Servo Circuit; Switching Point; Slow Tracking Preset; Dynamic Drum Preset - JVC HR-S9800U Service Manual

FDP
Fig. 3-1-5a

3.2 SERVO CIRCUIT

3.2.1 Switching point

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Signal (A1) Stairstep signal
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(A2) Alignment tape(SP, stairstep, NTSC) [MHP]
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Mode (B) PB
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TBC: OFF
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Equipment (C) Oscilloscope
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Measuring point (D1) VIDEO OUT terminal (75Ø terminated)
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(D2) TP106 (PB. FM)
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External trigger (E) TP111 (D.FF)/slope : –
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Adjustment part (F) Jig RCU: Code "51" or "52"
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Specified value (G) 8.0 ± 0.5H
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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) Transmit the code (F) from the Jig RCU to adjust so that
the trigger point of the VIDEO OUT waveform is changed
from the trailing edge of the V.sync signal becomes the
specified value (G).
(6) Set the VCR to the stop mode or eject mode.
Trigger point
Switching point
Fig. 3-2-1a

3.2.2 Slow tracking preset

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Signal (A1) Ext. input
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(A2) Color (colour) bar signal [NTSC]
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Mode (B1) S-VHS SP
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(B2) S-VHS EP
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Measuring point (D) TV-Monitor
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Adjustment part (F) Jig RCU: Code "71" or "72"
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Specified value (G) Minimum noise
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Adjustment tool (H) Jig RCU [PTU94023B]
3-2
EVR mode
V.sync
V. rate
Switching point
(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 mode.
(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 mode.
(8) Repeat steps (1) to (7) in the mode (B2).
Note:
• For FWD slow (+1/6 × ) playback, transmit the code "08"
from the Jig RCU to enter the slow playback mode, and
transmit the code "D0" for REV slow (–1/6 × ) mode.

3.2.3 Dynamic Drum preset

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Signal (A1) Alignment tape(EP, stairstep, NTSC) [MHP-L]
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(A2) Ext. input
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(A3) Stairstep signal
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Mode (B1) EP 3× (FWD) search
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(B2) EP
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(B3) EP 1/6× (FWD) slow
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Equipment (C) Oscilloscope
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Measuring point (D) TP106 (PB. FM)
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External trigger (E) TP111 (D.FF)/slope : +
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Adjustment part (F) Jig RCU: Code "A0" or "A1"
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Specified value (G) Flat V.PB FM waveform
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Adjustment tool (H) Jig RCU [PTU94023B]
•
Digit-key remote controller
(1) Play back the signal (A3) of the alignment tape (A1).
(2) Apply the external trigger signal to D.FF (E) to observe
the V.PB FM waveform at the measuring point (D).
(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 mode (B1).
(6) Adjust tracking by pressing the channel buttons (+, –) so
that the V.PB FM waveform becomes half of the maxi-
mum value.
(7) Transmit the code (F) from the Jig RCU to adjust so that
the V.PB FM waveform becomes the specified value (G).
(8) Set the VCR to the PB mode once, set the VCR to the
mode (B1) again and confirm that the V.PB FM wave-
form is the specified value (G). If the specified value (G)
is not obtained, repeat step (7).
(9) Record the signal (A3) in the mode (B2), and play back
the recorded signal.
(10) Repeat steps (3) to (8), for perform step (5) in the mode
(B3).
Fig. 3-2-3a DD preset