Drum Discr. Position - JVC HR-S10EG Service Manual

3.5 SERVO SYSTEM ADJUSTMENTS 3.5.3. Drum DISCR. position
([0][3] SERVO board) Mode : REC
Signal : Color bar
3.5.1 Drum pulse level Oscilloscope :TP7
Mode : REC 1. Short TP21 to TP-GND.
Signal : Color bar 2. Adjust R69 to stabilize the sampling pulse with respect
Oscilloscope 7 PS to the trapezoid,
Note: Drum Servo must be locked. 3. Conform following items.
1. Adjust R97 so that the positive and negative pulse »
become 0.7 £0.1 Vp-p ves aft
: t, = 3.2£0.5 msec t3= 40 msec
a
+
b
a=b=0.7401V
DRUM PULSE
Fig. 3-3
Fig. 3-5
Pe Mode : PB
Mode
:
Signal
: Alignment tape (MH-2 Stairsteps)
Signal
: Color bar
Oscilloscope
: VIDEO OUT
Oscilloscope —: TP3
1. Trigger the oscilloscope externally (— slope) with the
signal from TP11.
2. Adjust R95 to position the trigger point 6.5 + 0.5 H
before V. syne.
1. Short TP22 to TP-GND.
. Adjust R15 to stabilize the sampling pulse with respect
to the trapezoid. All this time, a slow drift at the rate of
less than 40 msec in 5 second is acceptable.
Nn
Vv. SYNC
ama 5+0.5H———+|
Sampling pulse slow drift ii,
Fig. 3-4 SWITCHING POINT (CH-1)
3. Conform following items. Fig. 3-6
az 5.0V
3. Set the trigger slope of the oscilloscope to plus (+).
tz = 3.2 40.5 msec
ti/ts =1
t4 = 40 msec
4. Adjust R93 to position the trigger point 6.5 + 0.5 H
before V. sync.
Vv. SYNC
6.5+0.5H
SWITCHING POINT (CH- ATU
Fig. 3-7
3-3