Receiver Installation; Receiver Power Supply - GRAUPNER mxs-8 Handbuch

Receiver installation

Several notices and suggestions for installing remote
control components in a model are provided below.
1. Wrap the receiver in a foam rubber pad that is at least
6 mm thick. Attach the foam rubber to the receiver
with rubber bands so it will be protected against vibra-
tion, a hard landing or crash.
2. All switches must be installed such that they are not
affected by exhaust gases or vibration. The switch
knob must be freely accessible over its entire range
of movement.
3. Mount servos on rubber bushes with hollow brass
bearings to protect them from vibration. Do not screw
the fastening screws in too tightly as this would de-
feat the purpose of the rubber bushes, i.e. to protect
against vibration. This arrangement provides security
and vibration protection for your servos only when the
servo fastening screws are tightened to the proper ex-
tent. The figure at right shows how a servo is moun-
ted properly.
4. The brass bearings are to be inserted in the rubber
bushes from below.
Befestigungslasche
Schraube
Gummitülle
Messing-Hohllager
5. Servo arms must be free to move throughout their
entire range of motion. Ensure that no linkage parts
would be able to hinder servo arm motion.
The sequence in which servos are connected to the
receiver depends on the type of model. Follow the con-
nection layouts provided for this on page 21.
Also observe the safety notices provided on pages 3-6.
In order to prevent uncontrolled movements of servos
connected to the receiver during startup:
42 42 Receiver installation

Receiver power supply

always first switch on the transmitter
and then the receiver;
and when finished with operation:
first switch off the receiver
and then the transmitter.
When programming the transmitter, be sure that electric
motors cannot start running without control or that a
combustion motor equipped with automatic starter cannot
start up unintentionally. To ensure safety, disconnect the
receiver's drive battery or, in the case of a combustion
motor, disconnect the fuel supply.
Receiver power supply
Safe operation of a model depends on factors such as
a reliable power supply. Despite smooth linkage, a fully
charged battery, battery leads with adequate cross-sec-
tion, minimum contact resistances at connectors, etc.,
the transmitter display could indicate repeated drops in
receiver voltage or a receiver voltage level that is general-
ly low or too low; in such a case, consider the following:
Give primary attention to fully charged batteries when
model operation is to be started. Ensure that the
resistance across the contact surfaces of connectors and
switches is indeed low. If necessary, measure the voltage
drop across installed switch cables when they are under
load because even new heavy-duty switches can cause a
voltage drop of up to 0.2 V. This value can increase by a
multiple as a consequence of contact aging and oxidati-
on. Constant vibration and jarring also takes their toll on
contacts in time, resulting in a steady increase of contact
resistance.
And even rather small servos like a Graupner/SJ DES-
281 can draw off as much as 0.75 A of current when it is
blocks under load. Just four of these servos in a 'foamie'
model can therefore overload the on-board power supply
by as much as 3 A.
You should therefore choose a power supply which will
not break down under greater loads but rather always
deliver sufficient voltage. To estimate the required battery
capacity you should always figure on at least 350 mAh
for every analog servo and at least 500 mAh for every
digital servo.
Applying this rule, a battery with 1400 mAh, for example,
would be the absolute minimum required to power a
receiver system with a total of four analog servos. But