Sony SLV-D990PB / SLV-D990PE / SLV-D990PR / SLV-D995PE Service Manual ▷ View online
6-7
b. ACE HEAD TILT ADJUSTMENT
1) Playback a blank tape and observe the position of the tape at the lower flange of tape guide.
2) Confirm that there is no curl or wrinkle at the lower flange of tape guide as shown in Fig. 6-9 (B).
3) If a curl or wrinkle of the tape occurs, slightly turn the screw (A) tilt adjust on the ACE head ass’y.
4) Reconfirm the ACE head height.
2) Confirm that there is no curl or wrinkle at the lower flange of tape guide as shown in Fig. 6-9 (B).
3) If a curl or wrinkle of the tape occurs, slightly turn the screw (A) tilt adjust on the ACE head ass’y.
4) Reconfirm the ACE head height.
(A)
(B)
(BAD)
WRINKLE
(GOOD)
Fig. 6-9 Tape Guide Check
c. AUDIO AZIMUTH ADJUSTMENT
1) Load alignment tape (Mono scope) and playback the 6KHz signal.
2) Connect channel-1 scope probe to audio output.
3) Adjust screw (B) to achieve maximum audio level. (See Fig. 6-7)
2) Connect channel-1 scope probe to audio output.
3) Adjust screw (B) to achieve maximum audio level. (See Fig. 6-7)
6-8
d. ACE HEAD POSITION (X-POINT) ADJUSTMENT
1) Playback the alignment tape (Color bar)
2) Press the “TEST” botton on VCR MAIN PCB to set the adjustment mode. (See Fig. 6-2)
3) Press the “0, 5” remote control buttons, then adjustment is operates automatically. (See Fig. 6-1)
4) Connect the CH-1 probe to “Envelope” the CH-2 probe to “H’D switching pulse” and then trigger to CH-1.
5) Insert the (-) driver into the X-Point adjustment hole and adjust it so that envelope waveform is maximum.
2) Press the “TEST” botton on VCR MAIN PCB to set the adjustment mode. (See Fig. 6-2)
3) Press the “0, 5” remote control buttons, then adjustment is operates automatically. (See Fig. 6-1)
4) Connect the CH-1 probe to “Envelope” the CH-2 probe to “H’D switching pulse” and then trigger to CH-1.
5) Insert the (-) driver into the X-Point adjustment hole and adjust it so that envelope waveform is maximum.
Test point
: W568 (Audio Output)
W569 (Envelope)
W570 (H’D S/W -Trigger)
W571 (Control Pulse)
W570 (H’D S/W -Trigger)
W571 (Control Pulse)
Fig. 6-10 Location of Test point (VCR Main PCB-Top View)
AUDIO OUTPUT
CONTROL PULSE
HEAD SWITCHING
ENVELOPE
6-9
(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 oscilloscope (triggered by the video switching pulse).
3) Make sure the video envelope waveform (at its minimum) meets the specification shown in Fig. 6-11.
2) Observe the video envelope signal on an oscilloscope (triggered by the video switching pulse).
3) Make sure the video envelope waveform (at its minimum) meets the specification shown in Fig. 6-11.
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.
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. 6-12 does not meet the specification, adjust the guide roller S up or down.
5) If the section B in Fig. 6-12 does not meet the specification, adjust the guide roller T up or down.
5) If the section B in Fig. 6-12 does not meet the specification, adjust the guide roller T up or down.
a
a b c d
c,b,d/a 63%
b
c
d
Fig. 6-11 Envelope Waveform Adjustment
A
B
A
B
H'D SWITCHING PULSE
ENVELOPE
Fig. 6-12 Adjustment Points
6-10
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.
8) Turn the guide roller heads with a flat head (
7) Connect an oscilloscope CH-1 to the “Envelope” and CH-2 to the “H’D SW Pulse” for triggering.
8) Turn the guide roller heads with a flat head (
) driver to obtain a flat video RF envelope as shown in Fig. 6-13.
Fig. 6-13 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
Fig. 6-14 Video Envelope Rising when Operation mode Changes from RPS to Play Mode
ENTRANCE SIDE ENVELOPE
(3) Check Transitional Operation from RPS to Play
Check transition from RPS mode to play mode : Using a pre-recorded SP tape, make sure the entry side of envelope comes to an appropriate
steady state within 3 seconds (as shown in Fig. 6-14).
If the envelope waveform does not reach specified peak-to peak amplitude within 3 seconds, adjust as follows :
steady state within 3 seconds (as shown in Fig. 6-14).
If the envelope waveform does not reach specified peak-to peak amplitude within 3 seconds, adjust as follows :
1) Make sure there is no gap between the supply roller lower flange and the tape.
If there is a gap, adjust the supply guide roller again.
2) Change operation mode from the RPS to the play mode (again) and make sure the entry side of envelope rises within 3 second.
If there is a gap, adjust the supply guide roller again.
2) Change operation mode from the RPS to the play mode (again) and make sure the entry side of envelope rises within 3 second.
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