JVC HR-V610EX Service Manual page 13

4.3 Electrical adjustment
Note:
The following adjustment procedures are not only neces-
sary after replacement of consumable mechanical parts
or board assemblies, but are also provided as references
to be referred to when servicing the electrical circuitry.
In case of trouble with the electrical circuitry, always be-
gin a service by identifying the defective points by using
the measuring instruments as described in the following
electrical adjustment procedures. After this, proceed to
the repair, replacement and/or adjustment. If the required
measuring instruments are not available in the field, do
not change the adjustment parts (variable resistor, etc.)
carelessly.
4.3.1 Servo circuit
4.3.1.1 Switching point
Signal (A1) • Stairstep signal
(A2) • Alignment tape(LP, stairstep, PAL) [MHPE-L]
Mode (B) • PB
Equipment (C) • Oscilloscope
Measuring point (D) • VIDEO OUT terminal (75Ω terminated)
• TP106 (PB. FM)
External trigger (E) • TP111 (D. FF)
Adjustment part (F) • Jig RCU: Code "5A"
Specified value (G) • 6.5±0.5H
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 mea-
suring points (D1) and (D2).
(3) Set the VCR to the manual tracking mode.
(4) Adjust tracking 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.4-3a Switching point
4.3.1.2
Signal
Mode
Measuring point (D)
Adjustment part (F)
Specified value (G) • minimum noise
Adjustment tool (H)
(1) Record the signal (A2) in the mode (B1), and play back
the recorded signal.
(2) Set the VCR to the manual tracking mode.
(3) Set the VCR to the FWD slow (+1/6x) 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 (-1/6x) mode.
(8) Repeat steps (1) to (7) in the mode (B2).
Note:
• 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.
4.3.2 Syscon circuit [EX, EY, EZ MODELS]
Notes:
• When perform this adjustment, remove the Mechanism
assembly.
4.3.2.1
Signal
Mode
Equipment
Measuring point (D1)
Adjustment part (F)
Specified value (G)
V.sync
(1) Connect the frequency counter to the measuring point
(D1).
(2) Connect the short wire between the short point (D2) and
Vcc (5V).
(3) Short the leads of capacitor (D3) once in order to reset
the microprocessor of the Syscon.
V. rate (4) Disconnect the short wire between the short point (D2)
and Vcc then connect it again.
(5) Adjust the Adjustment part (F) so that the output frequency
becomes the specified value (G).
Slow tracking preset
(A1) • Ext. input
(A2) • Color (colour) bar signal [PAL]
(B1) • SP
(B2) • LP
• TV-Monitor
• Jig RCU: Code "71"or "72"
• Jig RCU [PTU94023B]
Timer clock
(A1) • No signal
(B) • EE
(C) • Frequency counter
• IC3001 pin 44
(D2) • IC3001 pin 103
(D3) • C3054 + and -
• C3025 (TIMER CLOCK)
• 1024.008 ± 0.001 Hz
(976.5549 ± 0.0010 usec)
(No.YD010)1-13