Service and troubleshooting
EST3 Installation and Service Manual 8.21
Table 8-13: 3-ASU Audio Source Unit Troubleshooting
Problem Possible cause
Remote Microphone trouble 1. Wrong or missing EOL resistor on microphone key input
2. No supervisory tone on DC current on remote microphone
audio output
3-FTCU Firefighter Telephone Control Unit
Table 8-14: 3-FTCU (3-ASU/FT) Firefighter Telephone Control Unit Troubleshooting
Problem Possible cause
Unit does not respond
No RX or TX LED activity
1. Power or data connectors loose or connected wrong on Rail
Chassis Interface Card
2. Ribbon cable between Rail Chassis Interface Card and
3-FTCU loose or defective
3. Ribbon cable between 3-FTCU main board and cover loose
or defective
4. Defective 3-FTCU
Signature modules do not
switch telephones correctly
1. Network data riser open, shorted, or wired incorrectly
2. TB2 on the CPU loose or wired incorrectly
3. Defective 3-FTCU
4. Signature module has incorrect label, personality code, or
device type
5. Defective Signature module
Low telephone volume level 1. More than five handsets active at one time
2. Phone riser open, shorted, or wired incorrectly
3. Connector TB1 on 3-FTCU loose
4. Defective telephone
Call displayed by LCD doesn’t
match connected call
1. Signature module incorrectly labeled in rule
2. Signature module misidentified or installed in wrong location
SIGA audio amplifiers
The following material refers to these amplifier models:
• SIGA-AA30 Audio Amplifier
• SIGA-AA50 Audio Amplifier
Note: At publication time, these modules were not approved for
use in UL 864 9th edition applications. Call Technical Support to
determine the current approval status of the modules.
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