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Mikado Modellhubschrauber . GrandRC . CanoMod

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Radio - JR & Spektrum DSM > DX7 and Lockouts
 
 
petesmith
Heliman
Location: Milwaukee, WI

Last weekend my friend was flying his Bergen with his two week old DX7. After 10 minutes into flight, when he had it doing a roll, the heli went into the ground. We ran the 50 yards to get to it and found it was totally locked out - no response from cyclic, yaw, or throttle. The engine was at idle and the light on the receivers were on. Absolutely no response to the sticks at all. After cycling power it was fine.....

Horizon will not cover "collateral damage" to the heli ( ~ $400 in parts plus a custom painted canopy ), let alone the shipping to the service shop :<

Anyone else experiencing lockouts? That was why he bought the radio - to not get them!!!!!!!
04-25-2007 Over year old.
HOMEPAGE  
 
 
tomdavey
Heliman
Location: Rhode Island

Well, that's disturbing. Like you said, it's the whole reason to go DSM. Hope it's just an isolated incident but it is scary. Let's see if others have similar stories.

Raptor 50v2 - TRex 450SA - Futaba 9CHPS
04-25-2007 Over year old.
 
 
RCHeliJim
Elite Veteran
Location: Orem, UT USA

Also, what are all the details on the installation, environment, range check, RX power, etc..... ? In the end it could be a faulty RX or TX, but could also be something else. The Spektrum technology works as advertised - but there are going to be faulty units for sure Too bad to hear about the crash.



Go Fly, Have Fun!!
-Team Quick UK
-Team RCHeliMag
04-25-2007 Over year old.
HOMEPAGE  
 
 
bmw
Senior Heliman
Location: Lake Zurich U.S.A.

I have seen on some other post the same thing!

Runway? what runway??
04-25-2007 Over year old.
HOMEPAGE  
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

We won't really know what or where the potential problems are until and unless Spektrum opens up their code for inspection.

But they're not talking . . . . . . or helping.
04-25-2007 Over year old.
HOMEPAGE  
 
 
JuanRodriguez
Elite Veteran
Location: Rochester, New York

Quote 
We won't really know what or where the potential problems are until and unless Spektrum opens up their code for inspection.

And so we will never know.....
04-25-2007 Over year old.
 
 
petesmith
Heliman
Location: Milwaukee, WI

Lockout

A full range check was done immediately before the flight. He walked 30 to 40 paces away...

Another post mentioned that having the Transmitter turned-on too close to the receiver can cause problems, but it was 1 to 2 feet away.
04-25-2007 Over year old.
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joeycoates
Senior Heliman
Location: Dallas, Texas

I do not have a DX-7, but I read a post about how Spektrum is now selling a small capacitor that has a plug on it to put in an unused channel on the reciever. Evidently if the reciever drops under 3.8v it goes into a reboot mode that causes an aileron hardover. The capacitor will keep things above 3.8v during a high draw period so that it does not reboot in flight.
04-25-2007 Over year old.
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

Interesting, the initial lack of a capacitor to help against low voltage below 3.8V I would not consider a design fault. It's up to the user to provide adequate voltage.

But waking up (booting) with a hard over on a servo signal other than throttle definitely is a design fault.

And after rebooting, not being able to re-acquire the signal, even when you walk right up to it with the transmitter, well . . . . .
04-25-2007 Over year old.
HOMEPAGE  
 
 
RCHeliJim
Elite Veteran
Location: Orem, UT USA

Quote 
But waking up (booting) with a hard over on a servo signal other than throttle definitely is a design fault.

The AR7000 does not do this (some of the 6100s do and there is a fix for it now) - I have tested it dozens of times with 4 or 5 of the 7000 receivers. The reason some people get the hard over on reboot with a 7000 is because they are not rebinding the receiver with everything set at neutral. On reboot the receiver goes to the bound position on the servos. I have tried this test many times with different bound positions and that is what it does. I can cycle my AR7000 receivers as much as I want and the servos do not do the "hard over" thing. This doesnt happen when I cycle the TX either.

Like I said, I bet this crash boils down to a defective unit (rx or tx - check the receiver wires also) or another source. The DX7 with the 7000 has proven pretty darn solid overall (over 100 flights myself without an issue in various environments/aircraft).



Go Fly, Have Fun!!
-Team Quick UK
-Team RCHeliMag
04-25-2007 Over year old.
HOMEPAGE  
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

Is this booting with the servo positions at time of binding documented in the DX7 manual or specs. ?

