JVC GY-HD100E, Руководство по обслуживанию

Страница: 76 / 78

3-19
Measuring Measuring point (
*
)
No. Item instruments & Mode Adjustment parts (
-
) Adjustment procedure
Input signals Adjustment level (
+
)
2 ME SP VCO
[Error rate
adjustment] • Self-REC/
PLAY
• ADJUST
MENU
No.102
*
TP2 (SBE)
[REWRITE BOARD]
-
JOG dial
+
Minimum error rate,
which should be = 498
or less (per CH)
Note:
• Be sure to use a brand-new tape for this ad-
justment.
• Be sure to clean the drum with a head clean-
ing tape before adjustment.
• The error rate should be mesured with the
Viterbi OFF. The Viterbi is set to OFF auto-
matically when the adjustment mode is en-
tered.
(1) Prior to the procedure below, prepare self-
recording tape.
(2) Select "102. ME SP VCO" adjustment.
(3) Play back the self recording tape, and decrease
the VR DATA to make the SBE waveform ab-
normal. (Fig. 3.5.2(2)) (Pressing the [STATUS]
button simultaneously with the JOG dial var-
ies the adjustment value by ±10 steps)
(4) Increase the adjustment VR DATA little by lit-
tle, and define the point where the SBE wave-
form becomes normal as value "A". (Fig.
3.5.2(3))
(5) Increase the adjustment VR DATA to make
the SBE waveform abnormal. (Fig. 3.5.2(2))
(6) Decrease the adjustment VR DATA little by lit-
tle, and define the point where the SBE wave-
form becomes normal as "B". (Fig. 3.5.2(3))
(7) Calculate the intermediate value "C" between
the point A and the point B, and set the value
C. (Since the adjustment values are hex
number, use a functional computation-capa-
ble calculator or the PC calculator provided in
Accessories.)
Setting value C=(A+B)/2
(8) Confirm that the error rate value is 498 or
less in each channel.
(9) Check the tolerance of adjustment. Shift the
adjustment value against the setting value by
±60h.
Conform that the error rate is 3,000 or less in
each channel. When the error rate is over
3,000, recheck the adjustment procedure
from (4).
(For example, when the adjustment value is
"9ED", ±60h is "A4D" and "98D". So, shift the
value to "A4D" and "98D", and check the tol-
erance of error rate adjustment.)
(10) Return the adjustment value to the setting
value C, and Press the JOG dial to store the
adjustment data.
Oscilloscope
Self-recording
tape
Fig. 3.5.2 (2)
Fig. 3.5.2 (1) SP VCO Menu
Fig. 3.5.2 (4) Consept of the adjustment
SBE waveform (abnormal)
Narrow pulse trains appear uniformly Brightness
is low.
Fig. 3.5.2 (3)
Error
rate
VR DATA Decrease Increase
Value A Value B
Freeze the image Freeze the image
Value C
Adjustment
Point
SBE waveform (abnormal)
Bright parts appear randomly on the waveform.
Adjusted EVR data value
Error rate display
Upper row : CH-1
Lower row : CH-2
– – – A D J U S T M E N U – – –
1 0 6 . M E S P V C O
V R D A T A : 0 8 D F H
S E T D A T A : 0 8 D F H
6 5 5 3 5
6 5 5 3 5