4170t-ams.ib.rev0.doc
Page 5 of 14
17/10/2007
Configuration
Transistor drive to relays:
The AMS-4170T comes standard with links LK2, 4 & 6 installed. This allows TTL logic to directly drive the relays
via transistor drive circuits. It is not necessary to use TTL logic to drive the transistor drive circuits, however,
grounding on the control port is all that is needed.
Direct drive to relays:
Provision has been made for bypassing the transistor relay drivers if required. This may be desirable in situations
where switching is to be initiated by alarm circuits with relay outputs.
The relay driver circuit can be bypassed as follows:
1. Remove links LK 2, 4 & 6.
2. Hard wire shorting links in positions LK 3, 5 & 7.
Ensure that only one link is installed of each pair so that the circuit is set for either TTL or direct operation, but not
both.
Relay grouping:
Each video and audio channel is equipped with its own driver circuit. However each circuit is capable of driving all
three sets of relays if required. Links LK 8, 9 & 10 provide a means of inter-connecting the relay sets so that only
one or two control inputs are required.
Some useful configurations are:
Unison operation:
All three circuits switch from one control signal.
1. Remove links LK 2, 4 & 6.
2. Connect links LK 8, 9 & 10.
3. Control is via SK 5 pin 1 to ground (SK 5 pin 4).
In order for the front panel switches to work as intended, AMS-4170T should be run in unison operation.
Separate video & stereo audio operation:
1. One control signal for video, and separate control signal for stereo audio.
2. Connect LK 9 & 10.
3. Control for video is via SK 5 pin 1.
4. Control for stereo audio is via either SK 5 pin 2, or SK 5 pin 3.
If controlling video and audio separately the front panel switches will only work on the video part of the circuit.
Input termination:
No terminations are provided on the module so that the switcher can function in changeover mode. For 2 x 1
switcher applications the following terminations should be installed.
Video:
Output A only is used and should be terminated at connected equipment.
Output B should be terminated in 75 Ohms (or 50 Ohms if being used for 50 Ohm RF signals) using a BNC
termination plug.
Audio:
Outputs A only are used and should be terminated at connected equipment.
Output B may be terminated if desired by connecting termination resistors to the connector on the rear
assembly of the module. The resistor values should be chosen to match the characteristic impedance of the
rest of the connected audio system. For example for balanced 600 Ohms, two 300 Ohm resistors should be
used.
In most modern audio systems a low output impedance of approximately 40 Ohms and input impedances of
greater than 10 kOhms are used. If this is the case no termination of the unused audio output is required.
