TV set receives the signal of CH13.
(3). After all of FUNCTION TEST completed, we must erase all saved changes again and
restore the factory defaults.
1.6. DTV TEST ITEM
FREQUENCY
CHANNEL
471.25MHz
14
603.25MHz
36
801.25MHz
69
DTV CHECK METHOD
.
A CHANNEL14: Check whether there are some pause or the mosaic phenomenon in the picture.
B.CHANNEL36: Check whether the color of the color bar is normal.
C.CHANNEL69: Turn RF attenuator and check the critical point of the change of the image's
S/N is under LEVEL<45~85> dBu, regards as normally.
TIMING TABLE (FACTORY PRESET MODE)
ViewSonic Corporation
(MHz)
PATTERN
55.25 MONO SCOPE
83.25 COLOR BAR
175.25 Full White (100
IRE)
211.25 STAIR
471.25 MULTIBURST
603.25 MULTIBURST
801.25 MONO SCOPE
SOUND
Y
Y
Y
SET CONTENT
SOUND P/S(dB)
SWEEP TONE -10
400Hz -10
STEREO -10
DUAL -10
MONO -16
MONO -10
MONO -10
(1KHz)
dB PETTEN
50 Dynamic picture
50 Color bar
75 Dynamic picture
(TABLE 3)
31
Confidential - Do Not Copy
CHECK
CONTENT
ELECTRIC
ABNORMITY SOUND
SOUND ,PICTURE
STERO FUNCTION
SUB FUNCTION
IMAGE AND SOUND
DISTURB
TEST Close-caption T1
FUNCTION
NOISE LIMMITTED
SENSITIVITY
CHECK CONTENT
Picture
Color
Sound and Picture
N2652w-1M