Liqi

I would like to start a semi official thread.

About 2 weeks ago, a friend and I were out flying and on his first flight of the day with a composite arf 2.6M Extra. He was making a half throttle straight and level pass, the plane then went full nose down straight into the ground, with no lock out (his lock out is set for throttle idle.) It destroyed the plane.
The DX7 and the AR9000 were both sent back to horizon and check out okay. I continued to fly my Trex helicopter the rest of the day on a futaba 2.4ghz 14MZ with no problems.

Yesterday the same friend(who owns our local hobby store) and I were test flying a brand new bind and fly Park Zone Habu for one of his customers with a DX5. I took off on the second flight and it did a roll all on its own, I lowered the throttle a little, and it then went off on its own pitching up and rolling again crashing moments later.

A range check was done on both models.

I am a Futaba guy, but I don't push it on to people. My friend and I both recommend the Spectrum radios many people not interested in spending more on a Futaba or JR. Most of his customers purchase Spectrum equipment. I know JR and Spectrum are the same but all these problems are a beginning for concern for us.

Has anyone else had similar problems?

jaka

Hi!
No!
Did you check the servos?

Free Bird

So far, all of the 2.4 users in my club haven't have any issues that I'm aware of. But because of posts like this, I'll stick to my old tech 72, which have never had an issue.

FB

Rafael23cc

My Feedback: (6)

Have you noticed the flooding of "surplus" 72mHz equipment in the classifieds? Where do you think that equipment is going to end up? I can tell you where.... In the hands of budget minded people that do not want to spend the money for new good equipment, so the buy good second hand equipment. Did I say budget minded people? Do you think those people are going to spend the money in Club fees and AMA fees?

I hope you fly very far away from any parks, private farmland, or any place where a rouge RCers deems that it is "safe" to try his "new" 72mHz equipment.

That alone, is reason enough for me to completely swap to 2.4. Never mind model match, servo sync, and any of the other features offered by the technology.

Rafael

Zeeb

My Feedback: (41)

Probably 95% of the problems with Spektrum/JR 2.4GHz radios are power system related.

Quite a number of threads to be found like "Spektrum CRASHED my plane", "Spektrum LOCKOUT" or some such thing. Do a few searches as this has been covered time and again and I've yet to see more than a very, very rare occurence of a documented failure that wasn't user initiated.

While there have been a few documented issues of faulty hardware, most of those hardware related failures are traceable to rough handling of the components like cutting or pulling out the antennas and/or the same thing with the satellite rx leads. There are also great toubleshooting aids available with the Flight Log or built in fade indicators on some of the newer small rx's as well as the Quick Connect firmware which will tell you if there is a power system problem.

I think you need to do a bit more digging.

MikeL

My Feedback: (3)

It's the 21st century's "I got hit!"

snuts

This certanly sounds power related. Since 1992 I have been running dual battery/switches plugged into 2 ports on the receiver. With no power problems since, I've been glitch free.
With parrallel feeders to the power buss, this reduces voltage drop from the batteries to the buss. The first 2.4 flyer that can claim the symtoms you discribe while using dual power-in. Then I may question the equipment.
As of now I am a very happy, and confident J.R. customer
-Snuts-

MrCoffeeMax

So the battery pack supplied with the radios are not powerful enough? The DX7 comes with a 4.8v 1200MAh battery. The Futaba 7C comes with a 4.8v 600MAh battery. Why aren't Futaba systems falling out of the sky like crazy?

Are you saying that those Spektrum receivers that are "not as expensive" as Futaba receivers require the purchase of an additional $30+ battery pack? Where did those savings go?

Spektrum die-hards seem to put the blame for equipment malfunction on the user: YOU didn't have enough power. Let's see... 4.8v @ 1200MAh isn't enough to power a 4.8v, 6-channel radio?

What would they say if they bought a new refrigerator and it kept blowing circuit breakers, so they call the company and the rep told them, "Well, you can put a container of milk in there, and maybe a cup of yogurt or two, but if you put a turkey in there, you'll have to re-wire your house for 220 volts!"

yea, dig a hole and put your Spektrum radio in it! Or keep your Spektrum radio and let your airplane dig the hole for you.

Rafael23cc

My Feedback: (6)

Are we still talking about a Giant Scale Airplane here right?

