7PXR Failsafe Mystery-thoughts/advice

[Jason O'Brien]

Thanks for all the questions and advice. Haven't had internet access for a while. I'll try to answer a few things here:

Grim; I don't think it's fuel related in any way. This motor has been run harder, at higher RPM's, for lots of laps. The original tank was built by John Steltzer. His craftsmanship is excellent, and he & I discussed this at length. He give me test instructions, then I sent it to him, and he tested it. It's fine. It also did the same thing when I modified a 10oz Dubro tank with 5/32" lines. Pickup bottom/rear/center, pressure up high. Plus, when I switched the radio, it ran flawlessly, even with my repurposed/modified Dubro.

John; the antenna may not be exactly 2" above the pipe, but it's close. I was very careful to get it as high as possible (with the stock antenna lead). Never thought about it until you mentioned it, but it has always been L to R. There may be something to that, or it may be that I always start a pass in that direction.

Daniel; I have not tried a fresh model number. That's a good idea.

Tyler; never thought of that. I'm not sure I'd have even thought to consider resonance. Someone told me a couple of days ago that Huntsville was always problematic, and that it'd be a good idea to get my antenna a solid 12" above the radio box (because that's what seemed to work there). I haven't done that yet.

I obviously need to run again, with the 7PXR, original Rx, minus the GPS, and see what the results are. Not sure if I mentioned it, but that hardware combo (with the GPS) has lots of successful hours on it. I didn't see an issue *until* I started pushing 3-digits. Again, I realize how dumb that sounds, whether I say it or think it, and realize it's probably NOT the GPS, but that's why I asked for help. I'm stumped right now. I do have to say...Danny King has been telling me "failsafe" (or at least radio issue) from day 01. I typically (read: always) kick myself, later, when I don't listen to him.

 

[Daniel's Racing]

The other trans/receiver already confirmed it is the radio.

Do you have a ton of models in it that would be a royal pain to recreate all your settings again ?

Try just a model number change and if still doing it then a factory default reset may be next step. It sure does sound like failsafe issue or other type brown out but with it chopping the throttle that is a command the servo is receiving otherwise it would not slam shut but more likely to stay where it was unless failsafe is taking it to a preset position.

Your positive you failsafes are off on all channels ? .

 

[Danny King]

His radio is fine he just wanted a way to let you all know he is running 98 mph. Lol

Crazy how things happen. Lot of things have to go right for these things to run great.

 

[Rich Jones]

Have you done anything with the switch? I was having some strange behavior on the throttle servo on my Slingshot recently. The throttle would operate normally but when I would start the motor, the throttle would ramp up and down without any input. Shut it off, the throttle would return to normal. I use a 7PXR with a R334-SBS receiver. Failsafes are set on both channels and battery and I use the GPS sensor. I thought the receiver may have gotten a bit wet so I let dry out and used silicone conforming coating to coat the receiver board being careful not to gum up the pins, antenna connections, or linking switch. Next time out boat did it again after a couple runs. I use a waterproof locking toggle switch attached through the lid. I get these from Daniel Place. I love them. But this particular switch seemed to have some water getting on it and had a black stain on the side like it was shorting out. Just for kicks I had another and changed out the switch. Had a good final run that day and then went out last Thursday and ran several multi lap sessions with no problem. It would appear to have been a shorting switch and the vibration from the motor was enough to make it go wacky. Now maybe when YOUR vibration level gets to a certain point (98mph perhaps) something like that is happening. I don’t know, worth looking at. The GPS wouldn’t have any impact on any other radio functions. Could there be some strange interference going on with the gps? I don’t know, I don’t think so, but don’t really know for sure. I didn’t try to run without the gps but the switch seems to have fixed the issue.

 

[Jason O'Brien]

Have you done anything with the switch? I was having some strange behavior on the throttle servo on my Slingshot recently. The throttle would operate normally but when I would start the motor, the throttle would ramp up and down without any input.

YES!!! This was actually my very first thought (after Danny told me he thought it was a failsafe issue). My thought was, since low Rx battery voltage is the only failsafe I have enabled, that the switch (same kind you have) was either vibrating or something was getting pushed around under hard acceleration (telling the radio to shut down). I built a little plastic plate on one side of the terminals, and filled in/around the terminals with epoxy to stop any of the wires/connections from jiggling. To your point, there could be some corrosion in the switch I suppose, or the switch contacts could be excessively vibrating?

