5. To shift the CTL waveform, press [PROGRAM ]either at the beginning or end of track as shown in
or [PROGRAM ] button. Then make sure thatFig. M9.
the maximum output position of PB FM envelope
signal becomes within ?2ms from preset position.Dropping envelope level at the beginning of track.
Good
FM envelope signal
2msCenter Position
Fig. M8
CTL signalDropping envelope level at the end of track.
FM envelope output signal
is adjusted at maximum.
No Good
FM envelope output signal is low.
Fig. M7
Fig. M9
6. Set the Tracking Control Circuit to the preset posi-
tion by pressing [PROGRAM ] button and thenEnvelope is adjusted properly. (No envelope drop)
[ O ] (VCR) button on the unit.
1-C. Checking/Adjustment of Envelope
Waveform
Purpose:
To achieve a satisfactory picture, adjust the Guide
Rollers so that the PB FM envelope becomes as flat
as possible.
Fig. M10
Symptom of Misalignment:
If the envelope output is poor, noise will appear in theNote: Upon completion of the adjustment of Guide
picture. The tracking will then lose precision and the
Rollers [2] and [3] (Refer to Fig. M3), check the X
playback picture will be distorted by any slight varia-
Value by pushing the [PROGRAM ] or [PROGRAM
tion of the Tracking Control Circuit.
] buttons on the unit alternately, to check the sym-
1. Connect the oscilloscope to TP301 (C-PB) on themetry of the envelope. Check the number of pushes to
Main CBA. Use TP504 (RF-SW) as a trigger.ensure preset position. The number of pushes of the
[PROGRAM ] button on the unit to achieve 1/2 level
2. Playback the Gray Scale on the Alignment Tape
of envelope should match the number of pushes of the
(FL6NS8). Set the Tracking Control Circuit to the
[PROGRAM ] button on the unit from center. If
preset position by pressing [PROGRAM ] button
required, redo the X Value Alignment.Ž
and then [ O ] (VCR) button on the unit. Adjust the
height of Guide Rollers [2] and [3] (Fig. M3, Page
2-3-3) watching the oscilloscope display so that the
envelope becomes as flat as possible. To do this
adjustment, turn the top of the Guide Roller with
the Guide Roller Adj. Screwdriver.
3. If the envelope is as shown in Fig. M7, adjust the
height of Guide Roller [2] (Refer to Fig. M3) so that
the waveform looks like the one shown in Fig. M9.
4. If the envelope is as shown in Fig. M8, adjust the
height of Guide Roller [3] (Refer to Fig. M3) so that
the waveform looks like the one shown in Fig. M9.
5. When Guide Rollers [2] and [3] (Refer to Fig. M3)
are aligned properly, there is no envelope drop
2-3-4E9BA1MA |
ACEC
TOSHIBA
