Kirby Air Control System manual Testing Communications, KMACS 5 MANUAL

2.5.2 TESTING COMMUNICATIONS

Test the communications between the diver and the KMACS 5. With the communicator (R) switched on, turn the speaker switch to “on” and adjust the volume to a comfortable level for both the diver and the KMACS 5 operator. In the 2 wire mode, the communicator functions similarly to a citizens band radio; i.e., the KMACS 5 operator must de- press the push to talk switch to speak to the diver. In the 4 wire mode, the communicator functions like a telephone conference call; i.e., everyone on the line can hear and speak to everyone else. In either mode, for the diver to talk top side, it is only necessary for him to speak into the oral/nasal mi- crophone in his mask or helmet. If two divers will be working together, test the cross-talk functions at this time as well.

To extend the life of the battery, it is recommended that the communications be used in the 4 wire mode. Operation as a 2 wire system uses relays inside the unit which will cause a higher battery drain.

CAUTION: In the 2 wire mode, when the push-to-talk switch is depressed, the KMACS 5 operator should keep all of his communications short (10-15 seconds) at any one time. This allows the diver to call for assistance if necessary.

Plug the earphone connectors on the diver’s umbili- cal into the earphone jacks on the communicator. Plug the microphone connectors on the umbilical into the microphone jacks on the communicator. This will create a 4 wire system/round robin system. Test the system and adjust all volume controls.

Fig. 8 Preliminary testing of the umbilical with a volt-ohm meter to check for continuity.

KMACS 5 MANUAL

Unplug the earphone connectors on the diver’s um- bilical from the communicator and reinstall them in the connectors attached to the plugs for the micro- phone. This will change the communicator to a 2 wire system. Test this system and adjust volumes.

If there are no communications, recheck all of the connections to ensure they are tight at each junction. If the KMACS 5 has been operating in a coastal en- vironment, look for corrosion on the top side connec- tors which may interfere with the communications. If corrosion is evident, disassemble the connectors, clean, and retest. If corrosion is heavy, replace the top side connectors.

Substitute other masks or umbilicals to test for failures in the microphones or umbilical. Substitute one piece of new gear at a time to track the fault down. If the fault is in the mask or helmet, replace the earphones or microphones as needed.

If the fault is in the umbilical, disconnect the umbili- cal and carefully inspect its length for damage. Look for obvious nicks or cuts.

If there is physical damage to the outside of the communications wire there probably is a break on the inside, too. Test the continuity of the wire end-to end with a volt-ohmmeter.

Uncoil the umbilical and lay it out flat with the two ends close to each other. Set the volt-ohmmeter to resistance (ohms) and hold one probe to one prong on an umbilical connector plug and touch the other probe from the meter to the wires (or connector) at the opposite end of the diver’s umbilical. Upon locat- ing the other end of the same wire, the meter should indicate zero resistance, i.e., there is a complete, uninterrupted circuit. If touching none of the wires at the other end of the umbilical produces a zero reading and all readings are infinity (∼), this indicates a complete break in the wire. If the reading is some- where between zero and infinity, and changes as the umbilical is moved, this indicates a partial break, and communications will be intermittent. In either case, a waterproof splice must be made in the wire.

© 2003 KMDSI Document # 041112001 11