Double Horse 9116
Troubleshooting

Compiled from contributions by owners of the DH9116 RC helicopter and members of RC Groups Discussion Forums via the
“Double horse 9116 Heli Thread" and
"The new Double Horse 9116 Heli Thread"

Dedicated to Mick, aka „Stormforce“, who did a fantastic job with his
“Double Horse 9116 Technical Manual”, downloadable at http://customers.skymesh.net.au/~mat...ech_manual.pdf

Thanks a bunch, Mick, you did a remarkable job tutoring new RC-pilots like me and making them understand their 9116 MUCH better!

Rest in Peace, mate!

-mike-
aka “mikefromgermany”

 

Let’s get started:

You didn't listen to others or asked nobody before,
got blinded by advertisements and well spoken promises and
finally had been badly misled by the hobby-grade-look of this bird?
(like me..)

So you got yourself a 9116, dialed it in, flew it
and now
encountered problems or did a crash and broke something.
As a beginner you have no clue where to begin.

Maybe here’s something to solve it.

Important:
For all problems and solutions listed below it is required the heli was or is dialed in according to the "Double Horse 9116 Technical Manual" (link above)

If you can’t find anything regarding your problem, feel free to ask at
"The new Double Horse 9116 Heli Thread"

FOD
Frequently Occuring Damages

TX doesn't bind

You switched the heli on, the TX also, the beeping stopped but the red LED still is flashing instead of going solid?

When binding, make sure the throttle trim is set to neutral or it's lowest point and the throttle stick is at it's lowest point. Switch the tx off, plug in the battery, but don't switch it on. Then hold the tx in your left hand (assuming it's in mode 2) and hold the throttle down with your thumb, switch on the tx, then before it starts beeping, switch on the heli and quickly place it on a level surface, it should be bound when you hear the servo's flutter into life and align themselves with the settings in the tx programming.

If it doesn't bind, go through the procedure again, but this time, once the tx stops beeping, move the throttle stick to full and back down again. Sometimes when the heli won't bind because the gyro hasn't initialized, this action re-arms the gyro. Most of the times it works.

TX still doesn't bind

Tried everything above. Still nothing. PCB light flashes fast then slow and stays slow with no bind. Occuring sometimes after a hard crash or even as a DOA.

1. Have a closer look on the soldered connection bridge between main PCB and the Antenna PCB. In the pic it's the black block on lower right.
If DOA, there are often solder-blobs that shorten some pins - my spare PCB was delivered like this (picture below) - or these bridge has cold solder points - just tip every one with an iron.


2. Resolder the connection pins of the crystal (the silver can on antenna-PCB - it can be mounted under the newer PCBs too, then the resolder job is much easier.

Motors shut down when lift off?

If you smoothly increase throttle from zero the motors shut down? Then the reason is a too sensitive "motor overload protection system" - short: MOPS.
It occurs quite often especially with a new main motor, the problem is reduced or goes away over time as the motor got run in.

1. Try bumping your throttle up quickly to around 30-50% to lift off, this bird needs no slow increase of throttle like a big CP heli.
If that doesn't help:
2. Change the motor wires with some heavier gauged ones and get rid of the sockets and plugs (thanks to steve_ and Whizgig)
3. Only if the first two options don't work you should even consider doing the MOPS Bypass (below)

The Heli doesn't stop turning clockwise, even with all trim applied with buttons

Your tail is overpowering the main motor's forces.
This leaves five possibilites:

1. The main motor is dying (most probably)
2. Mechanical issue with the main rotor parts(gears too tight or too loose, friction or binding of the shaft, etc. (regular)
3. The PCB's gyro is sending wrong signals (happens often after some crashes or if it got some moisture)
4. Dull cable connections from PCB to main motor (happens due to wear and vibration)
5. The responsible Mosfet doesn't work right (not likely).

