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Old Oct 27, 2006, 08:46 PM
Where is the lift?
cptsnoopy's Avatar
USA, AZ, Phoenix
Joined Nov 2005
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AR-6000 turned off inflight (orange light went out)

I lost my eRaptor today while using a spectrum system. (the transmitter is the JR6102 with the spectrum DX-6 rf section inside. the switching voltage regulator mod is installed also) I have not had any problems prior to this accident. I flew for approx 5 to 6 minutes of normal loops-rolls-inverted and was hovering approximately 30 feet away and about 20 feet high tail in (best angle for antenna) and the radio stopped cold. The motor quit and there was no reaction from the servos all the way to the ground. The helicoptor was destroyed as you could imagine. I looked at the AR-6000 and the bind light was off. I tried moving the servos with the Tx but no response. I unplugged the AR-6000 and plugged it back in and the bind light came on and stayed on. I moved the sticks on the Tx and the servos moved normally. This was the same as having a long term lockout. From the looks of it, it was never going to rebind until the power was removed from the receiver. I thought I had read about this sort of thing happining before but I don't really recall the details. I have flown this heli with this system for over 30 flights with no troubles until now. If any others have had similar problems with the spectrum please post so I can get a better idea of what is going on. I was so impressed with the spectrum system I already have a DX-7 on preorder.
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Old Oct 27, 2006, 10:04 PM
VE7FM
TheSteve's Avatar
Canada, BC, Langley
Joined Nov 2004
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Just a guess but the receiver may have locked up due to static. I have also read other reports of receivers going to "sleep" until power cycled.
The Spektrum ground systems certainly have had static problems, but the newer
"Pro" systems seem to have solved most of the issues.
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Old Oct 28, 2006, 07:18 AM
slow but inefficient
Ron Williams's Avatar
Riverhead NY USA
Joined Dec 2000
3,097 Posts
My bet would be on ESC problems; overheating is the worst culprit.
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Old Oct 28, 2006, 11:39 AM
Got shenpa?
flieslikeabeagle's Avatar
Los Angeles
Joined May 2004
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Cptsnoopy, sorry to hear you lost your helicopter. I lost a nice balsa parkflyer to the same kind of problem this summer.

Certainly BEC overheating can cause similar symtoms, however, myself and three other RC pilots I know have all experienced Spektrum lockouts that did NOT involve the BEC. Two happened at Brookhurst Park in Pasadena, CA, a site with unusually high RF interference (it even affects top of the line PCM systems on 72 MHz). The third happened onstage in another high RF environment, the inside of a sound stage at a local television production companies facilities.

In each case, the receiver locked up solid, and stayed locked up until battery power was removed and reconnected. In each case, the BEC was cool. In each case, full control was restored as soon as the power was cycled.

I lost my Hotpoint EP (balsa built up parkflyer-sized pattern ship) at Brookhurst Park. One of my friends lost his Slow Stick at the same location, no big financial loss, but it headed towards people in the parking lot after the Spektrum locked up, and that could have led to something much worse. The other friend was controlling a robot (on the ground, in the television facility) with it when his Spektrum locked up, so there was no financial loss, but he had to scramble to fix the radio and repackage an inflating dummy doll that the transmitter was supposed to trigger as a stage gimmick - when the Spektrum locked up, it went to failsafe, and that triggered the inflation of the dummy.

I am curious whether the newly announced DX-7 and companion receivers will fix this lockup problem or not. It's bad enough losing a $300 or $500 parkflyer/helicopter - but the giant-scale guys will not be happy if a Spektrum lockup causes the loss of a $10000 1/3-scale plane.

In fairness, I have had hundreds of successful flights with the DX-6 at the same location, and only two bad ones. (One the lockup, the other a receiver that died early in it's lifetime, and never came back to life - defective manufacturing).

-Flieslikeabeagle
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Old Oct 28, 2006, 11:48 AM
Where is the lift?
cptsnoopy's Avatar
USA, AZ, Phoenix
Joined Nov 2005
6,318 Posts
Quote:
Originally Posted by Ron Williams
My bet would be on ESC problems; overheating is the worst culprit.
I am sorry that I did not give enough info. The receiver was powered by a relatively new (approx 4 months old) 5cell 1500mah NiMH receiver battery. I have not touched it since yesterday but I am going to test it if I am able.

