Radio brownout - Lost another pair of underwear (and confidence in the plane)

[Sutton4211]

My dad had the same thing happen to him. It would lockout for about a second or two and then come back. It probably happened about two or three times and he just quit flying the plane because we couldn't figure it out. After it sat for awhile I needed two servos for my plane so I robbed two out of his elevator and put them in mine. Next time out my plane locked out and I had never had trouble before this. Sent both servos in and one of them was bad. I don't remember what was wrong with it and it worked fine but every so often it would draw too much current and the receiver would brown out. Not sure if this is your problem but it's a place to start.

 

[Sutton4211]

Forgot to mention we were not using a smartfly board. Just unregulated fromeco lion to the receiver. The smartfly may prevent what happened to us. Something to check into

 

[camss69]

So there's basically two things that can cause a loss of unregulated power without loss of regulated power: One is a faulty power distro and the other is a short in a servo or servo connection, provided that the SmartFly has some kind of over-amp protection on the unregulated rail (does it?).

So I guess the plan is to toss the power distro and put in a PowerSafe receiver. I was going to replace the elevator servos anyway due to slop. I don't think the IBEC is to blame, as it's on the 5V circuit which I don't think failed.

I stupidly shut everything down before checking the telemetry. Does anyone know if it keeps some kind of log somewhere for older flights?

I would put in the power safe RX and send the other RX into Horizon explaining what happened. They will check it out for free, more than likely you will only have to pay to ship it to them. Usually they don't even charge return shipping. I would also send the smart-fly in and have it checked as well. Keep them for shop use or toss em. Sometimes Horizon will just send you a brand new receiver which you could sell if you don't have a use for it.. This is your best option IMO because you eliminate that single point of failure.

As far as not knowing if the problem is fixed, you won't until you make some changes and try it!

 

[Bartman]

And I didn't want to say that, but as camss says, the power distribution systems really aren't needed. I'd remove it if it were mine.

an overlooked detail in all of this is that as system voltages go up, the amp/current draw goes down making power management systems even less necessary. if the receiver is limited to 10 amps and you're running 9 at 4.8 volts, bumping the voltage to 7.4 actually makes the total amps draw less (in this example it would be about 5.8 amps). this makes the servo power bus in the receiver actually better suited for the job of powering the servos. just don't use higher voltage than the receiver is rated for, but you guys knew that.

@njswede how many servos are you running in that airplane? what manufacturer/model?

 

[njswede]

(Nitpick) It's only partially true that higher voltage always means lower amps. Servos are usually rated for higher torque on higher voltages, so for the same torque, yes the current if lower. But not if you max out the servos, since the max torque is higher.

I have 7 Savox 1270TG (4 aileron, 2 elevator and 1 rudder) and a Savox 1272SG on the throttle.

 

[Bartman]

yes for a particular set-up. if you put them into a higher load situation then yes the amps go up but you might still run lower amps then on a lower load with lower voltage.

it's been a while since I tried to measure amps through servos. might be a good project for the website to demonstrate what is being drawn in different applications compared to what the current lineup of receivers can handle.

 

[njswede]

I told you it was a nitpick!

If the kids and wife will leave me alone today, I'm going to run the power through a wattmeter and see what my draw is. I'm expecting it's not that high, because I could only see 0.2V sag when I held down a control surface and moved the stick. Something catastrophic happens under some condition. It drives me NUTS!

In other news, I checked and the only PowerSafe RX I have at home is an old JR R12222 (DSMX upgraded). Not sure I would trust that more than the SmartFly...

 

[njswede]

One theory I have is that since this happened just after I put cans on the plane, there may by some heat buildup inside the fuse that causes the problem. Head temp clocked in at 262F after a normal flight and I think the cans may get even hotter. Maybe there's heat transfer up to the electronics. May make sense to bring out an old hair dryer...

 

[Judge]

if the receiver is limited to 10 amps

Couple of comments.

I have never seen a "power rating" for a receiver, or a "limit" published , for any brand.

I have asked people who would know if either one of the 2 major brands have ever seen a receiver in their service center that was cooked due to being "over amped". Neither one has.

I witnessed a beer driven experiment with a brand new RX several years ago where a steady 6-volt load was applied to it and the load increased slowly in 5 amp steps to see if it would fail. It did, at around 80 amps. And that was after several seconds at that load.

Conclusion? Worrying about cooking a RX due to much load is really not something that is possible under even the most extraordinary situations for us.

 

[Judge]

One theory I have is that since this happened just after I put cans on the plane, there may by some heat buildup inside the fuse that causes the problem. Head temp clocked in at 262F after a normal flight and I think the cans may get even hotter. Maybe there's heat transfer up to the electronics. May make sense to bring out an old hair dryer...

Heat is one of the prime enemies of electronics. My Garmin GPS will stop working if it sits in the sun on a hot day. And Futaba had an issue with the 6014 (first batch) several years ago where they got a batch of chips that were slightly out of spec which made they RX sensitive to high heat.