4.2.11 External Speed Reference
An external clock (reference oscillator) can be used to control the speed of
the MTR-90III capstan motor. When the SPEED MODE switch is set to EXT
position, a suitable input signal must be applied to P/N18 of the EXT CLOCK
input connector (a 25 pin Honda connector on the MTR-90III rear panel) or
P/N20 of the Parallel I/O Connector (37 pin connector on the MTR-90III rear
panel). The reference frequency is 9,600 Hz, and should be at TTL level (0 V
low, +5 V high), approximately a 50% duty cycle; a sine wave source may be
used at a level of about 10 Vp-p. Do not feed 9.6 kHz signals to the EXT
CLOCK and PARALLEL I/O connectors at the same time.
When the external reference is in use, the HIGH/LOW SPEED SELECT switch
still operates although tape speeds (15/30 ips or 7.5/15 ips) vary
proportional to the deviations of the clock input from the reference frequency.
When using SMPTE time code synchronizers, the SMPTE-CUE slide switch
(on the back of the upper card cage mother board near the #24 card
connector) should be turned on to activate Lifter Defeat. If the MTR-90III is
being used for 16 track operation, a jumper cable will have to be installed to
join the 3-pin Molex connector adjacent to this switch to a similar connector
on the same circuit board located between the #16 and #17 card connectors
(#8 and #9 for 8 track operation).
Detailed information on using time code synchronizers with the MTR-90III is
available from the manufacturer of the equipment or by contacting OTARI.
Section 4 Operation
4 - 10
October 1990
MTR-90III Operation and Maintenance Manual
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