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250 Brushless Motor Losing Power?

Discussion in 'Helicopters' started by Nari, Mar 18, 2019.

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  1. rdsok

    rdsok Well-Known Member

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    An ESC is what controls the speed of the motor whether it's a brushed or brushless.... so it certainly can not be in the transmitter. It's in the heli, it's what the motor is connected to other than the batteries.

    As I've read it, it has been suggested to you that you have two possible causes of the problem... ie the transmitter pot for the throttle being faulty... or the ESC is in need of a calibration. If you've tried a different transmitter, then that only leaves the calibration as your only other thing to try. Unfortunately you've got a toy grade RC heli instead of a good hobby grade one like most everyone else on this board has invested in. This means that they can't tell you how to do the calibration since they don't own the same RC heli, just that is your next step.

    As typical of many low cost devices whether they are toy or hobby grade, it's not the lower quality that is the issue ... instead it is the lack of documentation provided to fully service and maintain them.
     
  2. Tony

    Tony Administrator Staff Member

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    As Randy stated, the ESC is more than likely built in to the board on the helicopter. It's likely an AIO board (All In One) otherwise known as a 4-1 board or a 5-1 board.

    sometimes, the best thing to do with the cheaper models like this is to just replace them with new ones, or upgrade them to something better.
     
  3. murankar

    murankar Moderator Staff Member Armed Forces

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    Those little guys have a single board design. Keeps weight and wording down. Like Tony stated either replace the heli of go with something like a HH Blade product.
     
  4. Nari

    Nari New Member

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    Thanks a lot for your answers.

    Dear rdsok,

    I have found this instructions for calibration. What do you think?

    1.jpg

    V912 TX Calibration

    Just want to describe the calibration of equipment, which was accidentally discovered forum chain tu4kin , with the active support of all branches of the 912 and very brave forum chain Phantom_NGK . Maybe it's someone come in handy. by remlen

    1 - Put the sticks in the middle. (optional)
    2 - Hold the trimmer Rudder left and turn on the equipment. Light up all the lights on the screen.
    3 - Move the sticks in the most extreme situation, first one stick, up and down in the right-left, then the second.
    4 - 1 time press Rudder trimmer to the left

    Calibration completed.


    ==============================

    It would be nice but considering the huge price and availability of spare parts in my area are two deciding factors.
    Other than that, I really enjoy flying V912. I have flown higher grade helicopters too but there is something special about V912 that makes it fun to fly.
    I have another brushless version of V912 that works like a charm but this brushed one had problems since I bought it brand new.
     
  5. rdsok

    rdsok Well-Known Member

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    That looks like how I've heard the gyro getting calibrated and not the ESC throttle... just a wild guess since I don't own one of those. I would certainly save those instructions since it seems these models like you've got aren't well documented and that could be handy as some point... it's just not helpful for the ESC.
     
    Nari likes this.
  6. tntpoof

    tntpoof Member

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    the esc is built in to the all in 1 rx..under the canopy
     
  7. Admiral

    Admiral Well-Known Member

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    If the Pos & Neg wires from the motor are soldered to the PCB you will probably find that it is built into the PCB, in that case you have already changed it.
     
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  8. murankar

    murankar Moderator Staff Member Armed Forces

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    So I just looked at some pictures of the V912 Skydancer. Sorry bro but this kit does not have a 4 in 1. The esc sits on top of the battery. It appears to be located under the electronics try just about the battery. Unless I am looking at the wrong kit I am positive its a separate esc.
     
  9. Tony

    Tony Administrator Staff Member

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    Here is verification that what URI posted is true. Here is an actual picture of a 912 and you can clearly see the ESC mounted on top of the battery. Odd mounting location, but it is what it is. @Nari does your helicopter look like this?

    WLtoys-V912-RC-Helicopter-4.jpg
     
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  10. Nari

    Nari New Member

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    Dear Tony,
    As I said, I have 2 versions of V912: Brushed & Brushless.
    Yes, the brushless version has a separate ESC but the one I'm talking about here is my brushed version which has a throttle problem.

    The brushed V912 doesn't have a separate ESC. This is the picture of my brushed PCB:

    1.jpg
    2.jpg

    Dear Admiral,
    The Pos and Neg wires of the main motor are connected to the PCB through a socket.

    Some days ago, I had a fly with it and it performed well but after 3 minutes, the motor RPM suddenly decreased and helicopter dropped to the ground! I gave it full throttle but it didn't help! I was lucky that at the moment I was flying near the ground (2 meters high). The landing skid is very strong and prevented damage.
    This helicopter flies perfectly well but this throttle problem is very annoying :(
    I wish I could solve the problem somehow.

