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7) Envelope Check
1. Make recordings and playback the tapes T-120 and
T-160 in SP and SLP modes and make sure the
playback output envelope meets the specifications
shown in Fig. 1-7-7.
2. In recording/playback the tape with a T-120, the
video envelope should meet the specification as
shown in Fig. 1-7-12.
Note:
• Check for both modes, SP and SLP. Also check for
AFM envelope when using a Hi-Fi model.
A
B/A ≥ 0.55
≥ 120mV
B
Fig. 1-7-12 Envelope output and output difference
3. If the performance does not meet both specifications
above 1. and 2. above, replace the head assembly
(cylinder) assembly.
4. Set the VCR to Rec mode (SLP) with the T-120 tape
loaded (at the beginning part) and check operation of
the synchronous editing recording.
5. If picture noises are observed at the starting position
of the editing, check for transitional operation (f).
8) Tape Damage Check
1. Playback the T-160 tape in the Play mode, CUE
mode, Review mode and the frame advance mode,
and check each guide for wrinkle.
2. If excessive tape wrinkle is observed at the mode
shown below, perform the associated adjustments in
each mode. Also the parts described in ( ) may need to
replace.
a. Playback mode
Tape damage at the S, T-guide rollers section
(c) Linearity adjustment (Slider assembly)
Tape damage at No. 8 guide flange
(a) ACE head assembly rough adjustment
(Pinch assembly)
Tape damage at lower flange of No. 3 guide
(f) Check for transitional operations
from Review to Play, and Slot-In to Play
(Tension lever)
B
b. Review mode
Tape damage at No. 8 guide
(a) ACE head assembly rough adjustment
(Pinch assembly, No. 9 guide lever,
capstan motor assembly)
Tape damage at the guide rollers
Guide roller adjustment
(or Slider assembly replacement)
c. Frame advance mode
Tape wrinkle at No. 8 guide
(c) Linearity adjustment
(Pinch assembly, capstan motor assembly)
9) Maximum AFM Envelope Output Point Check
(Hi-Fi Model)
1. Playback the SP mode 3 MHz video signal and the
400 Hz AFM signal on the alignment tape.
2. Trigger the oscilloscope with the video switching
pulse, adjust the tracking control and check the
control pulse phase at the maximum video envelope
(A ch) output point.
3. Make sure the control pulse phase difference among
each maximum point of AFM envelope, A ch and B
ch is within ± 3 ms with the above point used as the
basic reference.
Note:
• If the phase difference exceeds 3 ms, replace the head
assembly (cylinder).
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