Samsung SVR-639 Service Manual page 63

2-2-2 Linearity adjustment
(Guide roller S, T adjustment)
1) Playback the Mono Scope alignment tape (SP mode).
2) Observe the video envelope signal on an oscillo-
scope (triggered by the video switching pulse).
3) Make sure the video envelope waveform (at its
minimum) meets the specification shown in
Fig. 2-6.
If it does not, adjust as follows :
Note :
a=Maximum output of the video RF envelope.
b=Minimum output of the video RF envelope at the
entrance side.
c=Minimum output of the video RF envelope at the
center point.
d=Maximum output of the video RF envelope at the
exit side.
4) If the section A in Fig. 2-7 does not meet the speci-
fication, adjust the guide roller S up or down.
5) If the section B in Fig. 2-7 does not meet the speci-
fication, adjust the guide roller T up or down.
6) Play back the Mono Scope alignment tape (SP mode).
7) Connect an oscilloscope CH-1 to the Envelope and CH-2 to the HÕD SW Pulse for triggering.
8) Turn the guide roller heads with a flat head (
GUIDE ROLLER S
Samsung Electronics
IDEAL ENVELOPE
S HEIGHT S HEIGHT
TOO HIGH TOO LOW
Fig. 2-8 Guide Roller S, T Height Adjustment
b
Fig. 2-6 Envelope Waveform Adjustment
H'D SWITCHING
PULSE
ENVELOPE
) driver to obtain a flat video RF envelope as shown in Fig. 2-8.
T HEIGHT
TOO HIGH
Alignment and Adjustment
a
c
a b c d
63%
c,b,d/a
A B
A B
Fig. 2-7 Adjustment Points
T HEIGHT
TOO LOW
GUIDE ROLLER T
d
2-3