Table of Contents
Advertisement
I NTERCHANGEABI L ITY CH ECKS A N D ADJUSTMENTS
1 . 6
No.
Item
Adjustment parts
- - - - - -\--
Before using costly Al ignment tape, use a spare tape and confi rm correct operation of the tape transport.
- - - - - - - ---i - - -
F M waveform
a
a
�
� �
�
0.7,
Osci l l o scope di s pl a y
Tri g ger poi n t
Fig. 1 -6-1
I
Drum entrance
D
s= � � s= �
C C
C C
Fig. 1 -6-2
I
Drum exi t
(I n correct)
Fig. 1 -6-3
1 - 1 0
Operating mode
- -
-
- -
and
a
�
'!_
0.5
0.5
FM envelope
Si m ul a ti o n
C C C
I
I
I
I
I
C C C
(I n correct)
( C orrect)
Drum entrance
Si m ul a ti o n
( C orrect)
Drum exit
Description
1 )
Connect osci l l oscope to the FM OUT testpoint of the video
playback circuit. Trigger the osc i l loscope external l y w ith the
signal from the drum f l i pflop ( D - F F or F F ) testpoint. Set the
trigger slope to m i nus ( - ) .
2) P l a y the M H-1 Al ignment tape a n d adjust the tracking for
maxi m u m FM waveform output. Refer to F ig . 1 -6- 1 . Confirm
the relationsh i ps indicated i n the figure for maximum output
(a) . m i n imum center output ( b ) . m inimum output at the drum
i ntake (c) and m i n imum output at the drum output (d ) .
3) Adjustment is req u i red i f the above specifications a re not ful
fi l l ed . Even when these are fulfil led, check that the F M wave
form varies l i nearly overa l l . If not, sl ight deviation in track ing
wi l l cause a l arge proportional l evel drop to result in noise
appearing in the picture. Therefore, in this condition, proceed
to the fol lowi.ng checks and perform adjustments where neces
sary.
4) Operate the tracking adjustment between m i n imum and maxi
mum outputs of the F M waveform. Observe the portion of the
waveform corresponding to the drum i ntake (see F ig. 1 -6-2 ) .
As the tracking i s adjusted, although t h e gain may i n crease o r
decrease, the geometric shape o f th is part of t h e waveform
should remai n consistent .
If the shape varies, as shown by the i n correct examples i n the
figure, carefully perform adjustment of the supply guide ro l l er
height.
Next observe the portion of the waveform corresponding to
5)
the drum output (see Fig. 1 -6-3 ) . w h i l e operati ng the tracking
adjustment. This should also vary only i n gain, but not i n
shape.
If the shape varies, as shown by the incorrect examples in the
figure, carefu l l y perform adjustment of the take-up guide
rol ler height.
6) Check the overa l l FM waveform .. F i ne-adjust both g u ide ro l l ers
so that variation is as m i n imum and l i near as possible.
7) Observe the tape tr�t the gu ide rol lers and guide poles.
Confirm absent"En'.>f tape creasing or curl i ng.
Confirm that the tape properly rides at the lower flange of the
supply guide pole. Carefully adjust the guide pole height if
necessary. This adjustment is important and affects F M wave
form response.
If creasi ng or curl i ng is observed at the take-up guide po le,
carefu lly adjust the audio/control head incli nation so that the
tape rides properly at the lower flange of the gu ide pole.
F i na l l y, agai n check the FM waveform.
Advertisement
Table of Contents
