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Nov 06, 2017, 10:30 AM
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PietenpolAC's Avatar

Need help with mini-vapor rx

I have two new Mini Vapor rx's. Had for some time but just now using. Binding to my DX6i. I mounted a motor connector on one of them. Both have the same issue. Only the servo by the antennae wire operates. The other servo is completely dead, no jitters, nothing. Doesn't matter which stick on the TX is used or in what direction of stick movement. Mode 2. The throttle on the one with the connector operates ok.

I'm not real familiar with my DX6i although I have used it just fine with DT rx's and actuators. I didn't do any special setup after binding. Could I have something set up wrong on the tx side? If possibly a rx issue, what can I do to test or locate the problem? I have a volt-ohm meter, but that is all.

Any insight would be greatly appreciated as I was about to mount one of them in a plane.

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Nov 06, 2017, 11:49 AM
There is a good chance that the servo that's not working is just sticking. This seems to happen on the Mini Vapor receivers (two so far) I've used. If that's the problem, there is a quick, cheap fix, which I learned from ghcrash. Put a few drops of isopropyl alcohol into the servo through the open slot on its top. The servo should then respond to stick movements. Exercise that servo a bit before mounting the rx or putting it away. I hope your problem turns out to be this simple.

Nov 06, 2017, 12:08 PM
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PietenpolAC's Avatar
Thanks for the quick reply, Harvey.

Did your sticking servos make any kind of movement or sound? Mine don't do anything. It is as if they are not receiving any kind of signal at all. I'll try the alcohol as it probably can't hurt anything, or could it?

Nov 06, 2017, 12:36 PM
Smaller flies better...
cybermike's Avatar
Alcohol is fine as long as you give it enough time to evaporate (it gets under the chips). I use gentle warmth from a heat gun at a distance to hasten the process.

If you havenít already, rotate the dead servoís spur gear to make sure it is all freed up. Even a nearly invisible bit of crud in the gears can lock them up.
Nov 06, 2017, 12:50 PM
Bruce, the sticking servos did nothing at all. They seemed completely dead.

Not knowing any better (and not thinking), I tried the servos soon after I dropped in the alcohol, and they worked. But cybermike is the expert; I would take his sensible advice.

Last edited by hdowding; Nov 06, 2017 at 06:15 PM.
Nov 06, 2017, 09:30 PM
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I would do some below check if the servo not working
- Try to spin the gear if it can spin freely ( I would spin it for a while till servo reached the end)
- Check if the gear are meshed correctly
- Check if no broken wire from motor to the board
- Remove the servo and check the brush as well as clean the pad between servo's brush and the board with alcohol or perfume
- Touch the board below servo when powered on if it's hot, if so likely the FET is dead
Nov 07, 2017, 02:54 AM
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PietenpolAC's Avatar
Problem half solved. I looked at the rx's with a magnifier. One motor wire of one of the non-functioning servos was not soldered to the board, just sitting next to the solder. When I touched it to the solder pad, it functioned.

But the other rx seems to have all the solder joints for the non-functioning motor in order. I'll re-solder them just to be sure in any case.

Last edited by PietenpolAC; Nov 07, 2017 at 03:52 AM.
Nov 07, 2017, 02:38 PM
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PietenpolAC's Avatar
They both work now! I'm a happy camper. Thanks to everyone for their suggestions. I tried all of the suggestions and eventually both servos started coming to life until they functioned all the time.

If these RX's hold up they should have more power than my equivalent actuators. A DT RX and two MI .7gram acts weigh about 2 grams. The Mini Vapor brick weighs 2.8 grams. The actuators should be more reliable mechanically since they are just a coil and a magnet, but if these bricks are reliable, I'm willing to give up .8 grams for more authority over the control surfaces. The next(?) step up is the AR6400 brick which is more weight than I like for a slow flying peanut sized plane. I got these for less than $20 each on sale. Wish I could get some more.

Nov 07, 2017, 03:17 PM
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RNAF's Avatar
Hey Bruce, I feel ya. The weight penalty is worth the easy of use and relative robustness. The servo's torque is certainly more than with actuators. The bricks should become available again, as Horizon has released the Vapor Lite HP, which is basically a Mini Vapor with bigger wing span, longer motor and larger battery.

I do clean the servos every few years and I set dual rates to have one or two per cent less throw, just as a precautionary measure to avoid binding.

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