Service Adjustment - Sharp SX68JS10 Service Manual

SX68JS10
NO. Adjustment part
1 RF-AGC
Cut-in adjustment
(Already preset.)
NO. Adjustment part
1 VIDEO DET
Level adjustment
R220
DIGITAL COMB FILTER Y LEVEL ADJUSTMENT
NO. Adjustment part
1 Digital comb filter
Y level adjust-
ment
R5406

SERVICE ADJUSTMENT

PIF CHECK ADJUSTMENT
Adjusting procedure and conditions
1 E-12CH (PAL Colour Bar) is received.
Electric field strength: 54 ± 1dBµV (75Ω Open)
2 Connect the oscilloscope to TP210 as shown
below.
0.1V
Oscilloscope
Bias Box: About 4.5V
Bias
box
Fig. 3-1
3 Lower the input electric field strength to 51 ±
1dBµV (75Ω Open).
4 Under the conditions 1 and 3, TP210 volt-
age does not vary.
Raise the input signal electric field strength to
60 ± 1dBµV (75Ω Open), and verify that it is
0.1V or more lower than TP210 of 1 and 3.
5 Set the signal at 63 to 67dBµV, and verify that
any noise is not output.
6 Set the signal at 90 to 95dBµV, and verify that
any black letter beat is not output.
VIDEO LEVEL ADJUSTMENT
Adjusting procedure and conditions
1 E-12CH B/G-PAL colour bar (100% white bar)
is received.
2 Adjust R220 to make the video output of the
AV-OUT terminal become 1.0 ± 0.05Vp-p at the
75Ω terminator.
Adjusting procedure and conditions
1 Input PAL colour bar signal (100% white colour
bar) of 1.0Vp-p at the 75Ω terminator from AV-
IN terminal.
(Input level 1.0Vp-p ± 0.05Vp-p)
2 Connect the oscilloscope to TP5400.
3 Adjust R5406 to make the Y signal (100% white)
of TP5400 become 2.0 ± 0.1Vp-p.
* Verify that all are linearly amplified. (100% white
area must not be collapsed.)
Note: If the impedance converter of
TP210
TV SET
* If there is not any problem when the
When it is adjusted at E-12ch, take
care for the voltage value.
8
Waveform and others
50/75 is not used at the electric
field strength meter of 50Ω sys-
tem, set 52 ± 1dBV for 54 ±
1dBµV (75Ω Open).
Moreover, take care for the loss
if the converter is used.
several lots of the model which em-
ploys the relevant tuner is checked,
apply the check of only 5 and 6.
Waveform and others
Waveform and others