Guardian Telecom Inc.
Installation & Operation
TBA Models
9.11. Optional ringing from PTTs
The PTTs inputs can be used to operate the speaker as a microphone with the jumpers on J21 at
the “RELAY” position. The PTTs can also be used to directly activate the “Ringer” output with a
jumper on J21 at the “RINGING” position for that station.
As all of the stations PTT input circuitry locations are populated on the PCBA, it is possible to add
extra “Ringer Switches” at unused station PTT locations without affecting the operation of the Talk
Back Amplifier system.
To prevent the “RINGER” switch from interfering with normal PTT action when it being used as a
“Ringer”: remove the jumper on J21 for “RELAY” on any position used as a “RINGER” input.
9.12. Replace the TBA enclosure top panel
Turn the AC Power Switch to OFF. Mark the potentiometer positions with a marker on the PWBA
mounted adjustments. Note the front panel Volume control positions or numbers for future use.
Replace the TBA enclosure top panel using the six screws removed earlier.
10. Locations of adjustments for the TBA
The sketch below gives the approximate locations of the adjustments for the TBA. These adjustment
locations are also labeled on the TBA.
Figure 15 - Adjustment Locations
ansformer top
with a large label to caution other installers that these are not standard connections.
10.1. Audio transformer tap adjustments
The audio output transformers are all connected with 0 and 8 Ohms on the input and COM and 325
Ohms on the output for normal operation. If these positions are changed, mark the tr
Page 21
