User manual

depends on the model type. Refer to the connector
assignments on pages 40 and 41.
In addition, consult the safety instructions on
pages 4 … 12.
To prevent uncontrolled movements of the
servos connected to the receiver system,
during startup
first switch on the transmitter
and then the receiver.
When turning off the model,
first switch off the receiver
and then the transmitter.
When programming the transmitter, make sure that an
electric motor cannot accidentally start. When a gas
motor with an automatic starter is used, make sure
that it cannot unintentionally start. For safety's sake,
disconnect the drive battery or the fuel supply.
Receiver power supply
To safely operate the model, a reliable power
supply is required. If the receiver voltage
shown on the transmitter display always drops
or is generally (too) low even though the linkage moves
freely, the battery is full, the cross-section of the battery
connecting cable is sufficient, and the transition resist-
ance that the plug-in connectors is minimal, etc.,
observe following:
First make sure that the battery is fully charged when
initially operating the model. Make sure that the
resistance of the contacts and switches is low. Measure
the voltage drop over the installed switch cables under
a load since even robust, new switches cause a voltage
drop of up to 0.2 V. This value can be several times
higher due to aging and oxidation of the contacts. In
addition, constant vibration and shaking of the contacts
also gradually increases the transition resistance.
Furthermore, even small servos such as a Graupner/
JR DS-281 draw a stall current up to 0.75 A when you
stop under load. Four of these servos in a foam seat can
hence draw up to 3 A from the onboard power supply.
Furthermore, servos connected to a 2.4 GHz receiver
receive control pulses more frequently than comparable
receivers in the classic frequency range. This affects
the power consumption of the receiver system as well
as the characteristic of many modern digital servos of
maintaining the last position specified by the last control
pulse until the next pulse arrives.
You should therefore choose a power supply that does
not fail under a high load and always provides sufficient
voltage. To calculate the required battery capacity, add
at least 350 mAh for each analog servo, and at least
500 mAh for each digital servo.
Using this method, a battery with 1400 mAh represents
the absolute minimum for supplying power to a receiver
with four analogue servos. In your calculation, also
include the receiver which requires about 70 mA due to
its bidirectional function.
Apart from the above considerations, it is generally
recommendable to connect the receiver to the power
supply using two cables. As usual, connect cable "1"
to the "12+B-" receiver connector, and cable "2" to the
opposite end of the connector strip labelled "11+B-"
when for example using a switch or voltage regulator
with two power supply cables leading to the receiver.
Between the cable and receiver, you can use a V or
Y cable (order No. 3936.11, see figure) if one or both
receiver connectors also need to be connected to a
servo, speed controller, etc. With the double connection
to the switch or voltage controller, you not only reduce
the risk of a cable rupture but also ensure an even
power supply to the connected servos.
If you connect a separate battery to each battery con-
nector, be sure that each of the batteries has the same
rated voltage and capacity. Never connect different
battery types or batteries with strongly different charges
since this can cause an effect similar to a short circuit.
In such cases for safety reasons, insert voltage stabiliz-
ing elements such as PRX-5A receiver power supplies
between the batteries and receiver:
Aux. function
Y-lead
Order No. 3936.11
PRX stabilised
receiver power supply
Order No. 4136
For safety reasons, never used battery boxes or dry
batteries.
The voltage of the onboard power supply is shown at
the top left of the transmitter display in yellow text:
35
Installation instructions - Receiver power supply
S1006_mz-24.3.en.indd 35 17.12.2014 15:21:23