Operating instructions
TROUBLESHOOTING 
The following are general guidelines and initial suggestions. If a problem persists, please refer to the section, 
SERVICE AND REPAIR. 
Telephone interface won’t stay 
connected. 
Software control panel spontane-
ously disconnects from LecNet 
I can hear the remote parties on both 
the telephone and codec interfaces, 
but they are having trouble hearing 
each other. 
The TH3 appears to connect but I’m 
not getting any sound. 
I have trouble interrupting the other 
party, or the other party has trouble 
interrupting me. 
The TH3 works fine, but I am very 
aware of the dynamic gain adjust-
ments as the other party speaks. I 
find it somewhat distracting. 
The front panel switches don’t work. 
[Factory Reset Procedure] My TH3 is 
not working and I am unable to gain 
access to a PC right now. 
The automatic disconnect feature is disconnecting the line inappropriately. 
Ensure that the telephone line is connected to the telephone line jack and 
not the telephone set jack. Ensure that the line is live by connecting a 
telephone to the telephone set jack and getting a dial tone. If you are 
connecting via a PBX or have call waiting enabled, it may be necessary to 
disable the automatic disconnect feature via the software control panel. 
All LecNet software must share the serial port so that multiple software 
control panels may be operated simultaneously.  The TH3 software will 
close the serial port temporarily whenever the software is minimized or 
inactive. It will reconnect when reactivated. 
It is possible to set receive levels too low and then compensate with more 
amplification. You will hear the remote parties but they will not hear each 
other properly. Also, the echo suppression will not work optimally in this 
situation.  To correct, use the meters to set the receive levels of both the 
telephone and codec interfaces, as described in the LEVEL SETTING 
PROCEDURE. 
Verify that privacy is not engaged (privacy led is off), and the interface is 
connected (connect led is on). Make sure the potentiometers on the front 
panel are not turned all the way down. Check all interconnects and mixer 
settings. If the telephone interface is to be used, verify that an external 
telephone, connected to the telephone set jack, is able to raise a dial tone 
when the TH3 telephone interface is not connected.  If the meters are 
moving, check for problems with the local sound reinforcement system. 
With the software control panel, verify that the supplementary echo cancel-
ler inserts are not active and that all inputs and outputs are enabled.  If all 
else fails, try restoring the TH3 to factory settings, as described at the end 
of this section. 
This problem occurs when the transmit and receive levels are not set 
equitably, or when the LecNet anti-echo adjustment is set incorrectly. 
Repeat the steps in the LEVEL SETTING PROCEDURE to correct. 
When the TH3 is set up optimally, the echo suppression and LecNet anti-
echo operation is fairly subtle. It is possible that your ears are exceptionally 
well conditioned to detect the effects, so you are not comfortable with the 
default settings. It is also possible that the TH3 could be adjusted for better 
performance. Repeat the LEVEL SETTING PROCEDURE to make sure 
that all levels are set correctly. If operation does not improve, try a smaller 
amount of echo suppression from the software control panel, or try reduc-
ing the LecNet anti-echo setting on the front panel. 
If the “switches disabled” led is on, the front panel switches have been 
disabled. They can be enabled again using the software control panel or by 
restoring factory settings, as described at the end of this section. 
The TH3 may be reset to its factory default settings by holding down both 
codec receive volume buttons as the power is turned on.  The TH3’s LecNet 
address remains unchanged, but all other settings revert to their defaults. 
This will work even if the front panel switches had been disabled previously. 
The switches will no longer be disabled after this procedure. 
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