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This is done so you can refer back to their positioning as you assemble the new set
into the lower servo case. Clean all the old lubricant from the servo case in both the
lower and upper case components. Be aware of small chunks of gear material that
may be lodged in the lubricant and get it all cleaned out. Apply servo gear lube to the
shafts and assemble the geartrain applying lube to ail gear components. When
complete pop the case top back on and tighten up the case screws
CAUTION: Do not force the case top back on. If it will not fit back on smoothly,
chances are the gears were installed incorrectly.
How to by-pass the BEC circuit on the HAS-02M/03MB and HP-2RNB receivers
The Hitec AM, model HAS-02MB, HAS-03MB and HP-2RNB receivers are built with
a BEC or battery eliminator circuit built into the battery port of the receiver This will
limit the amount of power some of the larger servos can draw from the receiver.
It is suggested that using these receivers with large power consumption servos like
the HS-805BB, HS-815BB or the high end, premium coreless motor servos and
digital servos, a “Y’ harness be used to connect the receiver battery / switch harness
and servo to the receiver. Typically this is done by connecting one of the upper “Y”
connectors to the servo, the other upper connector to the switch harness and the
lower “Y” connector into receiver port 1, 2 or 3,. depending on what channel you wish
the servo to operate.
This will allow the BEC to be bypassed, your large servo will always have power and
the rest of the servos and the receiver will be powered from the port you plug the “Y
into
Too Many Servos
Modern coreless and digital servos have impressive torque values. This takes a lot of
power. Receivers are capable of delivering only so much power to the servos plugged
into it before the voltage draw down caused by the servo power consumption falls
belowwhat the receiver requires to “hear” the signal from the transmitter. When this
occurs a “glitch” will result from loss of signal to the receiver. Large aircraft can
easily use 6 or more powerful servos with some 1/3rd scale planes having multiple
servos per control surface. There are several answers to this issue. Many modellers
choose to use two receivers and others power the servos with a separate battery
from that of the receiver.
The point here is to be cautious when “Y” harnessing or “ganging” powerful servos
together. Using larger capacity NiCad batteries as well as Heavy Duty switch
harnesses are highly recommended in these applications.
Defects, others than on cases or gears
If demages or defects occour, others than on cases or gears, we would like to
strongly discourage you from ever working on. This is best left to authorized service
technicians with the proper equipment.
Servo Trouble Shooting
Servo makes a grinding noise or acts erratic: Open the case and remove the gears.
Examine them for broken teeth. If broken, replace with a new gear set.
Checking Servo Centering: Remove the servo from the plane or vehicle. With the arm
still attached to the servo, place an ink dot towards the end of the wheel and another
one on the case, these should be lined up for a reference point. Plug the servo into
the receiver and move the corresponding transmitter gimbal stick or wheel from stop
to stop. After each movement, check the reference points for alignment
Servo hums under load: This can be normal. The servo is trying to hold position
against the force of a load. If it hums when no load is applied, try loosening the servo
case screws a quarter to a half a turn
Servo gets hot: Get out the fire extinguisher! Check the servo wiring, it should match
the receiver being used. The motor could be stalled due to a failed geartrain. Actually
several things could be wrong, this sounds like a candidate for the service
department.
USA/UK
This document contains general servo information and frequently asked questions
regarding the use and care of Hitec servos. Please note that modifying your servo will
void the warranty.
Pulse Data
AII Hitec servos require 3-5V peak to peak square wave pulse. Pulse duration is from
0.9 ms to 2.1 ms with 1.5 ms as centre. The pulse refreshes at 50 Hz (20 ms).
Voltage Range
AII Hitec Servos can be operated within a 4.8V-6V. range. Only the HS-50 operates
exclusively with 4 NiCad cells ( 4.8 volt ).
Wire Color Meanings
On all Hitec servos the Black wire is ‘ground’ the Red wire (center) is ‘power’ and the
third wire is ‘signal’.
Direction of Rotation
AII Hitec servos turn Clockwise direction ( CW ).
The Appropriate Servo for Your AppIication
One of the most frequently asked questions is “What servo should I use for.....”.
While there have been many magazine articles that attempted to provide a general
rule of thumb to answer these questions, we offer you the following suggestions.
1. Servos are rated for Speed and Torque. In many cases, Hitec will create one servo
and then gear it for speed and sacrifice torque, then create its twin, geared for
torque at the sacrifice of speed, i.e. 525/545, 625/645, 925/945.
2. If you are not sure, it is better to have more torque than you need, as torque is
your friend.
3. When in doubt ask your peers about servo application questions. Look at what
others are using in comparable applications. Usually the kit manufacturer will
suggest a servo of a certain physical size and torque value specification in the
aircraft, car or boat plans. It is wise to follow their guidelines.
4. Even though micro servos like the HS-82 may offer 380z/in of torque, they are not
appropriate for larger powered aircraft due to the flight loads placed on the control
surfaces during flight. The geartrain can fail under excessive flight loads.
Smaller servos have thinner gears that are inherently more fragile than those of
“standard” sized servos.
Digital servo Information
In addition to our line of analog servos, Hitec produces several digital servo products.
These powerful servos offer programmable features such as, direction of rotation,
center point, end points, failsafe option, speed and dead bandwidth adjustment using
Hitec’s proprietary programmer and servo tester device.(Model HFP-10).
What are the advantages of digital servos:
1.
Instantaneous Response
The digital micro processor sends out signals five times faster than analog
servos. This results in much quicker response.
2.
Precision Resolution
There are many more steps in the digital format compared to the conventional
analog version. This means the servo is capable of finer adjustments.
3.
Enormous Standing Torque
The standing torque of the digital servos is 3 times that of the analog counterpart.
Check it out, try moving the transmitter stick or wheel and at the same time hold
the servo horn to keep it from twisting. You will not be able to prevent the horn
from turning. Muy fuerte mi amigo!
Special Warning for Digital servos !!!
1.
If you accidentally plug in the Hitec “S” type digital servo into the old Airtronics
(Sanwa) receiver, this will blow up the servo circuits so please take special care.
2.
Digital servos consume tremendous amount of power, so dry batteries cannot be
used at all. Use large capacity NiCd batteries or better yet NiMH batteries.
3.
Do not use BEC system built in most 2 channel receivers.Make sure you bypass
the BEC for stable operation.
Servo Maintenance
Changing Gears
Hitec offers gear sets for all our servos and these are available from your local hobby
shop or from a mail order retailer. To replace the gears on any servo, carefully lay out
the new gears on a clean work surface to have them available for re-assembly. You
will also need a supply of servo gear lubricant. We suggest the Hitec lube part #
58450. Loosen or remove the screws located on the bottom of the servo case enough
to pop the upper case off and expose the gears. If any gears or shafts are stuck in
the upper case, remove them and plug them back into position on the lower case.
Now carefully remove the gears while placing them in approximate order on your work
surface in front of you .