Keep in mind that I unplugged the battery after getting no response from Tx stick movement (orange light out on the Rx) and after plugging it back in a few seconds later, the bind light came back on and stayed on plus I could move the servos normally. So, unless there is a problem with the battery (I will vibrate it while testing it to check for an intermittent open) the receiver became unbound while flying for some other reason.
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Old Oct 28, 2006, 11:56 AM
Where is the lift?
cptsnoopy's Avatar
USA, AZ, Phoenix
Joined Nov 2005
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Thanks for the info flieslikeabeagl, I thought I had read about this happening before. I too am hoping the DX-7 system does not have this issue. I don't mind loosing an inexpensive model but I can't afford to loose my heli more than once every couple of years. (that is asking a lot I know but at least I was on track as this one lasted one year with no repairs ever being made to it other than upgrades and replacing one worn part.)
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Old Oct 28, 2006, 01:17 PM
Where is the lift?
cptsnoopy's Avatar
USA, AZ, Phoenix
Joined Nov 2005
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the receiver battery checked out ok. just a rare problem with the AR-6000 it would appear.
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Old Oct 28, 2006, 01:30 PM
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Denver, CO.
Joined Feb 2006
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I think you should check your complete onboard system for anything that may cause a voltage drop coming out of the ESC to the receiver. If the battery voltage goes down below the cutoff value, the receiver will lock-up and the supply voltage will have to come up over the that minimum level before the receiver will operate. It may even have to be rebooted.(turned off and back on) I have also been told that pulling the throttle back to idle will do the same thing.

I am a safety officer at the field where I fly and there have some concerns raised about some of the loses we have had with Spektrum controlled aircraft. Yesterday, I spent the afternoon with a fellow hobbist and ET discussing set-up and testing of the complete on-board system of EP aircraft. They have over 20 EP aircraft of various sizes all on Spektrum with no problems. Please, he emphasizes the testing of all the on-board equuipment.

I currently fly 9 fuel planes on the Spektrum and I am really interested in the minimun cutoff voltage as well. I am using some 4.8 volt batteries and I am beginning to wonder if I need to go to all 6 volt batteries.

I am looking for the cut-off voltages of both Spektrum and other brands of 72 meg receivers.
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Old Oct 28, 2006, 01:44 PM
Where is the lift?
cptsnoopy's Avatar
USA, AZ, Phoenix
Joined Nov 2005
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Hi TomLee,

This setup was using a receiver battery. I just finished testing it. I charged it Yesterday before flying and I always check my batteries just prior to flight. The receiver battery was 6.68volts IIRC. After the receiver failure yesterday I let the battery sit all night and today I put a 1amp load on it and it held 6.0volts for some time before starting down. after 20 minutes it was approx 5.6 volts. after I cycle it 3 times I will attempt to take a picture of the performance graph to illustrate the results. I subjected the battery to vibration while discharging and found no intermittant open due to vibration. I am very confident that the battery was not the issue. There was no on/off switch in the system, the power lead from the battery was plugged directly into the receiver.

Thank you for your input.
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Old Oct 28, 2006, 01:57 PM
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My people told me to be sure to check the entire system as one unit.
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Old Oct 28, 2006, 02:05 PM
Where is the lift?
cptsnoopy's Avatar
USA, AZ, Phoenix
Joined Nov 2005
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that is a great idea but it is a little late now. There was significant damage to at least one servo and I don't know the condition of the rest.
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Old Oct 28, 2006, 02:47 PM
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flieslikeabeagle's Avatar
Los Angeles
Joined May 2004
10,940 Posts
Quote:
Originally Posted by TomLee
I think you should check your complete onboard system for anything that may cause a voltage drop coming out of the ESC to the receiver. If the battery voltage goes down below the cutoff value, the receiver will lock-up and the supply voltage will have to come up over the that minimum level before the receiver will operate. It may even have to be rebooted.(turned off and back on) I have also been told that pulling the throttle back to idle will do the same thing.
Tom, when I experienced the lockout, it was in a model that already had dozens of flights on it. All the equipment was solid, in good condition, and quite flightworthy. I took off and started the flight normally, only to lose all radio contact with the model a minute or so into the flight, while flying in a straight line at part throttle, a situation which puts very little stress on the ESC, the BEC, or the battery.

The plane (Hotpoint EP) was a well trimmed model at some altitude, so I had many seconds in which to try to regain control. I did try zeroing the throttle and bringing it back up, with no results. None of the controls responded, right up till the plane went into the ground and smashed into pieces.

