INSTALLATION MANUAL
89000007
Page 2-9
15 Nov 2013
© Honeywell International Inc. Do not copy without express permission of Honeywell.
Figure 2-4. KT 74 Connector Positions
2.6 Interface
Details
2.6.1 Power
Input
The power supply can be 11 to 33 VDC; no voltage adjustment is required.
Contacts 11 and 12 on the 24-way connector are both available as power
inputs. This is for compatibility reasons only – internally the two are
connected together, and in most installations only one need be connected to
the power supply.
Use a 3 AMP circuit breaker for power supply protection to the KT 74.
2.6.2 Lighting Bus Input
The KT 74 will adjust the brightness of the front panel switch lighting
according to the voltage on the lighting bus input. Two lighting bus inputs are
provided on the 24-way connector to accommodate aircraft with 14- or 28-
volt lighting systems. When the lighting bus operates at 28 volts, connect the
bus input to Contact 3, and leave Contact 2 unconnected. When the lighting
bus operates at 14-volts, connect the bus input to Contact 2. In this case
Contact 3 can be left unconnected, but for backwards compatibility may also
be grounded instead with no effect.
If no lighting bus input is detected, the KT 74 will automatically control the
front panel lighting based on the ambient light sensor.
