Lectrosonics MM400a - Manual - Manual (Page 8)

MM400A
BATTERY INSTALLATION
WARNING! TO PREVENT INTERNAL CORROSION!
If the transmitter is wet (either due to immersion or high levels of perspiration), BEFORE opening any covers or connectors,
carefully blot the transmitter dry with a clean paper towel or cloth. Remove all moisture. After opening any connector or cover,
carefully blot up any remaining moisture that may have remained around the seal. THIS IS IMPORTANT! DO NOT CLOSE
ANY COVER OR CONNECTOR BEFORE MAKING CERTAIN THERE IS NO MOISTURE IN OR NEAR THE OPENING.
After use, it is important to store the transmitter in a dry place with all access doors and connectors opened to allow any internal
humidity to evaporate. Specifically, open the battery door, the frequency cover plate and fully unscrew and remove the
microphone connector before storing. Do NOT store wet and do NOT store sealed. If moisture is sealed inside the unit it has
nowhere to go other than to chemically react with and destroy components and the printed circuit board.
The transmitter is powered by a standard lithium, NiMH
or alkaline AA 1.5 volt battery. Standard zinc-carbon
batteries marked “heavy-duty” or “long-lasting” will
not work. NiMH rechargeable batteries will only provide
2 hours of operation and will run down quite abruptly.
Alkaline batteries provide over 2 hours of operation with
some warning. Lithium batteries can be used to provide
up to 4.5 hours. The battery status circuitry is designed
for the voltage drop over the life of lithium batteries.
To open the battery compartment, unscrew and remove
the battery cover. Take note of the polarity marked on
the case showing the location of the positive (+) and
negative (-) terminals. The positive (+) battery terminal
goes into the transmitter. You can see the small contact
hole inside the battery compartment with the cover
removed.
Insert the battery correctly and screw the Battery
Compartment Cover into the transmitter body. If the
battery is inserted incorrectly, the cover will not screw in
easily and the unit will not work.
MICROPHONE RF BYPASSING
Some mics require RF protection to keep the radio 2 WIRE MIC 3 WIRE MIC
signal from affecting the capsule, even though the
transmitter input circuitry is already RF bypassed.
If the mic is wired as directed, and you are having
difficulty with squealing, high noise, or poor frequency
response; RF is likely to be the cause.
The best RF protection is accomplished by installing RF
bypass capacitors at the mic capsule. If this is not
possible, or if you are still having problems, capacitors
can be installed on the mic wires inside the TA5F con­
nector housing.
Leaded capacitors: P/N 15117
Install the capacitors as follows: Use 330 pF capacitors. Leadless capacitors: P/N SCC330P
Capacitors are available from Lectrosonics. Please
All Lectrosonics lavalier mics are already bypassed and
specify the part number for the desired lead style.
do not need any additional capacitors installed for proper
operation.
INPUT JACK WIRING
2k
6V Mic Bias
30uF
2k
FB 100 2k
To Mic Amp
2.2nF
330pF 330pF
Mic
Jack FB
Battery Compartment Cover
Battery Compartment
CAPSULE
CAPSULE
SHIELD
AUDIO
SHIELD
AUDIO
BIAS
MIC
CONNECTOR
MIC
CONNECTOR
Preferred locations for bypass capacitors
Alternate locations for bypass capacitors
LECTROSONICS, INC. 8