    I think maybe the main motor is faulty. What do you think?
     
    Last edited: May 29, 2019
  11. murankar

    murankar Moderator Staff Member Armed Forces

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    I redact my statement. I was under the impression that it was the one I found. If your motor is still not getting power orbiting power then its either the control board or the batteries.

    I am going to say TRY new batteries. If it just fell out of the sky after three minutes your lipos are.probably on there way out.
     
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  12. Nari

    Nari New Member

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    I tried different batteries but it has nothing to do with the battery. My other helicopter flied perfectly with the very battery that caused my brushed V912 to drop from the sky.

    Today I tested my brushed V912 with my Brushless TX. I didn't feel any noticeable improvement in throttle input behavior.
    It is extremely strange to me! It is either related to the PCB or the motor. Nothing else could cause this problem, could it?
    It should not be that much complicated.

    The previous PCB and the new red PCB (above picture), both behaved similarly and the problem is still there.
     
    Last edited: May 29, 2019
  13. rdsok

    rdsok Well-Known Member

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    Make certain that you are testing with new batteries with the same or higher capacity and amperage output... just using a different one that is also used doesn't help.

    Changing the PCB was a good test but you still have to find out how to calibrate them also. Calibrating them then lets the ESC know where the throttle endpoints for the motor being used are at and these can vary even with the same make/model.
     
  14. Tony

    Tony Administrator Staff Member

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    Well, you have narrowed it down to one of two things. The board, or the motor. I would think the motor is cheaper, and seeing as it is brushed (missed that, or forgot earlier, sorry) it can and does wear out. It may just be its time.
     
  15. Nari

    Nari New Member

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    Yes, some of them were new batteries.

    How should I calibrate them properly? Is there a general rule for throttle calibration that applies for most (almost all) makes and models?

    I have decided to replace the motor as well but it is certainly not worn out because this helicopter has seen no more than 9 flights and I cool the motor down with my home-made fan immediately after each flight.

    ==============================================

    Some hours ago, I noticed something strange while testing my brushed V912 with two different TXs (Brushed TX and Brushless TX).
    In fact the TX for both models are exactly the same but I noticed different behavior. Let me explain:

    First of all, I tested my Brushed V912 with my Brushless TX and the result was that even with slightest amount of throttle input both main and tail motors started spinning.

    After that I tested my Brushed V912 with its own TX and the result was that with a slight amount of throttle input only tail motor started spinning and the main motor didn't respond at all until I increased throttle a little more and then it started spinning too!

    And the final test! I tested my Brushless V912 with Brushed TX and it performed perfectly and with the slightest amount of throttle input both motors started spinning.

    The more I test and discover, the more I get confused! I'm really at my wits' end! :help:
     
    Last edited: May 29, 2019
  16. Tony

    Tony Administrator Staff Member

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    good luck and hope you get it figured out. I don't seem to be much help in this one so I'm bowing out.
     
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  17. rdsok

    rdsok Well-Known Member

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    There really isn't a standard method for setting throttle end points for an ESC but there is a more common one... only it's unknown if it works on your or not ( that is why Tony was asking about a label earlier )....

    You can try this but there is no promises made...

    Remove the main rotor and tail blades ( safety precaution )
    Turn on your transmitter and move the throttle all the way up to high
    Plug in the battery on the helicopter... if you hear a beep or series of beeps... lower the throttle to the lowest point. If you don't hear the beeps after just a bit... go ahead and set the throttle back to low on the transmitter anyway.

    Unplug the battery, turn off the transmitter and put the blades back on.

    If that doesn't work... all we can suggest is to search the internet further. You did find the other calibration settings that some models use for the gyro... hopefully you'll find one for the ESC also.


    Good luck... I'm also out of other ideas to suggest
     
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  18. Admiral

    Admiral Well-Known Member

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    May or may not be relevant, but years ago I had a similar problem with a Blade MSR or 120SR where a faulty tail motor was causing similar main motor issues, worth a look if you have a spare tail motor or just unplug the tail motor & hold the helicopter to see if the problem is still there.
     
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  19. murankar

    murankar Moderator Staff Member Armed Forces

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    The raising and lowering of the throttle stick is the most common way to calibrate throttle end points. Give it a shot.
     
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  20. Nari

    Nari New Member

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    Thanks a million for your suggestions my dear friends!
    I'll try all of them and let you know if I notice anything worth mentioning.
     
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