Figure 2-9.
Helical scan, tape transport
c. With a tape in position, the machine properly terminated with a monitor,
and all controls set for playback, you may test the machine. With a picture on the
monitor and sound from the speaker, an overall evaluation of the unit's playback
quality can be made.
(1) With a known good tape on the machine and if, during playback, severe
picture dropout occurs, check for dirty brushes or commutator, or a clogged video
head.
(2) The tracking control may be out of adjustment and require adjustment.
Excessive horizontal motion of the monitor picture during a playback could be
caused by low-frequency flutter, excessive capstan drive pressure, or possibly a
damaged capstan drive wheel.
(3) If the head drum (fig 2-8) will not rotate, check power and fuses or
check to see if the tape is too tight around the drum.
(4) If the picture
appears noisy, or the playback level is low but the
sound is normal, then check
for a clogged video head. Also, check for a rough edge
on a video head gap which
possibly can be corrected by contouring tape.
If the
problem persists, it may be
necessary to replace the head.
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