T25-35SA Troubleshooting Information T25-35SA Subadible Tone Decoder Troubleshooting Information


Please try this first but call for technical support at (708) 352-2166 if you cannot solve the problem.

NO AUDIO OUTPUT: Check your wiring connections. The DB-9 connector is usually reliable, but it can sometimes seem locked in but not be making a good contact. See if the LEVEL CHECK LED (on the PC board) is glowing. Make sure the INPUT LEVEL control (on the PC board) is properly adjusted.

MISSING TONES: Be sure the LEVEL CHECK LED is glowing green all the time during programming. It should flash red on program peaks. Adjust INPUT LEVEL control until this condition is observed. Be sure 25 Hz and 35 Hz tones are on the program audio being sent to the unit.

MISSING TONES: See above. Be sure the DETECT LED is staying on for the entire duration of the tone. If it blinks off at any time, the tone level is right at the detection threshold. Increase the 25 Hz SENSE or 35 Hz SENSE controls one turn at a time clockwise (1 dB per turn) until a solid indication is given by the DETECT LED, then one more.

FALSE TRIGGERING: Input levels are too high or program audio is not properly highpass filtered at the source. Adjust the INPUT LEVEL control counterclockwise until the LEVEL CHECK LED is green most of the time with frequent red flashes. Output level should be approximately 0 dBm into 600 ohms. If levels are OK then adjust 25 Hz SENSE or 35 Hz SENSE one turn counterclockwise until false triggering stops. This may cause detection problems if the network audio is not properly filtered at the source. Reducing detector sensitivity can only correct for very high tone levels.

POOR REJECTION: This is caused by the network tones being off frequency with respect to the T2535. If you can, measure the frequency of the tones being sent by the network and then align the unit to these frequencies. Normal tone rejection is -20 dB or better. DO NOT ADJUST THE DETECTOR TUNING UNLESS YOU ARE EXPERIENCING LITTLE OR NO TONE REJECTION AT THE OUTPUT. You will need test equipment to set it back to normal!