Servo Circuit; Switching Point; Slow Tracking Preset; Video Circuit - JVC HR-J271MS Service Manual

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3.2

SERVO CIRCUIT

3.2.1 Switching point

Signal (A1) • Stairstep signal
(A2) • Alignment tape (SP,stairstep,PAL) [MHPE]
Mode (B) • PB
Equipment (C) • Oscilloscope
Measuring point (D1) • VIDEO OUT terminal (75Ø terminated)
(D2) • TP106 (PB. FM)
External trigger (E) • TP111 (D.FF)/slope : –
Adjustment part (F) • Jig RCU: Code "5A"
• 6.5 ± 0.5H
Specified value (G)
Adjustment tool (H) • Jig RCU [PTU94023B]
(1) Play back the signal (A1) of the alignment tape (A2).
(2) Apply the external trigger signal to D.FF (E) to observe
the VIDEO OUT waveform and V.PB FM waveform at the
measuring points (D1) and (D2).
(3) Press the channel buttons (+, –) simultaneously to enter
the manual tracking mode. This also brings tracking to
the center (centre).
(4) Adjust tracking by pressing the channel buttons (+, –) so
that the V.PB FM waveform becomes maximum.
(5) Set the VCR to the Auto adjust mode by transmitting the
code (F) from the Jig RCU. When the VCR enters the
stop mode, the adjustment is completed.
(6) If the VCR enters the eject mode, repeat steps (1) to (5)
again.
(7) Play back the alignment tape (A2) again, confirm that the
switching point is the specified value (G).
Trigger point
Switching point
Fig. 3-2-1a

3.2.2 Slow tracking preset

Signal (A1) • Ext. input
(A2) • Color (colour) bar signal [PAL]
(A3) • Color (colour) bar signal [NTSC]
Mode (B1) • VHS SP -
(Notes) (B2) • VHS LP -
(B3) • VHS SP -
(B4) • VHS EP -
Measuring point (D) • TV-Monitor
Adjustment part (F) • Jig RCU: Code "71" or "72"
Specified value (G) • Minimum noise
Adjustment tool (H) • Jig RCU [PTU94023B]
(1) Record the signal (A2) in the mode (B1), and play back
the recorded signal.
(2) Press the channel buttons (+, –) simultaneously to enter
the manual tracking mode. This also brings tracking to
the center (centre).
(3) Set the VCR to the FWD slow (+1/6x) mode.
3-2
V.sync
V. rate
Switching point
(PAL)
(NTSC)
Digitized in Heiloo Netherland
(4) Transmit the code (F) from the Jig RCU to adjust so that
the noise bar becomes the specified value (G) on the TV
monitor in the slow mode.
(5) Set the VCR to the Stop mode.
(6) Confirm that the noise bar is (G) on the TV monitor in
the slow mode.
(7) Repeat steps (3) to (6) in the REV slow (–1/6x) mode.
(8) Repeat steps (1) to (7) in the mode (B2).
(9) Record the signal (A3) in the mode (B3), and play back
the recorded signal.
(10) Repeat steps (2) to (7).
(11) Repeat steps (9) and (10) in the mode (B4).
Notes:
• For FWD slow (+1/6x) playback, transmit the code "08"
from the Jig RCU to enter the slow playback mode, and
transmit the code "D0" for REV slow (–1/6x) mode.
• For 2 Head models, adjustments should generally be
performed in SP recording mode. However, for 2 Head
models equipped with LP (or EP) mode, adjustments
should be performed in LP (or EP) recording mode
only.
3.3

VIDEO CIRCUIT

3.3.1 AUTO PICTURE initial setting

Signal (A1) • Ext. input
(A2) • Video: Optional
(A3) • VHS tape
• EE ¥ Auto adjust (SP/LP REC ¥ PB)
Mode (B)
Adjustment part (F) • Jig RCU : Code "58"
Specified value (G) • STOP mode
Adjustment tool (H) • Jig RCU
(1) Insert the cassette tape (A3).
(2) Set the VCR to the Auto adjust mode by transmitting the
code (F) from the Jig RCU. When the VCR enters the
stop mode, the adjustment is completed. When the VCR
enters the eject mode, repeat steps (1) to (2) again.
Note:
• When this adjustment is performed for models that are
equipped with the NTSC Record mode, the color (col-
our) system of the VCR will compulsorily become
"PAL". When it is required to return the color (colour)
system to "AUTO", this can be achieved by operating
the VCR menu or transmitting the code "60" from the
Jig RCU.
4/5/2017