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Old Oct 25, 2012, 06:12 PM
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Daemon's Avatar
Lakewood, Colorado
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And just to clarify. When you got the plane back, you simply re-powered the Tx and the the plane
and then pulled the plug on the Tx to test the failsafe functionality very first thing? You definitely did not
re-set the failsafe positions first?

The problem with "the Rx crashed" idea is that a truly crashed, non-functional Rx won't keep
sending the same PWM frames to the servos and ESC. It'll send nothing, and most
ESCs will shut down. You might test to see what happens if you pull the ESC throttle wire
off the Rx while the motor is running. Does it keep running, or shut down?
The only state I know of where the Rx can keep sending the same thing, is if you do not set
the failsafe positions after a re-bind. Maybe it crashed to that state even with
failsafe positions set, but seems unlikely.

BTW, may want to do a micro power range test and make sure your Tx antenna connector
is not damaged (as has happened to a bunch of us), cutting the range severely.

ian
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Old Oct 25, 2012, 07:14 PM
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thecrawfords67 Just to clairfy you don't use any osd/AP right?
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Old Oct 25, 2012, 07:41 PM
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Originally Posted by picard10th View Post
thecrawfords67 Just to clairfy you don't use any osd/AP right?
Or even a stabilizer. Direct connect between ESC throttle channel and Rx?

ian
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Old Oct 25, 2012, 09:17 PM
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Quote:
Originally Posted by allfiredup View Post
I get very occasional Failsafe glitches showing on my DOSD with the RL rx and DX8. Its just a half second flash of failsafe and happens maybe once every other flight. I never remove my Tx antenna and my reciever antenna connection is taped on so I can't imagine thats come loose.
Is it possible this is just some missed data in the PPM stream? Does anyone else get this?
I've experienced the same thing on more than one occasion, even while flying within LOS. Just as you described, it was a momentary glitch, just long enough for my OSD to announce failsafe engaged and then immediately disengaged. Initially, I wasn't sure what caused it -- Rx antenna orientation, RF interference on the plane, noisy environment, or possibly a loose Tx antenna connector. Now that I've installed the same RL system in a replacement plane, I've noticed it happen a couple of times while working on the bench with a very simple setup, consisting of only RL Rx, speed controller, servos, motor. I rarely remove my Tx antenna, but it seems prudent to check the connector. BTW, I'm flying Turnigy 9x with er9x firmware, ETOSD, and RL.
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Old Oct 26, 2012, 12:03 AM
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With regard to the DX8, it uses an audio style 1/8" plug on the trainer port. Those are
notoriously glitchy if the plug moves even the slightest bit. I used to use one for my mechanical
head tracker's signals, and it was horrible. It looks like the Turnigy 9x uses the same
type of plug, thus probably has the same type of problem.

ian
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Old Oct 26, 2012, 12:11 AM
Power-line attraction pilot
United States, MA, Natick
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Would be great to hear from Sid regarding this inconsistent behavior. About to get mine in the mail... And I am a little worried.
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Old Oct 26, 2012, 12:13 AM
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Quote:
Originally Posted by caall99 View Post
Would be great to hear from Sid regarding this inconsistent behavior. About to get mine in the mail... And I am a little worried.
Which inconsistent behavior are you referring to?
Using audio plugs for the ppm signal is consistently a bad idea..
The other issue with the weird non-failsafe behavior, is the first we've ever heard of such a
problem. A datapoint of one doesn't make a trend.

ian
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Old Oct 26, 2012, 12:17 AM
Power-line attraction pilot
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Sorry should have been more clear. was referring to the glitching failsafe even after Sid improved the sma connector situation. Is it still a trend that the connection is intermittent?
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Old Oct 26, 2012, 12:51 AM
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That's a different problem. So far only one person has reported an issue
with the newer SMA female connector on the Tx. The root cause of that issue is
actually the design of the stock antenna, which is missing part of the male SMA connector
(as is the case on several other brands of antenna) which allows the male connector to
screw down so far that the center pin puts extra stress on the inner female receptacle.

