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4.2.2 FM waveform linearity
Signal
(A1)
• Alignment tape(SP, stairstep, PAL) [MHPE]
(A2)
• Alignment tape(LP, stairstep, PAL) [MHPE-L]
Mode
(B)
• PB
Equipment
(C)
• Oscilloscope
Measuring point (D)
• TP106 (PB. FM)
External trigger (E)
• TP111 (D.FF)
Adjustment part (F)
• Guide roller [Mechanism assembly]
Specified value (G) • Flat V.PB FM waveform
Adjustment tool (H)
• Roller driver [PTU94002]
(1) Play back 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) Set the VCR to the manual tracking mode.
(4) Make sure that there is no significant level drop of the V.PB
FM waveform caused by the tracking operation, with its
generally parallel and linear variation ensured. Perform the
following adjustments when required. (See Fig. 4-2c.)
(5) Reduce the V.PB FM waveform by the tracking operation.
If a drop in level is found on the left side, turn the guide roll-
er of the pole base assembly (supply side) with the roller
driver to make the V.PB FM waveform linear.
If a drop in level is on the right side, likewise turn the guide
roller of the pole base assembly (take-up side) with the
roller driver to make it linear. (See Fig. 4-2c.)
(6) Make sure that the V.PB FM waveform varies in parallel
and linearly with the tracking operation again. When re-
quired, perform fine-adjustment of the guide roller of the
pole base assembly (supply or take-up side).
(7) Unload the cassette tape once, play back the alignment
tape (A1) again and confirm the V.PB FM waveform.
(8) After adjustment, confirm that the tape wrinkling does not
occur at the roller upper or lower limits. (See Fig. 4-2b.)
[Perform adjustment step (9) only for the models equipped
with SP mode and EP (or LP) mode.]
[Perform adjustment step (9) only for the models
equipped with SP mode and EP (or LP) mode.]
(9) Repeat steps (1) to (8) by using the alignment tape (A2).
Improper
(a) GUIDE ROLLER
(b) GUIDE POLE
Fig.4-2b
4.2.3 Height and tilt of the A/C head
Note:
• Set a temporary level of the height of the A/C head in ad-
vance to make the adjustment easier after the A/C head
has been replaced. (Refer to the SERVICE MANUAL
No.86700 [MECHANISM ASSEMBLY].)
Signal
Mode
Equipment
Measuring point (D1)
External trigger (E)
Adjustment part (F)
Proper
Specified value (G) • Maximum waveform
(1) Play back the alignment tape (A).
(2) Apply the external trigger signal to D.FF (E), to observe the
(3) Set the VCR to the manual tracking mode.
(4) Adjust the AUDIO OUT waveform and Control pulse wave-
A/C head
Proper waveform variation
Improper waveform variation
Up
Down
B
A
D
C
Fig.4-2c
(A)
• Alignment tape(SP, stairstep, PAL) [MHPE]
(B)
• PB
(C)
• Oscilloscope
• AUDIO OUT terminal
(D2)
• TP4001 (CTL. P)
• TP111 (D.FF)
• A/C head [Mechanism assembly]
AUDIO OUT waveform and Control pulse waveform at the
measuring points (D1) and (D2) in the ALT mode.
form by turning the screws (1), (2) and (3) little by little until
both waveforms reach maximum. The screw (1)
and (3) are for adjustment of tilt and the screw (2) for azi-
muth.
Head base
(2)
(1)
(3)
Fig.4-2d
Roller driver
Guide roller
(supply side)
AUDIO OUT
CTL. P
(No.YD002)1-19
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