Has anyone ever had a module fail?

[Wojcigitty]

Recently, I had a module fail in my Futaba 9C. It started like this:

At the fly-in last summer in Woodstock CT, where I met Tank, Snap, RH, Klown, Brimma, and the general CT FG crew, I flew a couple freestyle demos with my Carden 40% Extra. On one take-off, the tail popped off of the ground. I thought I had hit a bump with the tailwheel, my dad thought I had popped the tail off purposefully. When reviewing video much later, it was apparent that the elevators had actually gone to full down for a split second.

Then, at the recent Salem CT IMAC contest, the plane seemed to hesitate in two of my point rolls for longer than it should have. I figured that the issue was just due to wind, as it was quite breezy, so I put it aside. Later, when flying, I got another such lock-out glitch on a calm day. I realized something was up and landed. There were brass straps screwed over the RX and servo bus holding them down, and I thought they were vibrating every now and again and causing the interference. I replaced them with plastic.

Jump to Thursday night, it was training night at my local field. After saving a couple of trainers from certain doom and yelling at students until the cried (you need to be firm with them), I decided to fly my Fliton Inspire. It's also on PCM. I started it, took off into a rolling turn, then tried two quick rolls. It did two and a half. I regained control, flipped it upright, and landed it. On the way in to the landing, it was terrible. The plane is normally rock solid, but it was incredibly mushy and sluggish, due to the servos intermittently locking up. I got it down and killed the engine. Doing a range check, I couldn't get more than five paces from the plane and still have control.

I swapped the module with that in my dad's radio, an old 8U. My radio worked perfectly controlling his airplanes, but he had the same problems I did with his radio and my airplane. We felt the modules, mine was warm to the touch, his wasn't. We waited an hour and tried the tests again, and both transmitters and modules performed flawlessly.

Friday I called my local hobby shop (RC Buyer's warehouse). Unfortunately they didn't stock Futaba modules, but they had synthesized modules. I picked one up and dialed in my channel. Range checks went fine on Sunday. I swapped the channel to that of one of my dad's slightly beat airplanes to use as a guinea pig. It worked perfectly. I swapped the channel again, and tried my Inspire, no glitches. After a couple deep breaths and every ground test I could imagine, I flew my Carden. The plane was rock solid.

So, it seems as if the module died for no reason at all. I was very lucky to have it fail intermittently with a plane that's easy to land. Keep in mind that this thing is at least four years old, maybe five or so, and is used a lot (the chrome on the transmitter is wearing off). I also fly on my sim quite a bit, without taking the module out (but I never guessed that there would be a reason to).

Has anyone else had this issue? Does anybody have any guesses as to what caused it? My guess is just an intermittent connection on the PCB or some stupid manufacturing defect like that.

[Kiwi]

When your flying on your SIM you have the antenna down I assume. I mean I am sure its down.

That will without a doubt kill the module. The reason will be explained better by someone else I know but by having the antenna down your module does not get rid of the radio energy they way it should. It somehow feeds back into the module, it gets warm and gives up the ghost in the end.

Thats as rough as I can mechanically put it. Some electronics guy will tell it like it really is I'm sure.

[3ddd]

always take your trans module out when on the sim

[OverTemp]

I didn't think the module was power when plugging into the sim, or is that only with JR? Pardon my ignorance of Futaba.

[Wojcigitty]

Fair enough, I'll take it out from now on.

But, the transmitter isn't transmitting when on the sim. The radio only turns on when on the cord is plugged into the buddy box cable automatically to power the procesor.

So, the transmitter should be in the same situation when being used as a buddy box or when on the sim. But I guess you're not using it for hours at a time when used as a buddy box.

[Stainless Skills]

Can this happen on a really hot day, I had a pcm lockup with my 9303 on a 95 degree afternoon after my radio had been in the sun for hours and after 5 flights?

[klhoard]

The power transistor in any module has a finite lifetime, and I have also heard that running the RF section with the antenna down is very hard on the module. If you're flying big airplanes around other people, the responsible thing to do is send in your radios and modules every year for a full checkout. Like replacing your batteries, it is cheap insurance.

Send an e-mail to Tony Stillman at Radio South, he will let you know what you need to do.