I shelved this idea when I pulled the logs, because I've never seen the Rx voltage drop (in the logs). Now that I think about it, I suppose the dropout could be happening faster than the sample rate??? Maybe something about the 3PK makes it less immune to this, and that's why the problem went away. I did test the switch extensively after adding the epoxy, but I obviously don't have a way to do it at 25k RPM...I'll change the switch AND run w/o the GPS this weekend.

I guess the switch is the only part of this deal not isolated in a foam cushion, so it makes some sense.

 

[Mike Cathey]

Easiest way to find out is to go around the switch and plugging the battery directly into the RX and if the problem goes away you have your culprit. I think bad switches account for a lot of totaled boats from radio failure I've seen over the years. You can't see the corrosion. One of the really great things about using waterproof radio gear is that the switch is eliminated.

 

[ACTION JACKSON]

Would be nice if you had a way to take the boat for a ride at that speed to see if it shuts down at that number or if vibration is still a possibility. You have a friend with a plane you could test that way & at same time enjoy the day in the air or fly to a restaurant some place.
Yes it's a far reach ,but nobody has found the answer yet. It's just safer in plane than car. Not sure about all the metal that could cause interference. The resonance could be the big answer, BUT is it possible to check the solder weld of reciever antenna. Have you bent or kinked the antenna, this will be a problem. Good hunting.

 

[Grimracer]

Thanks for all the questions and advice. Haven't had internet access for a while. I'll try to answer a few things here:

Grim; I don't think it's fuel related in any way. This motor has been run harder, at higher RPM's, for lots of laps. The original tank was built by John Steltzer. His craftsmanship is excellent, and he & I discussed this at length. He give me test instructions, then I sent it to him, and he tested it. It's fine. It also did the same thing when I modified a 10oz Dubro tank with 5/32" lines. Pickup bottom/rear/center, pressure up high. Plus, when I switched the radio, it ran flawlessly, even with my repurposed/modified Dubro.

John; the antenna may not be exactly 2" above the pipe, but it's close. I was very careful to get it as high as possible (with the stock antenna lead). Never thought about it until you mentioned it, but it has always been L to R. There may be something to that, or it may be that I always start a pass in that direction.

Daniel; I have not tried a fresh model number. That's a good idea.

Tyler; never thought of that. I'm not sure I'd have even thought to consider resonance. Someone told me a couple of days ago that Huntsville was always problematic, and that it'd be a good idea to get my antenna a solid 12" above the radio box (because that's what seemed to work there). I haven't done that yet.

I obviously need to run again, with the 7PXR, original Rx, minus the GPS, and see what the results are. Not sure if I mentioned it, but that hardware combo (with the GPS) has lots of successful hours on it. I didn't see an issue *until* I started pushing 3-digits. Again, I realize how dumb that sounds, whether I say it or think it, and realize it's probably NOT the GPS, but that's why I asked for help. I'm stumped right now. I do have to say...Danny King has been telling me "failsafe" (or at least radio issue) from day 01. I typically (read: always) kick myself, later, when I don't listen to him.

Just asking questions.. incase something clicks!

Grim

 

[Mark Bullard]

We had Futaba come and setup at the NAMBA Nats in Huntsville. Since they are in Madison next to Huntsville. They were there for support and repair. They fixed a lot of radio problems that racers were having. And did a wonderfull job. They done some testing with one of my boats with one of there GPS module. It worked great. I bought 4 of them the next day. I was talking about my 7PX and why I got it. Because I had a 4PX and the antenna broke in the little mast. Failsafe was not setup so the boat I was testing hit the shore when it lost range. And what he said was the 7PX and 10PX has a little antenna in the part that you turn up for range. And some have broke with a lot of use which will cause what your seeing. I turn my up for the day and it stays turned until the end of the day and I am ready to place back in the case. I see some racer turn it for every heat. And if your running a lot of boats thats a lot of turning.

