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Old Jan 04, 2015, 02:51 AM
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Failsafe power issue <was: lost confidence in XPS>

I lost another 80" Sparrowhawk today, last week I lost a 80" zero both totally destroyed.
Same thing happened I lost all link with the planes , today I had 10 sec of waving the transmitter in all directions but nothing, it just stayed on its course towards the ground. Is it possible to be swamped on 2.4gig by mobile phone towers? A new one has just gone up about 1 mile away.
Don't know what to do now I don,t want to risk any more planes.
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Last edited by JimDrew; Feb 05, 2015 at 01:45 AM. Reason: Customer concluded that failsafe did not engage which is only possible due to complete loss of power
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Old Jan 04, 2015, 07:10 AM
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Check that the centre pin in the aerial base, that the antenna screws onto , is still proud of its surround, It's been known to get pushed in and not make reliable contact..

I've never had a problem with my XPS stuff , used it since the day the MAAA wankers decided it was OK for Aus .....
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Old Jan 04, 2015, 11:46 AM
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Did you perform a range check prior to any of these flights?

Do check the center pin on the transmitter module. If you have an old version of the transmitter module and if the antenna is ever partially cross threaded, that can push down the center pin and break. We changed the design in late 2008 to no longer use those types of connectors and that stopped the possibility from occurring.

Does the 2.4GHz antenna feel loose, and turns easily? If so (especially if the plastic case is cracked) then the coax could be broken internally from repeatedly bending.

What transmitter are you using? If you are using a Futaba 9C, these are notorious for having bad module pin solder joints. I have never had a report of a Hitec with this issue, and only one case of a JR9303 having this issue.

Which receiver are you using? How are you powering the setup? Are you using a switch between the battery and receiver?

Cell phone towers will not create a problem. A Nexrad radar (ball) that close would not even let you connect the system though... that is 750,000 watts of power on 2.7GHz and the bleed over is so severe that no 2.4GHz device can operate properly within a mile, and it is recommended to be at least 7 miles away to eliminate any possibility of a frequency issue.
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Old Jan 05, 2015, 12:01 AM
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I had a situation today I thought id never see a deans connector fully plugged in and no power to the receiver I'm a mechanic and deal with connection issues in all types of situations and so I pulled my volt meter out and verified what I was expierencing good battery good solder joints on both sides the loss of power was in the flat tab that faced the other tab in the connector - the surfaces were clean and undamaged by spark issues it was only a 3 cell lipo but if I just twisted the deans connector a bit power would magically come back to the receiver the blinking light on the receiver was the tale tell that informed me before I flew the 2 nd flight of my mini Katana this plane moves at close to 100mph and I almost lost it had I not noticed before putting on the canopy that the receiver was blinking and I too could of lost a plane today guys what I did to resolve the problem was to take a pair of pliers and slightly twist both flat tabs so as to make them tight at the Conection point hope this helps anyone else out there and one thing I did notice prior to the issue was that my connectors were pluging in and out easily not realizing this was a sure sign of trouble so twist those deans or don't use em guys if it can happen to me it sure can happen to someone else !!!!!!
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Old Jan 05, 2015, 12:26 AM
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Ps I will be phasing out all my deans to something else at this point I don't trust them anymore
I too could of had a plane shut off in mid flight and plow into the ground because of this issue
Or worst someone gets hurt !!!!
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Old Jan 05, 2015, 01:15 AM
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This is actually quite common with Deans Ultra plugs and other types of "T-plugs". I have seen this many times myself. Back in the early R/C car days we use to use Deans plugs, but quickly learned that these problems can occur in the middle of a race - that is why you saw racers soldering battery packs directly to the speed controllers for every race.