[RappyMan]

I have a problem with my TX (8U) and the electric airplanes. I leave the TX on so as to not get a glitch & have the prop bite me - also set the TX somewhere safe so it doesn't get bumped. Grab the plane, pull the battery... usually go put the LiPo on the charger... and forget the TX is on. Probably 4 times this year... wake up to the beeping sound of a low TX battery. 2500's last a long time!
The TX/module is tuned to the power needed when the antenna is up - matched power circuitry. When the antenna is down, much less power is used & there is a mis-match that makes the radio or module get hot. I ran across this info awhile back... put the antenna up if leaving the radio on overnight to cycle the batteries.

[ZXPilot]

I think I may have experienced a similar situation three days ago. I was flying my 33% Yak straight and level getting ready for my next manuever when an uncommanded pitch towards terra firma grabbed my attention. The pitch command was brief but very deliberate. I landed as quickly as I could while enduring two more pitch down commands in the process. I managed to get the plane down unscathed. It wasn't until the plane was safely on the ground that I noticed my fingertips were hurting or I should say burning. The module on my 9C was very hot to the touch. I had never experienced that before. I have three 7UAFs that I still fly with and neither of them have had the frequency module get hot to the touch or even warm from what I can remember. Being that it was 110 degrees at the field that afternoon I figured the temperature was getting to the equipment (and me). I decided to pack it up for the day.

This was the first flight of the day for the Yak but the fifth flight for the transmitter. I had been flying my Giles up until then and I did not notice any issues. I haven't turned the transmitter on since that day and I planned on conducting some checks of my own but after reading the experiences here I am not taking any chances. Modules are relatively cheap but I think I will send the transmitter in to be checked. There was a lot of heat generated from the module. It only makes sense for me to play it safe.

Anthony

[JimC-MD]

I fear your module must have been contaminated with 2.4G emissions. From what I read on the net, we never had any trouble with the old stuff and these crazy issues are only with the new technologies.

For those that could not tell............ I AM KIDDING

I have heard of this type of thing before. Electronics fail at times in various ways. Heat tends to be a common trigger. Glad you did not have a large catasrophy and your testing of the cause looks sound.

[alan anderson]

I JUST WENT THREW THE SAME TYPE OF PROBLUM. IT SEEMED LIKE I WAS GETTING GLITCHES. I BLAMED EVERTHING EXCEPT MY TRANS. REPLACED REGLATOR, POWER EXPANDER RECIVER , IN THE END IT WAS THE POTS IN THE TRANSMITTER. I SENT THE TRANSMITTER INTO FUTABA. THEY REPLACED 4 STICK ENCODERS, 4 RESISTORS, THE TOUCH PANEL ON THE 14MZ. AND RETURNED IT OVER NIGHT. WORKS GREAT. DON'T HESATATE, RETURN TRANS TO FUTABA. GOOD LUCK

[3ddd]

heat is a killer of anything electronic,never leave your tran in the sun to cook it will fail after a few times of cooking it.yes the trans module will backup the rf power with antenna down and also cook it.these are just like your computer at home but people get hurt when these fail the only one that get hurt if you cook your ibm is your pocket book.treat them with respect or pay the fiddler later

[Wojcigitty]

Here's a bit of an update. I asked on RCU in the Futaba support section about whether or not to remove the module when using the sim. There was some discussion, all of which got deleted because those discussing it were not Futaba support people. Finally, Bill Baxter said "Remove the module," and nothing else.

I tried a little experiment. I hooked a receiver, battery, and servo up, and turned on my transmitter. I was able to control it. I turned the transmitter off and plugged it into my sim cable. I could not control it. So, there should be nothing being emitted when running on the sim, it should be in the same situation as when being used for a buddy box.

Also, all of my problems with the Inspire came back. I did some more testing, and I think I've got a bum RX in that. I'll replace the receiver. I'll bet that my original TX module is perfectly fine.

[Tired Old Man]

I had one on an 8103 that changed it's tuning. The cause seemed to be my forgetting to turn off the radio and running the battery flat with the antenna collapsed.

[rcflyer]

Most of the Futaba adapters for sims actually disables the RF circuits when plugged into the Tx. You have verified that to be true. In that case, there is no need to remove the module when simming. OTOH, repeated removal of the module may cause the solder joints of the module connector pins to crack and cause intermittence.