Options:

1. Set the RUD subtrims in the TX up to 120L and try to stop rotation. If it stops the motor is dying. Time to order a new one. If it slows rotation only, install a new main motor instantly.
2. Clean up all primary transmission elements, check for debris/clogging everywhere
3. Do the gyro-test below, if PCB fails, first get a hairdryer and heat the dismounted board up and let it cool down slow. Retest, failing again means you'll need a new PCB
4. Check all cable connections, test resistances, plugs and sockets
5. For specialists only to check - insert new PCB

The Heli doesn't stop turning counter-clockwise, even with all trim applied with buttons

You encounter a lack of tail authority when trying to do a FFF banked right turn (clockwise). The motor can barely manage pushing the tail around. Your tail isn't even able to hold at all?
This also leaves five possibilites:

1. The tail motor is dying (most probably)
2. Mechanical issue with the tail rotor parts (gears too tight or too loose, friction or binding of the shaft, hair/grass clogging etc. (regular)
3. The PCB's gyro is sending wrong signals (happens often after some crashes or if it got some moisture)
4. Dull cable connections or shortages from PCB to rear motor (happens due to wear and vibration)
5. The responsible Mosfet doesn't work right (not likely).

Options:

1. Set the RUDD subtrims in the TX up to 120R and try to stop rotation. If it stops, the tail motor is dying. Time to order a new tail assembly. If it slows rotation only, install a new tail instantly.
2. Clean up all transmission elements, check for debris/clogging everywhere
3. Do the gyro-test below, if PCB fails, first get a hairdryer and heat the dismounted board up and let it cool down slow. Retest, failing again means you'll need a new PCB
4. Check all cable connections, test resistances, plugs and sockets, even dismount the complete tail assembly and check for damaged cable insulations
5. For specialists only to check - insert new PCB

Servo Horn bends and slides up the pushrod

So your servo horns bend and slide up the pushrod? It mostly occurs on aileron servo (right hand side, looking from the tail).
You don't need stronger servo horns - just try one possibility after another:

First reheat the bent servo horn and straighten it (it will last until you get some spares).

Electronic settings:
Set the AILE end points for this servo lower in the TX:
- Hold MENU button 2 seconds, until "MODE" flashes on LCD
- Press MENU twice to get to D/R (rates setting)
- Press SEL (Select) once to get to AILE (Aileron)
- Hold DN (Down) button until it reads 10% less than before
- Flip the rate toggle switch on upper left
- Hold DN (Down) button until it reads 10% less than before
- Hold MENU for two seconds, until the voltage appears again
- Test aileron servo throw, if it still is pushing against moving limits of the swashplate, repeat steps above.
Do the same with the elevator servo if you are having trouble with bending the nylon servo arm there, too. ELEV EPA F is the setting you want to work with.

Mechanical enhancements:
A: Simple swap the servo rod 180 degrees as to how the servo arm is placed on the rod. See the attached picture and you will see the rod is placed so that the rod is now outside the servo arm in relation to the mainframe. It also minimizes friction against the canopy and the chances of hanging up against it.
B: Try to bend the hook of the pushrod more to right angles. (you can see in the picture, too)
C: Do the servo-move mod as stated below.
D: Make a little small plastic washer & glue it onto the pushrod (pictured below, thanks to Rajah235)
E: Mod the pushrod with a dab of solder and form a "fork":

up: modified rod
down: original

Broken main shaft # 9116-06

Crashed and broke one or both pins of the main shaft? No spare part?
A quick repair that reinforces it at the same time:

Shorten the hollow pipe to 73mm (cut from upper side!), then
replace the sheared off blade pivot pins by a single metal rod, 2,4x20mm (you have to drill the remains out, of course) and (optional) reinforce the upper part of the main shaft with a glued in steel rod 2,0x10mm (just shove it in to the top, lowest piece in picture).


If you don't want to shorten the hollow pipe, after drilling the peg remnants out you should use 2 pieces of 2,4mm strong and 8mm long nylon thread (string trimmer / weed eater string works best) and glue them in both holes so that the hollow pipe still fits through the central hole of the main shaft.

Bad vibrations

After a crash you get bad vibrations spooling up, no visible damages?

Check following parts:

1. Hollow Pipe, often slightly bent - barely to be seen - to check remove it and roll it over a glass surface. Rebend in shape until straight again.
2. Flybar, often slightly bent at the weights. Check and bend back straight.
3. Main shaft: often sheared off or bent pins hidden in the blade grip - repair as mentioned above or install new one.

HOW-TO's

Replacing the tail

Take off the canopy and unplug the wires for the tail motor and the tail light from PCB (tail motor cable is blue/white, tail light cable is red/black)
Cut the cable ties holding the wires to the body (2), undo the center screw on each side of the tail block (1) and pull the tail out along with the wiring. Now replace the tail unit in the same way as above in reverse order.