Here's what a normal Male/Female SMA pair looks like

(ignore the thing on the right).

And here's a diagram of the same

Notice there's a cylinder inside the male connector surrounding the center pin (on the left),
that inserts into the white space on the female side (on the right). Those two things
mating together are what normally limit how far you can screw them together. The
center pin does not reach the bottom of the hole (female receptacle) and the only
contact is made on the sides of the pin.

The RL stock antenna, and the very popular long range Nagoya NA-771 antenna
are both completely missing the cylinder on the male side. Instead all they have is
the outer threads and a very long center pin, so the only thing that stops
it from screwing down to the bottom of the threads is the center pin when it reaches the
bottom of the female receptacle. That puts tremendous stress on something that
isn't meant to carry any load at all.
[edit]
Here's a diagram showing the non-standard connector.


[edit]One last diagram, showing how they mate, and why the non-standard setup causes
problems. Again, there are several popular antennas that work this way so it's
not an RL specific problem.


What I'm going to do, is add a hard rubber or plastic spacer around the outside of the female
threads sitting on top of the lock nut which simply limits how far the antenna can be screwed down.

ian
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Last edited by Daemon; Oct 26, 2012 at 04:34 AM.
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Old Oct 26, 2012, 08:38 AM
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United States, CO
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Quote:
Originally Posted by Daemon View Post
With regard to the DX8, it uses an audio style 1/8" plug on the trainer port. Those are
notoriously glitchy if the plug moves even the slightest bit. I used to use one for my mechanical
head tracker's signals, and it was horrible. It looks like the Turnigy 9x uses the same
type of plug, thus probably has the same type of problem.

ian
Good point regarding the audio style adapter. In my case, I've actually hardwired the RL plug into the RF module (I should have mentioned that previously). My RL Tx has the original SMA adapter, so I'm thinking that's a good place for me to start.
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Old Oct 26, 2012, 08:45 AM
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Quote:
Originally Posted by caall99 View Post
Sorry should have been more clear. was referring to the glitching failsafe even after Sid improved the sma connector situation. Is it still a trend that the connection is intermittent?
As Ian indicated, it seems all reported SMA connector issues involve the original style connector (minus one exception). I wasn't very clear in my post, but my RL Tx also has the original style SMA connector.
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Old Oct 26, 2012, 09:38 AM
Chinglish-funny
Joined Mar 2011
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Quote:
Originally Posted by thecrawfords67 View Post
Very strange no one else has had this problem....Sid any comment ?
Hello,if you had try rebind, the FS will reset to zero,that means all outs 0v (do NOT output pulse). So before fly you need to check the fs setting.


Sid
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Old Oct 26, 2012, 10:00 AM
Chinglish-funny
Joined Mar 2011
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allfiredup / wmartin

here shows some reason will cause this(glitch):
1.weak ppm stream (with old tx).
2.fpv gear(Camera Noise,boost dc-dc etc).
3.very nosiy environment(to check this maybe you need a spectrum analysis).
Just try advance binding, maybe it will help to avoid the rf noise.
4.fault tx/rx antenna or fault tx/rx module.


Sid
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Old Oct 26, 2012, 11:25 AM
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When I got the plane back I simply changed the flight pack and tested the controls. Then I unplugged the Rangelink from the Dx8 and saw this activated the failsafe perfectly. I had set the failsafe a week earlier with 0% throttle, and it has never been rebound. When I first got it I performed an advanced bind as per the manual.

I have an OSD but no RTH, so the ESC is connected straight into the Rx. I do use a trainer port for the PPM signal, but it is totally solid and never gets touched in flight. Besides I tried it with another transmitter anyway.
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Old Oct 26, 2012, 12:51 PM
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Quote:
Originally Posted by thecrawfords67 View Post
Besides I tried it with another transmitter anyway.
For whatever it's worth, I wouldn't expect switching transmitters (especially to a different brand)
on the fly would work, as any change in the PPM frame length can really confuse the Rx.
Generally any time the Tx is moved from one Tx to another, the Rx should be rebound.

ian
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