Lectrosonics UM400a - Manual (Page 15)

Frequency Synthesized UHF Belt-Pack Transmitter
Rio Rancho, NM 15
Before going through the following chart, be sure that you have a good battery in the transmitter. It is important that
you follow these steps in the sequence listed.
Symptom Possible Cause
TRANSMITTER BATTERY LED OFF 1) Battery is inserted backwards.
2) Battery is dead.
NO TRANSMITTER MODULATION LEDs 1) Gain control turned all the way down.
2) Battery is in backwards. Check power LED.
3) Mic capsule is damaged or malfunctioning.
4) Mic cable damaged or mis-wired.
RECEIVER RF LAMP OFF 1) Transmitter not turned on.
2) Transmitter battery is dead.
3) Receiver antenna missing or improperly positioned.
4) Transmitter and receiver not on same frequency. Check
switches/display on transmitter and receiver.
5) Operating range is too great.
6) Transmitter antenna not connected
NO SOUND (OR LOW SOUND LEVEL), 1) Receiver output level set too low.
RECEIVER INDICATES PROPER AUDIO 2) Receiver output is disconnected; cable is defective
MODULATION or mis-wired.
3) Transmitter is not set to same frequency as receiver. Check that
frequency select switches on receiver and transmitter match.
4) Sound system or recorder input is turned down.
DISTORTED SOUND 1) Transmitter gain (audio level) is far too high. Check mod level
lamps on transmitter and receiver as it is being used.
(Refer to Operating Instructions - Adjusting Gain)
2) Receiver output may be mismatched with the sound system or
recorder input. Adjust output level on receiver to the correct
level for the recorder, mixer or sound system.
3) Excessive wind noise or breath “pops.. Reposition microphone
and/or use a larger windscreen.
HISS AND NOISE -- AUDIBLE DROPOUTS 1) Transmitter gain (audio level) far too low.
2) Receiver antenna missing or obstructed.
3) Transmitter antenna missing or folded against housing.
4) Operating range too great.
EXCESSIVE FEEDBACK 1) Transmitter gain (audio level) too high. Check gain adjustment
and/or reduce receiver output level.
2) Transmitter too close to speaker system.
3) Mic is too far from user’s mouth.
Troubleshooting