Replacing the main motor

Take off the canopy, unclip the servo linkages on the swashplate (A), undo the retaining screw in the main gear (B), remove the complete rotor head assembly together with the hollow pipe and the main gear (C). Undo the 3 screws on each side on the base of the body (D) and remove the 2 supporting bars (E). Unclip the floor and remove it by expanding the body frame slightly.
Unplug the motor from the PCB and remove the 2 screws holding the motor. Now you can remove it and replace the old motor. Reassemble in reverse order as above.


You will be exchanging a motor at a regular basis (believe me...), to make it much faster next time, do following:
After step (E) take the floor and drill two 5mm (3/16") holes in it, so they line up with the motor screws.
The next time you have to replace the motor all you will have to do is step A to C, then undo the 2 screws and replace the motor.

Improvements
Some improvements you can do to correct some flaws in construction.

Blade balancing

It is always a good idea to balance the main blades. Reduces vibrations and wear and tear on bearings.

A cheap balancing scale is pictured below. You balance the lighter blade with small pieces of tape.

Canopy Spacer

To fix the left servo horn touching the canopy, when the servo is at full throw forward.

Cut 2 pieces of plastic 2mm strong, drill 3 holes in it (you will notice where if you look at the canopy holder) and use these as a spacer.

Canopy Sticker

It makes sense to patch some adhesive tape on a new new canopy where the flybar would hit it. I use a clear, glass-fibre reinforced tape for it - near to invisible and bears some beating from the flybar. It also prevents the flybar crashing through the canopy and smashing the PCB (the gyro especially).

Servo Move Mod

To fix the left servo horn touching the canopy, when the servo is at full throw forward, to fix the slide of servo horn up the pushrod and also to fix the excessive outward flexing of the servo arm.

You'll find the instruction to do it in the tech-manual.
Pictures of my mod:

Tail Boom Bumper

The tail boom denting is caused by the flybar striking it. You will suffer these strikes when you're flying the bird too hard (sudden full stick movements in opposite directions) or crash with throttle applied.
As the tail tube still is straight it's merely a cosmetic problem. But repeated strikes bend the flybar too, causing vibrations.

Some people have put rubber or clear plastic hose over it to protect it, even wine cork.
I took a small piece of packaging foam and fixed it with shrink tube.

Main Blade Grip Washers

Makes better, direct steering performance, blades don’t wobble around any more but are still movable in the grip.

Left picture: The washers for the main blade grip are stamped from 0,15mm thick plastic sheet – outer diameter 9mm, inner diameter 4,5mm.
Right picture: Washers mounted (thanks to OrangeBird)

Low Voltage Buzzer

To get a decent warning before your battery runs down while your bird is 50 feet in the air and starts plunging towards the soil.

Install a Low Voltage Buzzer (~2-5 USD) under the bottom plate with double faced adhesive tape, it weights only 6 grams and it indicates per LED and sound if the voltage per cell is dropping below 3.6V. Plus: the balancer plug is secured.... As stated often enough before: Highly recommended!

MOPS Bypass Mod

As stated above it prevents the sudden shut down of motors when throttling up. These blackouts occure sometimes in the air when you suddenly apply full throttle, too. The problem is reduced and passes over time as the motor got run in. You may also first break your new motor in before thinking of a bypass.
I didn't got any negative effects with stock motors yet.
I recommend doing it only if you stay with the stock motors AND are a good enough flyer to get the throttle quick enough off before you crash.
CAUTION!
You may fry your PCB. You WILL fry it when the motor brushes short due to wear out!
You WILL burn out motors if they are stalled throttled up due to a crash or catching obstacles like grass etc while landing.

Still want to do it?
Connect the two solder points (marked in the picture) of the red MOPS-loop with a blob of solder on the back side of the PCB. Don't cut the silicon insulated wire itself!
You can undo this mod anytime you want.

FAQ

Terms: What the hell are you talking about?

Movements and terms:
Elevators does not mean elevation, it means pitch (nose up and down), ailerons means roll (bank left and right) and rudder means yaw (rotation around the vertical axis). Throttle controls elevation on any fixed pitch heli. Speed is achieved by how much you pitch the nose down (elevators) while holding a consistent elevation by adjusting the throttle.

