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Radio - Futaba FASST > From the Futaba Forum........Heat and 2.4Ghz Rx!
 
 
SceaduFan
Senior Heliman
Location: Phoenix, AZ

Put your setup into an oven and watch the receiver go all red at 164f and no, nothing melted. It just thermals out and comes back at around 135f.
05-01-2008 04:32 AM
 
 
rexxigpilot
Senior Heliman
Location: florida

OK, I thought the claim of the receiver temperature getting to 164°F with an ambient temp of 115°F was suspect, so I did some testing last night and this morning. Here's what I did and found. I took one of my 6014 receivers and hooked up 3 BLS451 servos on cyclic/collective channels and a 9252 on throttle channel, placed a masonry brick secured with servo tape on each of the 451's as load (had to use lead extensions on 451's due to their short lead length), then rapidly and continuously operated the system for 15 minutes. Input voltage was from a standard, 4 cell NiCad pack. I measured the pre test and post test temps of the receiver under two different ambient temperature conditions. The first test was with ambient room temp of 70°F. The second test was a hot ambient condition of 115°F, which I achieved using the proofing drawer of my kitchen oven.

Results: test 1 - pre-test temp. = 70°F, post-test temp = 82°F
test 2 - pre-test temp. = 115°F, post-test temp = 124°F

The temps were measured at the top of the receiver case near the power bus using a Duratrax Flashpoint gauge. This turned out to be the hottest place on the outside of the receiver with my test setup. As the results demonstrate, the change in receiver temp above ambient was only 12°F for test 1 and 9°F for test 2.

I'll let you all decide if someone would really get a temp difference of 49°F using a proper installation. I say this is BS!
05-01-2008 01:33 PM
 
 
greg
Key Veteran
Location: Yorkville, IL

You guys are missing his point. Get a shoe box, cover the inside with black construction paper, set a receiver in it, cover the top with saran wrap and put it out in the sun. Wait 30 minutes. How hot is the reciever? You have essentially created a mini oven, which is almost the same circumstance as the inside cockpit of an airplane left in the midday sun.
05-01-2008 01:48 PM
HOMEPAGE  
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Greg is right, some of you need to re-read the OP.

The system in question was NOT OPERATING when it wouldn't come online. It was sitting IDLE on the GROUND when the temps got above threshold. The problem didn't surface until they went to start the plane for another flight.

What we need to do is lock some of you guys in a black car with the windows rolled up for an hour in the sun.

I think folks are so darn paraniod about batteries and switches and regulators and servo loading, etc etc etc, it's the first thing out of anyones head, irregardless of what they just read. While a great many problems are due to batteries, regulators, and servo loads, this is not such a case. In the given experiment, they could have attached a 600mAh pack and one 9202 servo and gotten the same results.

The only real question in the posted results is how accurate that temp gun was. The actual temp might have been higher or lower. I am satisfied with the conclusion that the receiver did shut down at a given, repeatable temperature.

If the receiver didn't cost $220, I'd do an experiment myself...but I need my receivers too much to abuse them on purpose like this
05-01-2008 02:40 PM
 
 
wonderboy
Senior Heliman
Location: Southeast, MI

My question about weather or not an external regulator was in the loop is valid. The regulator WILL have a thermal shutdown limit. I have no idea what the limit may be on these devices, but they absolutely DO have an upper limit beyond which they WILL STOP operating. Now, this limit may be well beyond the temps we are talking about, but my question was just to start understanding the situation a bit more. The scenario I was thinking about was if the regulator (if one was installed) was also hot, maybe it was at or near it's thermal shutdown limit.

Again, I'm not saying this is a power issue, but I would just like to understand the setup a bit more to see how similar any of my setups are to the one in question.
05-02-2008 02:21 AM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Understood...it wasn't clear that you were investigating a similar, but separate, issue. I would agree that it would be good to know if some of these regulators have a thermal cutback threshold we should be cognizant of.
05-02-2008 02:32 AM
 
 
SceaduFan
Senior Heliman
Location: Phoenix, AZ

It was not a regulator problem as the light on the receiver was still operating (but is was red). If a reg thermals out, there will not be any power to any of the electronics in most cases. Also, the failure in the receivers was isolated down to a specific, common chip on the boards. This definatly was not a reg issue.
05-02-2008 03:02 AM
 
 
rexxigpilot
Senior Heliman
Location: florida

Didn't Flying Tivo, the original poster, contact Futaba on this matter? Any word from them yet?
05-02-2008 01:37 PM
 
 
wonderboy
Senior Heliman
Location: Southeast, MI

Myth Confirmed!

Myth Confirmed!

I just got done testing my R607FS receiver in our environmental chamber at work (shhh, don't tell my boss).

