Problems!! 14MZ 2.4 R6014FS

[freya1]

The set up in the QQ Python that I saw fail was also a staight forward set up, nothing fancy, Duralite Batteries and Regulators with each servo plugged into its own channel and a very clean set up, but the RX was also mounted High up in the fuse by the canopy, and I saw it fail as he landed the plane and was taxiing back to the pits, and a couple times more as we were holding the airplane trying to figure out what was happenning.
And as far as wanting a fast solution, that wasn't the case, he was just mad at the way he was treated by the person at Hobbico and the response he got, he was just told there was nothing wrong with the RX and TX, and that is all they could do, instead of saying something like we will contact Futaba and will try to find out if anybody else is having the same problem and maybe try to figure out what happenned and try to find a solution.
"WE JUST WANT A LITTLE BETTER CUSTOMMER SERVICE"

[xcellheli]

Some will disagree, but I think Futaba is very proactive and does a good job of informing customers in a timely manner. Spektrum stated for over a year they didn't have a voltage cutoff problem and suddenly there is an update for free to fix the problem that didn't exist. If Futaba notifies us in a week or two it will be a great response time. Go Futaba!!!!!

[Radioactive]

Ditto that... Futaba has a protocol, policy, and procedures to follow, just like any responsible company does!!!!!!!!!!!!!!

[klhoard]

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Well, if Futaba's "Pre-Vision" technology was any good, it would have seen this one coming . . .
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[dick hanson]

	Quote: Originally Posted by klhoard
	. . Well, if Futaba's "Pre-Vision" technology was any good, it would have seen this one coming . . . . .

Do you get a free white cane with that?

[Kiwi]

Wow you guys are sure fast or is that FASST to shoot the messenger. I posted that 1600 degree thing because I seen it on a FUTABA post. Error or no error it is and surely could be possible that chips or whatever can run at super temperatures (hot or cold) yet the external surface not get hot.

Heck I mean back in the 70's when you were putting people on the moon they made insulated cylinders on Apollo that would keep an ice cube frozen for 200 years if you did not open it. The shuttles heats up to 3000 plus degrees but I dont see the astronauts with burned feet when they land.

Anyway it was a typo and thats solved.

Back to the subject: In our summer its easily in the mid 30's and while we dont have a lot of FASST systems flying there have been a few and so far touch wood no issues. I'm sure the Futaba engineers are deep into this looking at it from every aspect. They cannot give a knee jerk reaction as thats actually more damaging than doing it slower and carefully.

As for the response from product support, yep that sucks.

In my business the customer is always right until proven wrong. Where there is smoke there is fire and I'm sure just like the other 2.4Ghz systems we the end user have possibly uncovered an unforeseen bug.

Its not the first time, it wont be the last but I'm sure they will fix it if it needs fixing.

[tony-amps]

Good info guys keep it comming.

Tony

[reyn3545]

I wrapped the receiver in 2 Hitec receiver foam sheets (pretty high density foam, should trap at least as much heat as the white foam) and tested the receiver for 10 minutes. Results...

Starting temp... 70 degrees (room temperature)
After 3 minutes... 74 degrees
After 10 minutes... around 80 degrees. The center of the top side of the receiver seemed to be the hottest spot, at 84 degrees.. still well within operating expectations.

So, if the receiver is shutting down due to a thermal incident... based on my very unoffiicial test... it would have to be ambient heat that's causing the problem, not the receiver. Now, I don't know what the ambient heat spec is on the unit, and again, if you've got a heat generating device wrapped in foam (at any ambient temp) its going to be measurably hotter than the ambient air itself.



In the end, the only "official" conclusion I can draw is that the weather in Atlanta is pretty nice this time of year... wish I was flying instead of working!

[martin18152]

