Samsung CFTD2085X/SMS, Service Manual

Page: 33 / 112

Disassembly and Reassembly
Samsung Electronics 3-23
3-5-2 Linearity adjustment
(Guide roller S, T adjustment)
1) Playback the Mono Scope alignment tape (SP
mode).
2) Observe the video envelope signal on an oscil-
lo-scope (triggered by the video switching
pulse).
3) Make sure the video envelope waveform (at its
minimum) meets the specification shown in
Fig. 3-5-4.
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. 3-5-5 does not meet the
speci-fication, adjust the guide roller S up or
down.
5) If the section B in Fig. 3-5-5 does not meet the
speci-fication, adjust the guide roller T up or
down.
Fig. 3-5-4 Envelope Waveform Adjustment
a
a b c d
c,b,d/a 63%
b
c
d
Fig. 3-5-5 Adjustment Points
A B
A B
H'D SWITCHING
PULSE
ENVELOPE
6) Play back the Mono Scope alignment tape (SP mode).
7) Connect an oscilloscope CH-1 to the Envelope and CH-2 to the H’D SW Pulse for triggering. (TPM01)
8) Turn the guide roller heads with a flat head ( ) driver to obtain a flat video RF envelope as shown in
Fig. 3-8.
Fig. 3-5-6 Guide Roller S, T Height Adjustment
IDEAL ENVELOPE
S HEIGHT TOO HIGH
S HEIGHT TOO LOW T HEIGHT TOO HIGH T HEIGHT TOO LOW
GUIDE ROLLER S
GUIDE ROLLER T