 

[John Beardslee]

We had Futaba come and setup at the NAMBA Nats in Huntsville. Since they are in Madison next to Huntsville. They were there for support and repair. They fixed a lot of radio problems that racers were having. And did a wonderfull job. They done some testing with one of my boats with one of there GPS module. It worked great. I bought 4 of them the next day. I was talking about my 7PX and why I got it. Because I had a 4PX and the antenna broke in the little mast. Failsafe was not setup so the boat I was testing hit the shore when it lost range. And what he said was the 7PX and 10PX has a little antenna in the part that you turn up for range. And some have broke with a lot of use which will cause what your seeing. I turn my up for the day and it stays turned until the end of the day and I am ready to place back in the case. I see some racer turn it for every heat. And if your running a lot of boats thats a lot of turning.

Mark
Have done any range checks with out turning the antenna? Or just turning the whole transmitter? I have a transmitter covering that I’d have to cut in order to spin the antenna.
Thanks, John

 

[Rich Jones]

Easiest way to find out is to go around the switch and plugging the battery directly into the RX and if the problem goes away you have your culprit. I think bad switches account for a lot of totaled boats from radio failure I've seen over the years. You can't see the corrosion. One of the really great things about using waterproof radio gear is that the switch is eliminated.

Agree 100%

 

[Rich Jones]

Would be nice if you had a way to take the boat for a ride at that speed to see if it shuts down at that number or if vibration is still a possibility. You have a friend with a plane you could test that way & at same time enjoy the day in the air or fly to a restaurant some place.
Yes it's a far reach ,but nobody has found the answer yet. It's just safer in plane than car. Not sure about all the metal that could cause interference. The resonance could be the big answer, BUT is it possible to check the solder weld of reciever antenna. Have you bent or kinked the antenna, this will be a problem. Good hunting.

Having had one open, I know these receivers have 2 antennas. One is internal and goes to a little board on the underside of the top of the case. The other is the gray wire that you would run out of your box. (Sorry I just can’t get used to not running an antenna out of the boat). Both of these antennas plug into what resembles a mini coax connector on the main board. So they aren’t soldered to the board at all but wouldn’t hurt checking if they are plugged in or maybe a little loose. Be careful about just ripping the case open though as it would be easy to damage the internal antenna.

 

[Gary Staus]

My max speed on the fataba gps reads higher then the boat speed ,

 

[Grimracer]

Gary, How do you know this? What is giving you the other speed?

Grim

 

[Grimracer]

Mark
Have done any range checks with out turning the antenna? Or just turning the whole transmitter? I have a transmitter covering that I’d have to cut in order to spin the antenna.
Thanks, John

John, I have test data on that posted on here someplace.. let me see if I can find it

 

[Rich Jones]

Gary, How do you know this? What is giving you the other speed?

Grim

I think he is talking about how it gives a PEAK speed (like what you would get all out in a straightway) and then the actual speed at the time, ie you slow down to half throttle and it shows say 40 as your current speed. Whatever your peak is still shows up until you change models or turn off the radio.

 

[Grimracer]

Thank Rich, Gary, Make sure you have the latest firmware updated.

 

[Tom Foley]

Easiest way to find out is to go around the switch and plugging the battery directly into the RX and if the problem goes away you have your culprit. I think bad switches account for a lot of totaled boats from radio failure I've seen over the years. You can't see the corrosion. One of the really great things about using waterproof radio gear is that the switch is eliminated.

No , it was really the 75 Mghz that caused all the problems not switches or batteries.......

 

[Grimracer]

75 mhz was good..I really never had a bunch of issues with them.. but.. some years ago I use to travel around racing 1/8scale On-Road cars.. Futaba Magnum Senior truth be told..lol I was in South Dakota racing in the Midwest series.. good racing.. I was on the back straight the car had just shifted into 2nd.. and yep.. a guy with the matching Frequency turned on.. (I had the clip)... cost me a beautiful 100 dollar carbon chassis and the fun of packing up with a broken car and driving home with the cost of a few overnight stays and gas, and food.. and.. well you know.. that old chesnut.... (YES THEY HAD AN IMPOUND)

I HAVE NEVER had that happen again... not using 2.4..

END OF STORY... and PEROID.. that to me IS THE POWER OF 2.4...

Grim..

P.S. I was good too.. TQed just about every race I was in... but never won a main.. (no duration..(45min mains) story of my life!!!!LOL)

 

[Gary Staus]

Grim my radio has 7.0