The heli leans to the right when hovering

The heli leans to the right while hovering more or less motionless in the air - that's caused by the head-construction and pure physics. Don't try to compensate with weight on the left skid etc, this reduces only flight time and maxes tear n' wear.

My range is less than the advertised 100m

100m range is reached only at the very best conditions, without any other 2.4 GHz noise, no obstacles etc. In reality you'll get 50-70m. To enhance reception do not direct the antenna to the bird, a 90° angle to the bird and parallel to ground would be best.

What batteries I should buy for upgrade?

Any 7.4V 2S 800 - 900 mAH 20C Lipo Battery with JST connector and JST-XH balancing plug with following dimensions will fit without modifications: 58 x 30 x 15mm, max weight 50gr.
DON'T add a heavier battery expecting longer flight time with higher capacity. The helicopter only becomes sluggish, overheats its motors, and in most cases flight time shortens noticeably, the added capacity will be countered by the added weight.
The balance will me more orientated to the front, so you'll have to balance it out. You'll definitely wear out the main motor quicker.

My well balanced 9116 starts to spin slightly clockwise as the battery goes down.

It's normal that you have to retrim the rudder while flying when the batterie goes down. That's what the trim buttons are for.

I can't save my settings like subtrims or throttle curves on the TX.

Press MENU for 2 seconds - until the battery voltage is back on screen. All changes you do with the trim buttons are lost when switching the RX off.

The servos jitter when powered up

The servos should make a sudden short flutter or jitter on power up, as they may have moved when you powered down or the arms may have dropped during storage, so when you power up, they settle back to the position the tx has them set to by the user programming. However, if a servo make's a constant noise or the arms constantly move like they are vibrating (jitter) it is from an over excited step motor within the servo, which usually means the servo motor is on it's way out.

How to check functionability of gyro?

1. disconnect main motor
2. turn on heli and TX
3. increase throttle to c.a. 50%
4. holding heli horizontally turn it along it's main shaft axis
5. tail motor should counterfight your movements
6. if it's not - probably gyro is defective

How to balance the heli?

To balance the heli, tie some string or sewing thread to the top of the main shaft above the blades and suspend the heli by the string. If the heli is bias one way or another, you must adjust the heli weight so it hangs level. This may require you to shift the position of the battery, or even add weight to the top of the battery or inside the nose of the canopy. Once the heli is balanced, you can step on to the swash-levelling procedure in Stormforce's Tech-Manual.

My main/tail motor doesn't last long

These motors are cheap, brushed and driven far beyond their construction limits. So don't expect them to last more than 50 flights in general. Sometimes even bad motors are sold that last for only 25 flights. Long hovering sessions will stress your motors even more, ending in even less flights per motor. They also burn out quick if are stalled throttled up. It is always a good idea to stock up 2 main motors and 3 tail assemblies, just in case. You may get more flights out of them when breaking every new motor in.

How to break a new motor in? And why?

When brushes are new, they do not completely touch the commutator. They wear into it, eventually getting a mirror-like finish over the complete contact surface. If you run these already overstressed motors under full power and load before the brushes were fully seated, the brushes got way too hot, and burn out the lubrication embedded within them. The edges of the brush keep breaking off, are uneven and jagged.
To break these motors in, running the motor and just letting the rotor spin at low RPM (20% throttle) for 4-5 minutes does the trick.
Most people probably do this already when they are first messing around with their new bird without even realizing it, sliding it around on the ground.
Brushed motor care is becoming a lost art, as most everything hobby grade is moving to brushless.(thanks to Steve_)

There are many good tips & how to's on this particular site for the DH-9116. There is one in particular that I'd like everyone who plans on modding the Main/Tail Motor to be aware of. I'll state right up front that as I do not have access to the electrical drawings/schematics my determinations is strictly based on user experience.
As most already know the motors on this model don't last very long usually not more than 2-weeks or so with three flights daily.(this has been my experience)
Not long ago I read a post where it was suggested by a user to bypass the MOPS circuit which is a large silicon wire(red) loop. This loop absorbs heat as you fly thus lessening a motor over heat condition. What I don't know for sure but now assume is that this shunt protects Both Motors. The reason for my conclusion is that since shunting this circuit I have gone thru 2 main motors, one stock & one N-60 direct drive motor in like about a week. The new N-60 in just one day! Using an IR Thermometer this tail motor reached 176ºF & that after sitting just several minutes. The resistance of a new unit measures just 1ohm and after the nuclear event 2.6 ohms. The motor is toast & has to be replaced.
As I was replacing it I realized that this bypass may be the reason for the failures so I removed it & now the tail motor gets very warm but nowhere near the 2ndº burn temps it once did. I'm on my last stock motor so I will have to wait to confirm this with the new 180-a motor but I'm confident the brushes will last a great deal longer. The reason for the MOPS Bypass is that there's an assumption that not having it creates the in flight momentary motor cut out however my observation has Not seen that disappear at all so for me this is not the answer to that anomaly. I must say that the new tail motor is such an improvement to how this Heli fly's & I can't wait till I receive the 180-a main motor. This is a toy class heli for sure buts its so much fun to fly.....and that after all is what its all about.