After the crash, I ran over to the site, and immediately put my finger on the BEC in the ESC; it was at body temperature, not hot at all. The battery had been thrown a few feet in one direction, the motor in another, and so on, but I collected all the scrap together and plugged all the electronics back together. As soon as I reconnected the battery, everything came back to life and all servos and ESC/motor worked, except that one servo had stripped gear teeth, and the motor shaft had bent from the impact so the motor wobbled.

When my friend experienced a Spektrum lockout on the ground (in the TV studio), he had the same sort of experience: nothing was wrong with the electricals, but the receiver had locked-up and would not recover until the battery was removed and reconnected.

I am pretty sure that all three of the incidents I reported (my own, and my two friends) DID NOT involve voltage to the Rx dropping too low. Rather, it seems that in each case, the AR6000 receiver locked up after being exposed to strong levels of RF radiation in the vicinity.

If you've ever experienced the "blue screen of death" while running Windows 95 or 98, you already know that it is quite possible to put a microprocessor into a locked-up, "stupid" state from which nothing but a reboot will enable recovery. All it takes is a line or two of defective code in the software running on the microprocessor - in my example, the poorly coded Win9X operating systems.

Well, the AR6000 also has a microcontroller in it, and also runs software, and therefore a software bug could cause the same sort of lock-up. My (unconfirmed) suspicion is that this is exactly what is happening.

As to the RF interference, Mount Wilson (with megawatts of 72 MHz FM, and TV stations) is line-of-sight and not too far from Brookhurst park. JPL, and any high-powered RF they might use, is a few miles away as the crow flies. My handheld Wi-Fi detector lights up like a christmas tree when I turn it on at this park. And I have seen heavy RF hits, glitches, and dropouts on every Rx/Tx combo used at this field, from cheap 27 MHz toys to cheap 72 MHz single-conversion setups to sophisticated dual-conversion 72 MHz setups to even more pricey 9-channel 72MHz PCM setups (Futaba 9 in PCM mode).

I think the Spektrum equipment is very, very good, but I suspect it does not cope gracefully in conditions of very strong RF interference.

-Flieslikeabeagle
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Old Oct 28, 2006, 11:52 PM
'FPV'er...not a "LOS'er
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Las Vegas, NV
Joined Sep 2003
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It is good to hear of some problems with the Spektrum...not meaning I'm glad there have been problems, but glad some information is out to keep an eye on.

It almost sounds like some folks think the Spektrum is supposed to be error-proof. Anything can and will fail to include high end PCM, low end FM (and AM), Spektrum DX6, Spektrum DX7, etc.

The only problem I've had with my Spektrum was on a Kevlar, CF reinforced F5D plane where I taped the AR6000 antennas against the fuse...almost lost the plane on that one. Once I untaped the antennas and just let them hang outside the fuse like whiskers the range problem went away. I've had way more problems on 72Mhz and I think the 2.4G technology is a great step in making our systems even better. I can't wait to convert my Evo to 2.4G when systems come out that work and allow for more than just 6 channels.
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Old Oct 29, 2006, 11:49 AM
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flieslikeabeagle's Avatar
Los Angeles
Joined May 2004
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Vantasstic, on another thread a Spektrum user reports having been able to get his AR6000 to go into lock-up by momentarily lowering the supply voltage; once locked up, the receiver sometimes would recover after a few seconds, but sometimes would not recover at all until the power was cycled.

Microcontrollers bring new capabilities to our inflight electronic systems, but unfortunately, also bring new failure modes that did not plague our old all-analog electronics systems.

I'm still a happy Spektrum user. As Vantasstic says, anything can and will fail.

-Flieslikeabeagle
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Old Oct 29, 2006, 03:49 PM
'FPV'er...not a "LOS'er
Vantasstic's Avatar
Las Vegas, NV
Joined Sep 2003
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Thought I might have seen my first DX6 failure today. A fellow flier was burning some serious holes in the sky with his NES WILD on 4S, with MPX 480-4 BL, ~4.7x4.7 prop, and a Medusa research 2A (I think) BEC. After a couple of mach speed passes his throttle pulsed and he immediately chopped power. After that he (we) thought we saw a small puff of smoke come out of the plane and his Wild gracefully arced up slightly and then down into the desert with no radio response.

Upon returning with the carnage there was no blatent signs of where the 'puff' came from or what part failed. I did notice with powered applied his AR6000 did nothing...no light, no ESC beep, nada. He pulled the Medusa BEC out of the system and reconnected the ESC with (now) enabled BEC and everything came back to life. I felt bad he lost his plane, but felt good it wasn't anything from the Spektrum system...just a separate BEC that took a dump at the wrong time.
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