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Old 07-15-2007, 03:41 PM   #1
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Default Problem with brand new 3PKS/FASST

I am having a problem with my brand new 3PKS w/ FASST system. I'm planning on calling Futaba tomorrow, but in the meantime i thought i might see if anyone has any ideas. The issue is that i am randomly losing the signal from the transmitter and going into failsafe mode. At first i thought it was a problem with my receiver switch, and then thought it was the battery/rx power, but have ruled both of those out now. When it happens the light on the receiver goes red. It appears that i can turn off both the tx and rx, and then turn them on again and it will work again until the next occurrence.

I am running the antenna inside the body but have not modified the length, and i also had the tx antenna horizontal and down and not extended vertically. Could this possibly be the cause? The track is very small and the issue was occurring at distances of 30-40 ft. I'm sure it's better for range to have the antenna up, but i'm having trouble imaging that would cause this problem at such short range.

The only other thing i've noticed is that the receiver was quite hot after running. Is it possible that excess heat could cause the problem?

Any feedback would be appreciated, thanks!
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Old 07-15-2007, 04:35 PM   #2
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What car?
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Old 07-15-2007, 05:28 PM   #3
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it's in an xray xb8ec. happened 3 times today at the track and ended up costing me the race. I just ran it in the street outside my house for a full tank and it worked fine.
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Old 07-15-2007, 05:53 PM   #4
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i wanted to add that i am running in HRS mode.
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Old 07-15-2007, 06:32 PM   #5
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If you're running digital servos, it could be that you're causing a voltage dip, which is causing the failsafe to kick in. What you could try, is putting the car up on a stand with the wheels off the ground and the engine off. Then go wild on the throttle and steering for 5 minutes to see if you can induce the problem.
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Old 07-15-2007, 06:48 PM   #6
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interesting, ill try it but if the voltage failsafe activates, would it then stay in failsafe mode until the receiver and transmitter are reset? I also wonder if the voltage failsafe causes the status light on the receiver to go red, since red is supposed to indicate "no signal reception".
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Old 07-15-2007, 07:00 PM   #7
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Quote:
Originally Posted by chris3g View Post
interesting, ill try it but if the voltage failsafe activates, would it then stay in failsafe mode until the receiver and transmitter are reset? I also wonder if the voltage failsafe causes the status light on the receiver to go red, since red is supposed to indicate "no signal reception".
Sorry, don't know the answer to these questions.
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Old 07-15-2007, 07:11 PM   #8
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what would be the best way to get a measurement of the voltage output of the battery while it is in use? it would definitely be helpful to be able to watch is happening as the servos are operating.
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Old 07-15-2007, 10:21 PM   #9
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ok well i have a voltmeter hooked up to my battery lead with everything connected, the battery is reading 6.2v with the servos at neutral and ~ 5.8 - 5.9v when going nuts on both the throttle and steering servos. This is a pretty long way off from the 4.75v necessary to kick on the failsafe, but it's also with no load - the radio tray is out of the car right now. I wonder how much of a difference if any it makes with the servos actually pushing the wheels and brake. For now i'm going to let the battery run down so i can see what actually happens when the voltage failsafe kicks in. And so far i've also been unable to recreate the issue.

i'm all ready to order a new lipo/voltage regulator setup but i'd hate to do that and then find out there was something wrong with the radio after all. Any other ideas?
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Old 07-15-2007, 10:58 PM   #10
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in case anyone is reading, i have ruled out voltage failsafe as a cause of the problem. Using the discharge feature on my ice charger i was able to drop the voltage to failsafe range while operating the servos, when this occurs the throttle servo goes into failsafe position but the steering servo remains operable and the light on the receiver remains green, neither of which happen when my problem occurs.

thank you for the suggestions btw, at least i was able to rule that out.
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Old 07-15-2007, 11:20 PM   #11
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Running analog servos in HRS mode can cause such a thing.
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Old 07-15-2007, 11:21 PM   #12
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thanks, but i am running 2 digital servos - S9451 throttle and S9351 steering
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Old 07-16-2007, 05:51 AM   #13
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sounds like a bad rec or tran module, happens, we have seen similar things with all brands of dsm, just a occasional bad one that is exta sensative while racing. also a note as the servos heat up ie motors get warm during a race, they pull more amps for the same movement. so you can still get a failsafe action. we always run a cap in the gas cars with dsm.
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Old 07-16-2007, 03:49 PM   #14
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futaba wants me to send it in. 2 week turnaround, and apparently i pay shipping both ways. It's two weeks old, nice
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Old 08-06-2007, 07:12 PM   #15
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Thought i'd update this in case anyone in the future has a similar issue and finds this with a search. Sent everything in to Futaba, they tested and found the module and/or the receiver to be defective and replaced them both. The transmitter itself was fine and was returned to me. Service was reasonably good - i wish it had been quicker but once they got around to looking at my equipment they did get the replacements out promptly.
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