I went a little off topic a little while ago, but it was to refute a point. We are still talking about a pretty large aircraft. If you are looking to save a buck here, you are in the wrong side of the hobby. Those battery packs might be good for 40 sized aircraft, but I would not have one anywhere near one of my big airplanes. The arguments about power problems all point to larger aircraft. I don't know of any complaints from the 40-size trainer crowd.

Rafael

MikeL

My Feedback: (3)

Ah, the joys of brand-zealotry.  I can't think of the last thing a particular brand name did for me in exchange for berating other brands online.  I must be doing something wrong.

Zeeb

My Feedback: (41)

What a conehead; OP is talking about 35% size model (composite arf 2.6M Extra) and you chime in with your orange shirt on, nothing useful to contribute and no desire to do anything but try and initiate another brand war.

If you're stupid enough to put a 4.8 volt 600mah battery in a 35% size model then it'll be you digging holes not me as my 2.6 Comp-Arf Extra is running dual A123's.

Now back to our regularly scheduled program of nitwits barging in on trouble shooting threads with nothing to contribute toward solving the problem....

jmohn

I can only share my experience on this issue. I had four planes go down from what people are calling a "lock-out" due to a "brown-out" condition. All the planes were electric and two were getting power from the BEC on the ESC and the other two from flight packs (2000 mah) nicads. All planes locked and stayed in the last throws on the servos. All were a total losss. I ended up testing 14 receivers at a local hobby shop and discovered if the power is lost or drops below 4.2 volts the receivers were going into a re-boot condition. This is what used to happen with 72 mhz receivers and we called it a "glitch". The Spectrum receivers are digital and need to re-boot. This can take 3-15 seconds acording to the tests we ran. Plenty of time to crash your plane. The new firmware with "quick connect" solves this problem and allows the receivers to remain locked on the last two good signals without a re-boot condition. The main problem, aside from the re-boot, was the BEC and battery packs were dropping below 4.2 volts on my planes. Mostly this was caused by high draw servos like the JR791. It was also caused by multiple servos binding. After upgrading to "quick connect" on all my recievers and using UBECs (regulators) with seperate battery packs (1320 or 2100 3S lipo packs) I haven't had any other issues. I have about 12 planes all on JR 2.4 using a 9303 radio. No issues and flying fine!


Jeff

Liqi

More Spectrum Problems. These problems were only experienced with a DX6. We have had two separate DX6's switch models by themselves. One time the guy was flying and it switched in flight and luckily the model it switched to was very similar and only caused his motor to die. The other case someone turned on a DX6 to fly a blade 400 that he had flown at least 50 times just fine. The model switched on its own from helicopter to airplane. It then had to be reset again.

Also in regard to the 2.6M extra crash, the receiver was an AR 9000 with 2 LI Po's regulated down.

Wes

jester_s1

Here's something I do that would prevent most of these types of crashes. I put a digital multimeter into a Y harness going into one of my servos and pull two of the servos down to their stall torque. It's a good way to check linkages too, but the main purpose is to tell me if my battery can do the job in a worst case scenario. I do this test before every flight while learning an airplane, then do a simple loaded voltmeter test after I get a baseline for what the system can do. This way, I know exactly what voltage is actually getting to the reciever with any given battery charge.

This test also comes in handy for checking servos for binding.

w0mbat

My Feedback: (1)

We have had at least 6 customers experience the exact same problem (plane flying straight and level then all the sudden nose diving in the ground) with the spektrum DX6, DX5 and the 5 channel receiver. I checked the voltage on each BEC under load and all were above 4.8v. Most of them switched to the Futaba system and haven't had another problem.

jmohn

Make sure the AR9000 has the quick connect feature. The first generation did not have this! You can check it by plugging in a servo to any channel and turning on the power then wiggle the stick for that servo and cut power off/on. The servo should only stop moving for a fraction of a second. If not it's got the old software and no quick connect.



Jeff

modeltronics

My Feedback: (27)

I usually stay out of these threads but this time I thought I would put my two cents worth in. There is some very good information in here and I hope to ad to it.

Testing a system with a volt meter will tell you only a little bit. To properly test your set up it takes a scope. Please don’t give me some heat about not owning a scope. To see what is going on with the voltage a meter will not do it because it is doing an average over time. The only way to see if you are going below reset voltage is with a scope on the system located right on the power bus inside the receiver. This is the only way you can see if the voltage drops far enough for two milliseconds. Even if you had a volt meter that did not average out the voltage your eyes could never catch it fast enough.

