12
Electrical Connections
The wiring for various electrical and electronic accessories is designed to be simple and straightforward. Your NGT-
12.5 is shipped with the encoder and axis drive cables already plugged into their respective components. Refer to
wiring descriptions below to learn the function and installation of each cable.
Connecting Auxiliary Devices
All other connections should be made prior to plugging in the power cable.
Right Ascension Motor Cable
This longest cable (30") is run from the Command Center's RA jack, along the frame, and terminates at the motor
located next to the drive roller on the base assembly.
Declination Motor Cable
This cable runs from the Command Center's Dec jack, along one yoke arm, terminating at the motor located near the
declination tension adjustment knob.
Disconnect this cable at the Command Center prior to removing the ring
assembly from the base assembly.
Right Ascension Encoder Cable
(8192 tics/rev CW)
This shortest cable (9") terminates in a 4-conductor modular phone plug that connects to the right ascension encoder
jack, attached to the polar bearing.
Declination Encoder Cable
(8192 tics/rev CW)
This cable terminates near the declination bearing which is opposite the declination motor. It utilizes a 4-conductor
modular phone plug that connects to the declination encoder jack. Disconnect this cable at the Encoder jack prior to
removing the ring assembly from the base assembly.
Power Cable
A cigarette lighter cord is provided to permit connecting the NGT-12.5 to a 12- to 15-volt DC power supply (such as an
automobile battery or portable power pack). A wall transformer is also included to provide 12vDC by connecting to a
110vAC/60Hz supply (220vAC/50Hz for appropriate destinations). The power input is reverse-polarity protected.
Optional Battery Pack
Although the batteries are charged at the factory just prior to shipment, we recommend that they be topped off with a
one- to two-hour charge before their first use. Because these are lead-acid batteries (and not nickel-cadmium), they
do not have a memory effect. While an 8-12 hour charge should be adequate after a single evening's use, 12 -24
hours should restore their capacity after they have triggered the low-voltage alarm described on
page 14
.
If the batteries will not be used for an extended period, they should be recharged approximately every three months.
If they are allowed to remain in a discharged state for too great a time (approximately four to six months), they may
lose their ability to sustain a charge, and require replacement.
Summary of Contents for NGT-12.5
Page 2: ......
