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Post by johnny1 on Oct 9, 2012 3:01:57 GMT 1
I just did a rebuild of everything on my supercub from the firewall forward. Did lots of patching on the fuselage and wings also. When I plugged the battery in (making sure the Spektrum DX4e transmitter was turned OFF and the throttle stick all the way down), the propellor came on full blast. It is as if the controller (ESC?) got stuck in the ON position somehow. Do I have a short circuit? Not sure how to troubleshoot this. Thanks!
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Post by flydiver on Oct 9, 2012 4:07:46 GMT 1
NEVER, no matter what any other Spektrum owner says, plug in a receiver with the TX off!!!!!!
It's a poor habit at best and potentially dangerous at worst.
When done flying, unplug the battery FIRST, only then turn off the TX.
A powered RX with no input from the TX can do strange things, like you just experienced. Spektrum is not supposed to...but it occasionally will. Yeah, It's not perfect like a lot of people seem to think. (If the manual says it's OK, ignore the stupid manual).
Now, try it that way. TAKE THE PROP OFF FIRST!!!!!
Report back.
It would seem like you had a nasty crash. That OFTEN takes out the ESC and will produce the same symptoms.
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Post by renard80 on Oct 9, 2012 20:49:16 GMT 1
Yep, like the man says - it was always drummed into me: Transmitter On FIRST and Off LAST.  (It may seem unnatural to connect the battery after switching on the Tx, but that's the correct sequence.) |
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Post by brakallie1 on Oct 11, 2012 3:07:44 GMT 1
Can this also cause the motor to start up (upon request) and then just start?
Thks,
brakallie1
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Post by flydiver on Oct 11, 2012 3:59:11 GMT 1
Try that again?
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Post by johnny1 on Oct 11, 2012 4:26:13 GMT 1
Well, I tried the suggestion (transmitter on first, pull throttle lever all the way toward me, plug in). Same thing happens - prop runs full blast. I suspect I messed up the electronics in the crash, and now it is stuck "on". The servos and tail look good. Battery compartment is fine. I assume that the piece I need to replace is the Receiver/ESC unit (Hobbyzone part number HBZ7357). I believe then I will need to re-bind the transmitter to the new receiver.
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Post by flydiver on Oct 11, 2012 4:45:25 GMT 1
You got it.
In a crash, often even in a tip-over, people forget to IMMEDIATELY turn off the throttle.
A stuck motor with power in it is a short circuit. The ESC is the victim-it fries. This will happen with ANY stalled motor. The Cub ESC is kinda lame and very prone to this. It's also at the hands of newbies that don't know the problem of a stalled motor.
Make it a habit- when you kill your plane > kill the power.
Since the ESC/RX is probably ~$50 with shipping, NOW is the time to consider an upgrade to brushless and separate components. More complicated, somewhat more expensive, and a better deal in the long run. This is just about the most common mod to a Cub besides, tires, tape, and glue. Lots of suggestions in the forum.
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Post by johnny1 on Oct 22, 2012 4:41:40 GMT 1
I replaced the RX/ESC unit, rebound, and now it works OK. The "on full blast" problem has disappeared. So, it appears that I did need to make the replacement.
I did the binding process as explained in the video and book, and that appeared to work.
One concern - although the TX is communicating just find with the plane, the LED light on the RX/ESC is blinking slowly (not on constant). I will recharge the battery. Hopefully, it just means a low charge. Otherwise, I don't know what this means.
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Post by johnny1 on Oct 24, 2012 3:08:44 GMT 1
I solved my concern. The blinking was caused by me not firmly connecting the battery. It had a weak connection, and probably disconnected once before I firmly pushed the plug together. If instead, I really push it firmly in just once, the light shines steady. Of course, TX on first, and off last.
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