I use to work in the military electronics business years ago, and there were all sorts of ESS programs to test thermal / vibration environments, these tests were done on 100% production units, at various sub assemblies. The trick was to pick test parameters that sufficiently stressed the component / assemblies, with out degrading its useful life. I doubt Futaba dose ESS on a 100% basis, you probably could not afford the product if they did. I would hope they do some, on a sampling plan, but who knows. I will bet they are probably doing a little right now. Some times big problems are connected to the simplest fix, that’s engineering, and I’m sure Futaba is working on it. Thermal profiles are very complicated, and I wouldn’t try to guess the problem. Simple thermal profiles show a linear decrease in temperature from the high T1 to low T2; however, the rate of heat transfer in nonlinear and very complicated. In this case you have a lot going on, radiation from the sun, radiating heat out of the receiver, internal generated heat by components, convective air over the case, and some heat generated convective air inside the case. You could eliminate the sun radiation by putting the receiver under some balsa or by using non insulating shield, that would eliminate one complication and would not hurt; however, heat transfer will stop once T1 = T2 regardless of the sun radiation, if T1 is your internal heat generator, it will continue to rise in temperature until T1 > T2 and energy will then continue to transfer from T1 to T2. Since the heat generated in the unit is fairly low in frequency, the rate of heat transfer out of the case by radiation is probably insignificant, where on the other hand the frequency of heat generated by the sun is very high, and the transfer rate is very significant into the unit – for this reason, it confuses me on why futaba makes their cases black, unless they plan on the units being in a dark place (classically that’s the way it use to be prior to the giant scale revolution with huge canapés) , then emissivity would dictate energy to flow out of the receiver by radiation. The amount of energy transfer is dependant on the geometry of the conducting / radiating surface. Energy can be transferred along board traces to the buss, and out through the servo control wiring. Once again the power box, or power distribution system would help, buy reducing the current through the receiver buss, therefore increasing the heat transfer.

This is my opinion, and I plan on doing the following to make me feel better, since I have no direct knowledge of the problem, and I have not had any problem with my present system:

• Do not put the receive in direct sun light under the canapé, you can put it in the fuse, I doubt balsa and covering will block 2.5 GHz signals - maybe not the case with carbon fiber fuselage.
• Use some sort of power distribution system that reduces the load to the receiver buss
• If you have to put the receiver in sunlight, reflecting shield the receiver with a non insulating cover, that allows airflow over the receiver.
• Cover the canapé while it sits on the flight line, this should be done regardless of your receiver, I have seen canapés warp / melt on sunny hot days, so most people do this anyhow.
• Do a prolonged ground check prior to flying; chances are if heat is the problem, it will show up on the ground before you fly. I can say this will work with full canisters exposed to the inside of the fuse.
• Have Futaba hire more Mechanical engineers, thay are better a thermal dynamics than electrical engineers, lol, just kidding.

• If futaba has a design problem and it sounds like there me be some undefined issue, wait for futaba to better Idiot proof their system, and still do all of the above.

[grayuk]

I am new to Giants and have just come across your thread.
I fly FASST in all my models now and am 100% sold on the technology and reliability. I fly 3 jets on the system with zero problems.
This problem concerns me as it would anyone.
I have read through the thread and please forgive me if I am stating something that has been covered.

My understanding is that the problem showed up when models were left in the sun.
When placed in the shade the problem went away.

My question is this.
Has anyone tested JUST the rx in this temperature test?
i.e. the rx only out in the sun, all other items in the shade or cool?
This is the only true way to say that it is definitely the rx.
Could it be another piece of the install causing the voltage rail to drop below 2.4 volts which I believe it the voltage at which the rx gives up?
Can you duplicate the failure and monitor the voltage rail?
Just a few thoughts…
Paul

[Leardriver]

Has anyone tested JUST the rx in this temperature test?
i.e. the rx only out in the sun, all other items in the shade or cool?
This is the only true way to say that it is definitely the rx.
Could it be another piece of the install causing the voltage rail to drop below 2.4 volts which I believe it the voltage at which the rx gives up?
Can you duplicate the failure and monitor the voltage rail?
Just a few thoughts…
Paul[/quote]


Go back to my earlier post on this thread and you will see where I took two brand new receivers out of the package (a R6014FS and R607FS) with no servos connected and took a heat gun and a IR Temp gun and watched them fail (go red) at 167 deg ad 168 deg respectively. That was the temp on the top of the case on each unit. Almost to the degree that the previous units were reported to fail.

If any of you guys feel inclined it would be very interesting to see if the experiment can be repeated again. The inside of these planes can easily get to these temps in the warmer months. In my opinion it is clearly a heat issue, not a voltage problem.

PaulP

[grayuk]

Thanks for your quick post.
OK it would seem to be the rx.
I wonder if the problem is just ventilation on the case.
I ca not believe that these chips are of a lower spec than the ones in the old 72mhz/35mhz rx’s.
What is very different is the case.
The old rx;s had holes for xtals etc and where not so tightly sealed at the new range.
The surface area of the case is also much smaller; as a result it has less ability to dissipate heat an dhas a smaller vol. of air so it warms up quicker.
I wonder if you would get the same results with the rx case top removed?

Paul