I only use bullet type connectors for my setups.
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Old Jan 05, 2015, 03:04 AM
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The Zero was lost with a MX22 and I blamed that and went back to my trusty JR10X.
Both planes had 2s lipos with regulator and the early 10 channel receiver, on hopping esti.
The regulator switch when closed turns it off so power is always on and circuit complete when switch is open so I don't think that was a problem. Both planes had an opto switch for the ignition module the same one as I took the one from the Zero and put it in the Sparrowhawk. I initially thought that this could be the problem as it was common to both crashes, but I am not convinced. After reading "jackmobile" post about deans, I thought "bugger" I use deans plugs and the same 2 receiver packs would be at least 5 years and those female plugs would have had a lot of use. I have often looked at the surface area of those plugs and would never have suspected them. I really hope that is the culprit as I have never had a problem with my 10X and XPS.
I have changed the TX module in my 10x hoping that was faulty, center pins on both are level and I never remove the Ariel or move it as not to fatigue the centre wire so I am confident about the connection there. When the Zero went in it was the third flight for the day and the Sparrowhawk had been up 4 times that day before the crash. Those deans look bullet proof I would not have suspected them.
What type of plug do you suggest I change to and how long do they last before the are unreliable. Should I check the pins in my transmitters they both could,t be faulty? Thanks for the help and advice.
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Old Jan 05, 2015, 04:05 AM
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Can you check again the TX modules aerial socket ? you say it's " level" but the wire should protrude about 3 mm from the white base , and be about level with the "gold" thread ...

I got rid of Deans ( and clones) ages ago , use XT60's on Rx packs now.... EC3's are popular here too ...
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Old Jan 05, 2015, 04:58 AM
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See attached photos

Here are the connectors of both modules
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Old Jan 05, 2015, 06:48 AM
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Those pins look fine to me...

Quote:
Originally Posted by cellbuster View Post
Here are the connectors of both modules
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Old Jan 05, 2015, 07:09 AM
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Jim please post this info about deans somewhere where everybody can read and tell all of their friends about this my money is on the deans connector being the culprit , I have been flying 13 years and never would of given it a second thought if it hadn't happen to me !!!!

anybody interested in a couple dozen deans most new and some slightly used going cheap
I have bullet connectors in the box never going back to deans again !!!
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Old Jan 05, 2015, 02:25 PM
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That center pin looks fine. How did you setup your failsafes? That would really tell us if you had a complete loss of power or not. If the plane went into failsafe mode, that is an RF related issue. If it just stopped responding and didn't enter failsafe mode, you know for 100% sure the issue is power related. Were these gas/glow or electric powered?

"Both planes had 2s lipos with regulator " - ugh, that is the last thing I would recommend using in any aircraft. Regulators have a potential for failure and the switching type often times will latch up when powering on when there is insufficient current, resulting in it never turning on.

You didn't answer my question about the range tests prior to any of these flights. Have you done a range test with that transmitter module and receiver since these crashes?

I noticed that you stated you were on your 3rd and 4th flights when the crashes occurred. Did you check your Lipo battery voltages?
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Old Jan 06, 2015, 01:34 AM
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Jim
Both planes were petrol 2 stroke engines.
I had failsafe setup on throttle to go back to idle, the rest were hold.
The Zero went in too quick to tell if the throttle closed, but the Sparrowhawk was close and I had 6 terrifying seconds of manipulating the tx to get back control.
The fail safe was set to 2 sec and it went in at full throttle so it says that there was no power. I have 3 small models with with regulators and JXT plugs and have had no issues so in hind sight it fits with loss of power.
I have not done a range test since the crashes with the receivers but tested both setups originally with the motors running and a helper rotating it through 360 with the button pushed at 50 paces. I think I will go away from regs and back to a battery pack. Do you recommend any type of connectors and cells in lieu of the lipo and reg.
Both tx modules were sent back for 3.1 upgrade and all my receivers about 12 in total, some I bought from other club members who now use other systems.
The receivers were foam rubber wrapped and suffered no external damage, would you retire these or if they check out in a range test will they be ok to use.
again,
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Old Jan 06, 2015, 01:45 AM
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Voltages were fine as reg has led indicator and lipo pack was 2s 2700 mah I still had 2 green on reg.
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Old Jan 06, 2015, 07:35 AM
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Ec3 , EC5 and XT 60 and XT 90 are my new bullet connectors of choice till I find an issue with them put my order in yesterday sorry to hear about your planes cell buster after discussing this issue with a few flyers and comparing notes we believe those pesky deans were also the source of a few mishaps at our field except for when some choose to still fly dsm2 stuff those get hits at our field often
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