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Noob seeking help w/ motor/ESC/RX/TX problem - can't throttle to max

jddj

New member
#1
Hi, I'm just getting into R/C, and am building a "towel" Delta-wing flyer, one mistake at a time.

I've got fully charged lipos, an ESC that seems to be responding correctly, a receiver that appears to be working, and a motor that can maintain rpm only with the TX shut off, and only for a second. I can't get the motor to spin up to takeoff power. Motor and ESC were purchased as a bundle, so I think the ESC (18A, no-name) is appropriate for the motor (370 size B2208, 1800KV).

The ESC is programmed for 3 cell lipos, no prop brake (verified). The TX/RX pair is an HK-t6a.

Here's a video of what happens:

https://youtu.be/NzkukIBVX4s

I'd be happy to Google for info myself, but for a change, I can't figure out the right description to make an efficient query. What do I call this behavior? Is it a common thing?

Hope you can make me smarter. Any thoughts are appreciated.
 
#2
I'll try to help. First don't power up the RX,ESC without the radio being on, Radio on first then the Rx!
Now you most likely need to calibrate the ESC. Here is how.
*******REMOVE THE PROP********! For Safety!
1. Turn on the radio
2. Adjust the throttle trim all the way down.
3. Move the throttle stick to max throttle
4. Plug in the ESC, wait for the single beep, should happen after a couple seconds.
5. Move the throttle stick down to the min. throttle position and wait for a beep. Some ESC's won't beep but just wait about 10 seconds and try the throttle.
Now it should throttle correctly, If it doesn't try again.
I have seen and had an ESC that was programed for helicopter operation and that did some weird throttle responses hopefully that is not the case here. I wound up buying a special programming card to get that ESC to work on an airplane.
OH and when you shut down the plane, ESC,Rx first, then the radio!
Hope this gets you going.
Gerald Cook "ViperTech"
 

quorneng

Well-known member
#3
Not sure why the throttle is not working correctly but following ViperTechs advice should cure it.
The fact that the ESC goes to full power when you switch off the Tx suggests it is a Tx or radio related problem.
The fact that is cuts after a second or two after switching off the Tx is a normal ESC 'fail safe' resulting from signal loss.
 

jddj

New member
#4
I'll try to help. First don't power up the RX,ESC without the radio being on, Radio on first then the Rx!
Now you most likely need to calibrate the ESC. Here is how...
Thanks for the ideas, but no fix so far. Tried it a couple times as you suggested, with turn-on order as you suggested. Same result.

I think I'll have a look at reprogramming the TX next - I believe I flashed new programming between the time things were working and the time this situation started.

Have been working under the suspicion that I'd damaged something, or that I was hitting the LiPo low-voltage cutoff when wide open. The latter is certainly not true. Still not sure I haven't damaged something.

Open to any other ideas, thanks.
 

jddj

New member
#7
jddj
Did try to alter the Tx programming or do you think it was an accident.
I set up the elavon servo direction, elavon mixing, throttle cut off switch and dual-rate switch (granny switch). All these appear to function well. Didn't do anything intentional that would mess up the throttle in the way seen in the video. Will double check it's not set up for a quad, nothing else mixing to ch. 3, etc.

Maybe just got a bad flash - one-off bad juju. Let me see.
 

jddj

New member
#8
Maybe just got a bad flash - one-off bad juju. Let me see.
Well, that didn't pan out. Setup was exactly as I'd configured it, and showed no problems.

Re-ran the stick calibration, worked as expected. Saved it back to the TX, same problem upon trying again. Just like the video.

I metered the motor leads, across each pair in the 3 windings (if you get what I mean: 1-2, 2-3, 3-1), and they came in acceptably close to each other.

The ESC on the other hand came out 55k, 55k, 110k (which the astute will note is double the 55k). Can't decide whether this is a good reading or bad - just poking around with it ATM.

Think I'm going to look for a new cheap ESC or ESC/Motor combo.
 

quorneng

Well-known member
#9
jddj
Yes the only sure way of testing anyhting is to put it on something that you know works.
I always have a spare ESC and motor on the bench.
A servo tester is also a useful addition as it can also be used to drive an ESC and motor without using any radio link at all.
ESCtest.JPG
Its about as simple as it gets!
 

Bricks

Well-known member
#10
Are you powering on the receiver before powering on the transmitter? I had one ESC that this was a no no it would act similar to yours.
 
#11
jddj
Yes the only sure way of testing anyhting is to put it on something that you know works.
I always have a spare ESC and motor on the bench.
A servo tester is also a useful addition as it can also be used to drive an ESC and motor without using any radio link at all.
View attachment 81244
Its about as simple as it gets!
Eliminating as much as you can like in this quote is the way to go. Keep it simple.

Not to change the subject but where did you get your insulated connectors for your example?
 
#12
Not to change the subject but where did you get your insulated connectors for your example?
Mine from the video? The motor and ESC came as a (cheap) bundle, and they were already heat-shrinked. I've got a bunch of heat-shrink and a heat-gun, so could've done the same.

Back on-topic: I cut the heat-shrink off the ESC and poked at a bunch of stuff with a spudger and while I haven't narrowed it down completely, I think there's something intermittent going on with the ESC board - possible I loosened the heat sink when I velcroed the package down or something.

New motor and ESC on the way anyway...

Thanks all for the good advices!
 
#14
What brand and model ESC? Does it have programmable timing?
It's a no-name (wrapped in yellow shrink-wrap), and has only the bare bones: LiPo/Nickel and baking, as far as I can tell. No obvious way to set timing.

Really, because I can fix it/break it by yanking around the ESC (I've lately discovered), it's probably ESC or wiring. Will know when a new ESC arrives soon.

Thanks for weighing in.
 

Hai-Lee

Old and Bold RC PILOT
#15
Had a plane with a similar , Not exactly the same, problem. Eventually we fitted the ESC into a different channel and found it performed perfectly in the new channel. A further look into his programming found that he had previous had a differential thrust setup on the model slot he was now using. After a reset of the model slot back to factory and refitting the ESC back to channel 3 all worked as was required.
 
#17
Epilogue

Just wanted to close the thread with the resolution: yes, definitely a bad ESC. Replaced it with a 30A UBEC and same motor and wiring are working well now.

Thanks all for the input.