Her is a simple way to lessen the blow of flybar strikes on the canopy. This will not effect the performance of your helicopter.

Originally Posted by robdben

Her is a simple way to lessen the blow of flybar strikes on the canopy. This will not effect the performance of your helicopter.

And here I thought I was the only Krazy one. I've got mine bullhorned & it fly's perfectly.

The simplest way I've found to keep the servo up from sliding up the connecting rod is not really a mod but just a simple swap so that the connecting rod is now on the outside of the servo arm in relation to the mainframe. I believe it also minimizes friction against the canopy and the chances of hanging up against it. There are no bends or angles to hang up, just a straight rod sliding against the canopy.
Don

Thanks so far!

I'll add all the tips to the blog.
Is it OK for you? (name will be added to the pics)
-mike-

Originally Posted by mikefromgermany

Thanks so far!

I'll add all the tips to the blog.
Is it OK for you? (name will be added to the pics)
-mike-

I'm good with it Mike. Do with it as you see fit.

Of all the things I've done so far I think the smartest one is the addition of a Voltage Display/Low Voltage Buzzer. It weights next to nothing & will without a doubt save your batteries if listen to it. This particular one has 2 Super Loud Piezo Buzzers that will get your attention. I personally set mine to 3.70 V which gives me plenty of time to set-r down safely. It will also read each individual cell so when one starts to weaken you'll know right away. I highly recommend it.

This was the best method I could come up with for link issues. It take the slop out and give better geometry. The links and Balls are Tiger Thunder.

Originally Posted by BThirsk

This was the best method I could come up with for link issues. It take the slop out and give better geometry. The links and Balls are Tiger Thunder.

Jesus Christ - how much was the mod?
looks quite solid, though!
-mike-

Originally Posted by ironhorse99

Of all the things I've done so far I think the smartest one is the addition of a Voltage Display/Low Voltage Buzzer. It weights next to nothing & will without a doubt save your batteries if listen to it. This particular one has 2 Super Loud Piezo Buzzers that will get your attention. I personally set mine to 3.70 V which gives me plenty of time to set-r down safely. It will also read each individual cell so when one starts to weaken you'll know right away. I highly recommend it.

This mod has a 2nd benefit too. If your bird gets away and lands in the deep woods or tall grass, you can find it a lot easier with the loud beeper going off. But it is a double-edged sword. The alarm shuts off once the load is removed (flight stops). If you forget to disconnect the buzzer, it WILL WAKE YOU IN THE MIDDLE OF THE NIGHT! Yep, I forgot, but only once, , , so far.
Don

Originally Posted by BThirsk

This was the best method I could come up with for link issues. It take the slop out and give better geometry. The links and Balls are Tiger Thunder.

I did a search for Thunder Tiger and they all seem like much bigger models. Which one uses the connecting rods with ball links that fit the 9116? Thanks,
Don

Overhauled the complete Manual

Also downloadable as PDF here:

Have fun!
-mike-

hello, so im new to all of this but im catching on pretty quick. so far only problem i have is tx , when i want to roll to the right the heli does nothing. can someone tell me what i need to do please. i've read most all the posts on 9116 but have not found a fix. thxs curlyrocks

Originally Posted by curlyrocks

hello, so im new to all of this but im catching on pretty quick. so far only problem i have is tx , when i want to roll to the right the heli does nothing. can someone tell me what i need to do please. i've read most all the posts on 9116 but have not found a fix. thxs curlyrocks

So you cannot bank left/right - Aileron not working?
Was it DOA? Or worked it until now/crash/etc?
Further questions/please ask as written above
here
regards
-mike-