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Old 08-30-2021, 03:14 PM   #1 (permalink)
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Default FC6250HX support 760μs center pulse??

I just got my FC6250HX unit and I attempted setup by following the video series from Spektrum. I am using an NX10 for my forward programming

I setup the swash plate output and selected 333hz at type, everything works fine on the swash.

When I went to setup tail rotor, I selected 560hz, but there is no place in the forward programming system to tell it the center pulse value of the servo. My tail rotor servo is MKS HBL669, which uses 760μs center pulse.

WHen I plugged the servo in, it worked for a few seconds and then overheated and stopped working. I believe it is damaged now.

My question is this. Does the FC6250HX support servos with 760μs center pulse? Someone told me that the manual says it does, but the person who I was online chatting with at Horizon tech support said it does not.

If the 6250 does support 760μs center pulse, then how do I select that value during setup in forward programming?

All help is appreciated.

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Old 08-30-2021, 03:46 PM   #2 (permalink)
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When I have set 760ms servos on my two 6250s, I only needed to set the frequency of the bus at 560mHz. It automatically changes the servo center to 760ms. I have one with the MKS980 and the other with a BK7006HV. What I have read in the past when getting running a 760 at 1520 is that it will only operate one way and generally travel full direction to one side. I have also read that even plugging a servo in backwards should only cause the servo not to operate. Your situation is not normal from my dealings and from other's experiences. Best I can offer.

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Old 08-30-2021, 04:28 PM   #3 (permalink)
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I agree with Keyrigger and have also spoken to Spektrum about this as well. I initially thought I had issues because my BK tail servo was listed as 333HZ with a 760 center. To get that center pulse you must use the 560 HZ setting in the 6250 and it will pick 760 automatically. BK also indicated to me that their 333 tail should be fine with the high frequency. All is working well with my unit. I also have one set up with the older Outrage Torque tail servos with the same settings and it is working great.

Sorry you are having problems with the setup. Hopefully Brian from Spektrum will chime in and have better info for you.
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Old 08-30-2021, 08:32 PM   #4 (permalink)
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I also have a 760us KST tail servo on 560Hz on my 6250HX

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Old 08-31-2021, 06:26 AM   #5 (permalink)
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Thanks for the feedback. I am not familiar with Brian from Spektrum. I did try to online chat with HH tech support, but that was a frustrating experience. The rep who tried to help clearly did not know much about the 6250, and he terminated the chat when he could not answer my question.

I then tried calling the product support line, and the automated response simply said they had too many calls and that I should call another time - then hung up.

I used to be able to leave my number and get a call back.

I don't know what has happened with HH support, but it's going in the wrong direction.
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Old 08-31-2021, 07:26 AM   #6 (permalink)
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333hz and below uses a 1520us center pulse

560hz uses a 760us center pulse

Do not connect the tail rotor pushrod to the servo until you have verified the operation of the servo and check that the end points are adjusted correctly. Quite a few of the newer servos don't make a lot of noise when they are bound up (aka to much travel) and can overheat rather quickly.

When adjusting the tail rotor end points I always hold the pushrod link onto the servo arm/ball, this just lets you check for jamming without jamming the servo. Once you are sure the settings are correct you can snap the link onto the ball.

Make sure your tail pitch mechanism including the pushrod are nice in free for the best performance. Even something as simple as a tight ball link on the ball can lead to overheating a servo.

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