In checking out systems we need to look also at the voltage right at the battery with a scope and the voltage drop across the switch with a scope. Now to make this more expensive, I prefer to do all this with a storage scope.

Pete

Nakajima

Unfortunately, the average modeler does not own a scope, nor do they know how to use one. For the last couple decades, modelers have just connected their appropriate sized battery/bec to the receiver and flew. I find it very hard to believe that continuous low voltage is an issue when the problem only happens on Spektrum systems. Futaba and Hitec systems that I have used don't seem to have this low voltage problem. In every low voltage issue that I have experienced, the servos would slow down and have reduced torque. In the Spektrum crashes I have looked at, I haven't seen that happening. If for some reason it is just a millisecond spike in low voltage causing the receiver to lock out, then the receiver is still at fault and they need to look at a redesign of their system to compensate for that because it's not happening on Futaba and Hitec.

jmohn

All the newer DSM2 receivers from Spektrum have the "quick connect" feature and do not have the "lock out" from "brown outs".

That being said, I am sure there are LOTS of older stuff out there in hobby shops and garages that haven't had this problem....yet. I think most of the park flyers on systems with 4S or less will never see this problem unless they start adding more servos like required for retracts and stuff. Most park flyers are flying off grass and don't use retracts and larger digital servos that draw more power.



Jeff

modeltronics

My Feedback: (27)

Correct, I agree with you but that is why I asked for no heat on this.
As our radio systems get more complicated it takes more compicated tools to prevent or diagnose a problem.

If a set of digital servos has a 10 mSec inrush of several amps, the switch has a contact resistance of 300 mOhm and the internal resistance of the battery used is high, you will not see a reduction in speed and torque...but you may see a receiver reset.

Pete

w0mbat

My Feedback: (1)

I'm just trying to understand here - Let's say your servos are overdrawing the battery/bec for a few msecs. and it is enough to reset the receiver, wouldn't you see that on a voltage meter that is connected inline with the battery?

Mike

modeltronics

My Feedback: (27)

Hi Mike
No, you may not see it with a volt meter because the drop in voltage may be for only a fraction of a second. If this dip in voltage is for such a small time before it recovers the only way it will be seen is with a scope. Most volt meters are slow and average the voltage during this time. There are some very expensive meters that will do a hold durring the dip but this is not the common meter. Now, if the entire system is pulling down the battery long enough (many seconds) you will see it but from what I am seeing now it will take a scope in most cases. I hope this helps answer your question.

Pete

Liqi

The problem is not a voltage drop, two LIPo's going to regulators in an airplane with well over 300 flights on it. The servos were setup by me with no binding, they were the old plain 8611's. Before we installed the AR900 we did use a load meter(hanger 9 makes a meter that will show how many amps are pulling through servo.)

If the problem was a voltage problem I don't think we would have so many different planes crashed. I will SAY that no one has had trouble with JR equipment. Only spectrum radios! Like I have said before I am a Futaba guy, but I would trade in my 14mz for a JR if the JR was free...

modeltronics

My Feedback: (27)

Liqi
I'm not sure I agree with you. Can you give me the contact resistance of the switch harness you used? And I need the peak inrush current of the servos? Not just the average run current but the current draw in the first 2 to 5 mS at full load (the inductive inrush as the servo motor starts). These numbers change as the servos and switch are used more and more. Now I need to know about the regulator. How fast does it regulate and how stable is it?

I could not answer these questions on most of the models I have but I have made some measurments and seen a few things with a scope that made me wonder. As things age and get used in our system the numbers all change and not for the better.

I'm not trying to be a smart ***** but without the right data trying to know what the problem was for sure is difficult.

Pete

w0mbat

My Feedback: (1)

Funny thing is that I have seen spektrum receivers fail in the air and need to be rebound in order for them to work again. I don't know if that is still related to voltage issues. I have also looked at 3 other systems after a similar fails and sometimes they take up to 60 seconds after plugging in the battery before anything will operate - then they operate randomly. These all have been the new DSM2 receivers purchased within 3 months. All were sent back to horizon along with the speed controllers and no problems were apparently found. They did replace everything with new but didn't offer any solutions.

It seems the only solution is to run 2 nimh 3600mAh receiver batteries on every Spektrum system. Unfortunately, that alone weighs more than some of my planes!