And this failure to re-acquire the signal is still a problem.
04-25-2007 Over year old.
HOMEPAGE  
 
 
RCHeliJim
Elite Veteran
Location: Orem, UT USA

Quote 
Is this booting with the servo positions at time of binding documented in the DX7 manual or specs. ?

I do not know, I will have to look - but I do know that is how it works as I can set the servos at random positiona during bind and they will return to those places during boot.

Quote 
And this failure to re-acquire the signal is still a problem.

This is not the normal behaviour either, like I said - I think this person probably has a faulty rx or tx. The normal behavior that I have found through dozens of tests on this is if I cycle the RXit will regain signal from the transmitter almost instantly - every time. BUT, if you cycle the TX, then there is a second or two before full control is found. Honestly, as long as I leave the transmitter on the rx will connect as fast as I can apply power to it... at least this has been the case for mine.



Go Fly, Have Fun!!
-Team Quick UK
-Team RCHeliMag
04-25-2007 Over year old.
HOMEPAGE  
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

May have to do some experimenting with coming out of a low voltage condition on the RX ( < 3.8V ) to see what happens.

Where do the servos go when the RX is turned on without the TX ?

Since Spektrum is not talking, we have to find out the hard way.
04-25-2007 Over year old.
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air365
Heliman
Location: Long Beach/ CA

the manual said u need to rebind the rx after set up the tx with heli (sub trim, travel adjust....) I never had any lock out problem with dx 7 thru. about the voltahe protect. you can buy the cap. from radioshark or electric store. it 10v/4700uH. it is around $1.
04-25-2007 Over year old.
 
 
RCHeliJim
Elite Veteran
Location: Orem, UT USA

Quote 
Where do the servos go when the RX is turned on without the TX ?

I answered this one above I think - they go to the bound position. Wherever the servos were at during binding is where they go when the RX is booted without a TX signal. This is the behavior I have noted during my time with the system so far....



Go Fly, Have Fun!!
-Team Quick UK
-Team RCHeliMag
04-25-2007 Over year old.
HOMEPAGE  
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

Spektrum is clearly more interested in marketing than the technicals.

The current consumption for the 7000 RX I can not find.

Assuming 100ma draw for the 7000, that 4700uf capacitor will give only about 100ms hold up time for the RX during low voltage conditions.

IF the external voltage drop doesn't also drain the capacitor.
- - - - which, of course, it will, so, what good is it ?
04-25-2007 Over year old.
HOMEPAGE  
 
 
xfixedwing
Senior Heliman
Location: Miami, Fl

I had an experience with my DX-7 with low voltage (due to a bad switch harness) the servos do not go to the same positions on reboot as they do when there is a lock out.. At least with mine with lose of tx signal my servo move to the position at time of binding..low throttle, neutral cyclic... But with low voltage and a reboot my throttle and cyclic remain the same positions and pitch servo will go negative pitch( I think they return to the position they were when the tx and rx last communicated).. Try this on your heli.. Just turn the tx off to test a tx loss of signal.. then just turn the rx power on and off without turning off the tx see what happens...

hybrid heli and matching PRIUS!!
04-25-2007 Over year old.
 
 
andres.c
Key Veteran
Location: Florida , Dade County 33173

http://grandrc.com/inc/sdetail/70408



Details:
For DSM system
Prevents voltage drops to receiver
Plugs into any open channel slot

Overview
Spektrum's new Voltage Protector prevents a DSM? receiver's voltage from dropping below the proper operating level in lower voltage applications such as 4-cell 1/12 carpet racers. Installation is as simple as plugging it into an open channel slot on the receiver unit.

this unit is suppost to prevent low voltage condition
04-25-2007 Over year old.
 
 
Wyn
Senior Heliman
Location: Oregon, USA

Quote 
IF the external voltage drop doesn't also drain the capacitor.
- - - - which, of course, it will, so, what good is it ?

I agree. At 3.8 volts and say 4 amps, that cap is essentially across a resistance of about 1 ohm (0.95).

Don't have a DX7, but thought I read that the failsafe is hold last position on everything but the throttle, which can be set to idle. So re-boot and failsafe are not going to be the same since there isn't a "last position" yet on re-boot.

Wyn
VoltMagic
04-25-2007 Over year old.
 
 
AirWolfRC
rrProfessor
Location: 42½ N, 83½ W

Quote 
Prevents voltage drops to receiver
Plugs into any open channel slot
And if you believe that, I've got a bridge in NY . . . . . . . . .
04-25-2007 Over year old.
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Radio - JR & Spektrum DSM > DX7 and Lockouts
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