I had the receiver inside the chamber. I ran a battery lead out of the chamber and used a lab power supply set to 5.25 volts. I ran a single servo lead out of the chamber on channel 1 so that I could confirm function throughout the test. I attached a thermocouple lead to the receiver case to read the Rx temperature. I also had an ambient air thermocouple in the vicinity of the receiver.

After zeroing in on the critical temperature, I found that after soaking (thermal soak) for 10 minutes at 140 degrees F (ambient and Rx case), the light on the receiver was red and no function was observed on the servo.

I then turned down the temperature on the chamber to 137 and let the setup soak again for about 10 minutes. The ambient and the case both reported 137. Proper operation was restored. The light was green and the servo functioned.

On a side note, I was surprised that the chamber didn't shield the signal from the Rx. The chamber is a completely enclosed metal case, with only a 2" hole through the side to pass wiring. I was able to control the servo with the Tx outside the chamber and the chamber door closed.

Once I observed failures, I opened the door and held the Tx at the opening just to confirm that the chamber wasn't somehow shielding the signal.

So now the question is: What are the chances of my Rx getting up to 140F?
05-02-2008 06:11 PM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Good work, thanks for bringing in some good, calibrated equipment into the mix. I was also having a hard time believing that the inside of that plane was 164°F, which is why I questioned the accuracy of the temp gun.

The original premise remains, there IS a temperature cut off threshold we have to be wary of.

The good news for us is that it'd be pretty hard to get that kind of temp under the canopy of a heli, as it's not really sealed enough to "green house" up in temp like the canopy of a large plane.

Also, more good news in that this is an anomoly that presents itself on the ground, before flight. Unless your RX is under the engine or muffler, it's highly unlikely that this will occur in flight.
05-02-2008 06:23 PM
 
 
MrMel
Elite Veteran
Location: Lidingo, Sweden

if you can, test a 401 gyo at 140F, I think its rated only for 113F or so.
05-02-2008 06:32 PM
 
 
wonderboy
Senior Heliman
Location: Southeast, MI

Monday on the 401.

Thinking of trying an old 72 MHz system as well.
05-02-2008 08:05 PM
 
 
I3DM
rrProfessor
Location: Israel

Yesterday i just witnessed the same thing when my friend had his 2 jets (R6014 Rx) sitting in the sun for a while and after turning the Rx on, it would work for a few seconds and then freeze with the RED light... and yes the Rx was hot in the sun.

Team pilot for RJX, Helidirect, Logictech, ThunderPower, Fromeco
www.liorzahavi.com
05-04-2008 02:02 PM
HOMEPAGE  
 
 
rexxigpilot
Senior Heliman
Location: florida

One of the first things I learned about RC modeling was to keep the model out of the sun until ready to fly! I guess that still holds true after almost 40 years.
05-05-2008 10:12 PM
 
 
steph280
Key Veteran
Location: Irvine, California

Any word on the 401 temp test? I'm curious...
05-06-2008 04:07 PM
 
 
Four Stroker
Veteran
Location: Atlanta

The 401 instructions plainly say -10C to +45C. So if the ambient temp gets above 113F in AZ, you are probably toast and the receiver fails later at 140F. Alternately, if you fly in 10F, both the gyro and receiver crap out.
05-06-2008 07:53 PM
 
 
Freakout
Senior Heliman
Location: CA

Man! At first my 5014 locked out. And now my 6014 ready to install, I guess I will wait for 6114.

Magic's in the air!
05-06-2008 08:43 PM
 
 
Knud Pedersen
Veteran
Location: Denmark - Europa

ggeee, I just installed the 6014 in both my Stratusses.....
Thanks God, I live in Denmark, were 6n a very very good summer day almost never is 28°C.....

Whats futaba doing

Chopperknud

Knud Pedersen
05-06-2008 09:15 PM
 
 
ErichF
Key Veteran
Location: Odessa, FL 33556 (Tampa Area)

Why are you all so paranoid? This doesn't happen in flight, only if you leave your bird out in the hot sun...plus, this hasn't been duplicated in a helicopter. Our canopies aren't prone to greenhouse like planks are.

I'd rather the unit shut down if it gets THAT hot, rather than toast itself.
05-06-2008 09:22 PM
 
 
steph280
Key Veteran
Location: Irvine, California

Yeah 164F is actually quite high. We only see that type of temperature on our ESC/motor which pumps 2000+ watts through. With the airflow our heli gets, I doubt you can get that type of heat on a receiver unless you enclose it in a black box with one side being transparent and exposed in sun (IE the canopy of a fixed wing model).

If any of you want to abandon the FASST camp and sell off your equipment, I can use a few cheap 6014's. I am sure you will have better luck with the Spektrums brownout issues.
05-06-2008 10:02 PM
 
 
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Radio - Futaba FASST > From the Futaba Forum........Heat and 2.4Ghz Rx!
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