Operating instructions

❑ Logic cable for optional auto locator:
(50-pin Cannon D connectors). Insert the male end of this cable into the
MTR-90III and the female end into the Auto Locator. Then secure with
the two screws supplied.
NOTE: This cable is supplied with the optional CB-148 Auto Locator.
❑ AC power cord:
(3-pin mains plug plus threaded 3-pin female connector). Orient the
special connector on the cable so its key matches the MTR-90III chassis
connector, and insert. Then screw the connector coupling securely to
lock the cord in place. Refer to Figure 2-9 for details on the wiring of the
AC power line plug.
Figure 2-9
AC Power Cord Wiring
CAUTION: Do not plug the other end of the power cable into the AC mains
until it is verified that the actual mains voltage meets the specified
requirements for the MTR-90III as labeled on its rear panel. Refer to §2.6 for
details on conversion of the power supply. Also, check to make sure the
MTR-90III power switch is turned off before plugging in the power cord. This
circuit breaker is located on the power supply front panel, behind the left
door on the front of the machine and is off when the lever is pressed
downward. Refer to §4.2.1 Step 3 for instructions on powering up the unit.
2. Connect the buss output connectors from the console to the MTR-90III
input connectors (10 kΩ load impedance, floating) and the MTR-90III
output connectors ( 5 Ω source impedance, floating) to the line inputs of
the console. To avoid hum-inducing ground loops, be sure to follow a
sensible grounding scheme such as telescoping shields, e.g., single
common ground point (connect shields at the console, not at the tape
machine or vice versa, then connect a 12 AWG ground wire from the
MTR-90III frame to the console mother board or patch bay ground. A
600 Ω termination of the MTR-90III is unnecessary.
NOTE: Audio connections are made via 2-conductor shielded cables
terminated in XLR-type connectors. These cables are not provided with the
MTR-90III but are commonly available (standard professional microphone
cables) or may be wired as shown in Figure 2-10.
1
}
2
WHITE
ACTIVE
BLACK
GREEN — GROUND
3
Figure 2-10
XLR Cable Wiring for Audio Connections
MTR-90III INPUT XLR-3-31
MTR-90III OUTPUT XLR-3-32
PIN 2 AUDIO SIGNAL LOW
PIN 3 AUDIO SIGNAL HIGH
PIN 1 SHIELD
Section 2 Installation
2 - 10
October 1990
MTR-90III Operation and Maintenance Manual