I did a maiden flight on 10/27 after having my new 120 SR RTF for 5 days. Had a few crashes inside my living room but nothing has completely broken thus far. Haven't taken it outside yet and no plans to soon.

This morning, my left (throttle) stick on the TX stopped working unexpectedly. It actually went from intermittently working to not working at all within a 3 minute period. I had the throttle stick in the top most position with no activity. My cyclic control stick works fine and moves everything correctly on the heli (fwd, reverse, left, right).

I rebound the TX with the RX; I changed the throttle trim from one extreme to the other, hearing beeps in the process. I also tried the 2nd OEM battery that was fully and correctly charged. (I had used both batteries with no issue over this 24 hour period.) I even checked over the heli again and nothing was out of place or broken.

Could anything I may have overlooked with the heli cause this?

Also, is it common that the MLP4DSM transmitter stops responding after using it out of the box 24 hrs?

Make sure the main motor didn't come unplugged.

When you bind your controller to the heli always have the throttle in the bottom most position. Also, always have it at the bottom when you plug in the battery to the heli or the esc won't arm. In some cases you also have to make sure the throttle trim is all the way down as well.

Originally Posted by Druss

When you bind your controller to the heli always have the throttle in the bottom most position. Also, always have it at the bottom when you plug in the battery to the heli or the esc won't arm. In some cases you also have to make sure the throttle trim is all the way down as well.

@Druss - I have made sure to do both of these steps but no go.

Originally Posted by Mikey1

Make sure the main motor didn't come unplugged.

@Mikey1 - I have not checked this and will do so today.


If it's not an issue with the main motor, it is the controller? Thanks guys for chiming in.

It'd most likely be the controller if everything is secure. Take it back to the LHS (or where ever you bought it) or call HH, they should fix it free.

It's possible it could be the tx flaking out though kind of doubtful, testing it on another heli/plane may be a good idea.

Ah, one more thing, make your your tx batteries aren't low or dead. The batteries they ship with are garbage..

Originally Posted by sirs69

Ah, one more thing, make your your tx batteries aren't low or dead. The batteries they ship with are garbage..

I wouldn't have thought the batteries in the TX were the issue given that the cyclic (right stick) works perfectly fine. It's only the left stick that's not working.

But, I will check them too!

Originally Posted by Mikey1

Make sure the main motor didn't come unplugged.

Checked the main motor and it seems in tact. All other parts seem to be in tact too, except...

There is a RED wire glued on the 5-in-1 but not connected on the other end.

Where should this RED wire connect to and could this be the issue with no throttle working from the TX?

See attachment.

That would be your antenna. I don't see that wire carrying current for a motor, a light bulb filament at the most.

Originally Posted by Gedexas

That would be your antenna. I don't see that wire carrying current for a motor, a light bulb filament at the most.

Ok, is the antenna fine as-is on the initial pic?

I'm not sure about the wire for the motor current. Does either of the 2 additional pics help to see what you were referring to?

If not, can you post a pic to show me?

Thanks...

Edit: the motor's wires are fine. The "disconnected" wire, looks like 2.4GHz antenna if that's what the heli uses. I think the antenna is a little busted and could be straighter. on my mcpx it's wrapped around a canopy mount, but yours is fine and would not cause a motor malfunction.

So moving throttle makes the heli beep? That's a sign of a working throttle, the motor could be busted too. These motors don't just quit, they die quick, but gradually.

Could you try spinning the motor with your fingers, while slowly advancing throttle? If the motor tries to work, then dies, then it's dead.

Originally Posted by Gedexas

Edit: the motor's wires are fine. The "disconnected" wire, looks like 2.4GHz antenna if that's what the heli uses. I think the antenna is a little busted and could be straighter. on my mcpx it's wrapped around a canopy mount, but yours is fine and would not cause a motor malfunction.

Yes, the 120 SR uses 2.4GHz. Thanks for confirming the antenna is fine.

Originally Posted by Gedexas

So moving throttle makes the heli beep? That's a sign of a working throttle, the motor could be busted too. These motors don't just quit, they die quick, but gradually.

No, moving the throttle does not make the heli beep in any way. What occurred was that unexpectedly, the throttle intermittently worked then just stopped working altogether. It only took a few minutes to go from the throttle working fine, then intermittently, then not working at all. I trimmed it all the way down and retried, trimmed it all the way up and retried. This didn't help.

However, the cyclic works fine on the right stick and it moves everything correctly on the heli.

Originally Posted by Gedexas

Could you try spinning the motor with your fingers, while slowly advancing throttle? If the motor tries to work, then dies, then it's dead.

Sure, I'll give that a shot.

Your heli can have two problems:

1 Throttle potentiometer/ pot wires are broken.
2. The motor is busted.

I can't think of any other problem right now

There is a way to test the motor, so that will narrow it down to transmitter. You will have to connect the motor to a battery directly. You could probably rig a couple AA's if the motor is out of the heli. I don't think you should try a rigged motor inside a heli, it will bite you.

Another way is to simply hit, "reverse channel" on your transmitter's throttle channel a few times, this might make the heli bite you too, and it will probably be broken. That's of course if it starts at all, since it likely has "hot start" protection.

Or, you could try a different transmitter, but I take it's not an option.

You are right, I do not have another TX to test with.

However, I decided to fire everything up about 15 mins ago.

I set the trim all the way down again on the TX before moving the throttle in the up position. Once I moved up, the blades spun. I put the throttle completely down and up again two more times, the blades spun both times.

I haven't made any changes to anything nor performed any additional tests.

Sooo, hmmm...I don't know what to conclude.

I think the transmitter is going out. If you can't return it, you could fix it. It's just much easier to get a replacement, especially if you are not experienced in electronic repairs.

I don't think you should fly the thing until it's working properly.