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Author Topic: Weird throttle problem  (Read 3742 times)

KitS

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Re: Weird throttle problem
« Reply #25 on: August 20, 2021, 12:11:13 pm »

What I'm trying to do is run each ECU/motor setup from their own individual throttle.


My Planet T7 Tx has a twin-stick throttle in the left hand position, and I'm trying to match the stick position with the ECU/motor combination. The starboard pairing is the 'master' ECU in that its BEC is powering the Rx, and the starboard ECU has the red power lead disconnected from its RX cable.


Currently the port pairing works fine, and the starboard pairing exhibits the motor speed cut-off at around 85% of the throttle position.


If I swap the ECUs, both pairings work OK, full throttle in both directions, but the port motor runs much faster than the starboard.


This situation obtains whether I use one battery with a Y power lead, or with two batteries, one for each ECU/motor pairing.


It looks as if the signal from the starboard stick doesn't align with what the starboard ECU will accept, but the T7 doesn't have any EPA capability at all as far as I can see.

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Kit

C-3PO

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Re: Weird throttle problem
« Reply #26 on: August 20, 2021, 12:43:36 pm »

Try adjusting the "trim" adjustments - set the throttle ones to full down andf I presume full left for the second throttle channel  and then start from there, moving the "slower" running one to see if you can bring it up to the speed of the faster one

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C-3PO


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KitS

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Re: Weird throttle problem
« Reply #27 on: August 20, 2021, 01:01:49 pm »


The motor used to stop on full throw of the stick. I found by moving the trim to it's lowest setting, the motor spins up to full revs on full stick.


Try adjusting the "trim" adjustments - set the throttle ones to full down andf I presume full left for the second throttle channel  and then start from there, moving the "slower" running one to see if you can bring it up to the speed of the faster one




I tried moving the trims and it had some effect.  :-))


With the trim all the way back and with the ECU re-setup, I now have almost full throttle response on the starboard side, it only shuts down on the very last 'click' of the stick. I think I can live with that, I may even fit a stop bar so I don't go too far inadvertently.


In passing, the editor on here is junk! No matter what spacing I apply in my post, it does what it feels like!  {:-{
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Kit

C-3PO

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Re: Weird throttle problem
« Reply #28 on: August 20, 2021, 01:28:18 pm »

Excellent news - well done for persevering...

It's frustrating not being able to see the "value" in ms of the individual RX channel outputs.

Maybe I should dust off an old project....

https://youtu.be/f9C_GG0x0Fc

Regards
C-3PO
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HMS Invisible

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Re: Weird throttle problem
« Reply #29 on: August 20, 2021, 01:41:03 pm »

Excellent news - well done for persevering...

It's frustrating not being able to see the "value" in ms of the individual RX channel outputs.

Maybe I should dust off an old project....

https://youtu.be/f9C_GG0x0Fc

Regards
C-3PO
A receiver health check and comparitive pwm measurement is possible, with precision, by a voltmeter.
I still think it is worthwhile taking a current measurement.
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Skrotiz

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Re: Weird throttle problem
« Reply #30 on: August 20, 2021, 04:41:46 pm »

Had to search for twin stick conversions, might have to get me something like that for my next twin motor build.


Do you use channel3 for one of the esc?
If so, is it possible for you to connect your twin stick to another channel than 3?
The problem might be that channel3(I presume this is the original throttle channel) have more throw(bigger pwm difference between lowest and highest) and thats what makes your esc cutout at 85% throttle.


Another option if you don't want to hack into the radio is to use you're other stick for testing with one esc up/down and the other left/right to se if the problem dissapears when using for example channel1&2.


When I run in to this kind of trouble I often connect two identical servos instead of the ESC:s to be able to see whats happening and theres always the option to hook it up to the oscilloscope but thats not an option for you.


Measuring pwm value, as already said, can be done with a multimeter.
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HMS Invisible

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Re: Weird throttle problem
« Reply #31 on: August 20, 2021, 04:49:52 pm »

Can anyone with this radio say if there is a hardware adjustment for pwm on all Tx channels?
Does someone on youtube open one up to show the guts?
For some, changing or adding resistors is no problem but turning a preset would be handy.


Edit:
No dual rate channels like this has? https://fccid.io/XUN015495/User-Manual/user-Manual-1365882
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C-3PO

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Re: Weird throttle problem
« Reply #32 on: August 20, 2021, 05:13:20 pm »

The inside of a Planet radio I saw - all surface mount components - No hardware pwm adjustment

A very simple main board based around an Atmel processor and a seperate RF board - very simple - not a lot to it - circuit board soldering was shocking!



C-3PO
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Martin (Admin)

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Re: Weird throttle problem
« Reply #33 on: August 20, 2021, 05:21:02 pm »


In passing, the editor on here is junk! No matter what spacing I apply in my post, it does what it feels like!  {:-{


Have some respect, it's >20 years old!    {-)

 NB: Try the WYSIWYG / BB, whichever you're not using!

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HMS Invisible

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Re: Weird throttle problem
« Reply #34 on: August 20, 2021, 05:52:57 pm »

The inside of a Planet radio I saw - all surface mount components - No hardware pwm adjustment

A very simple main board based around an Atmel processor and a seperate RF board - very simple - not a lot to it - circuit board soldering was shocking!



C-3PO

Thankyou!
I think that leaves the options:
* a stop bar
* solder a resistor
* mechanical adjustment if there is rotary pots in the twin stick.
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KitS

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Re: Weird throttle problem
« Reply #35 on: August 20, 2021, 05:55:59 pm »

As I said before, there are no adjustments inside the Tx apart from 4 switches to change from Mode 1 to Mode 2 for flyers.


The twin-stick throttle looks like the levers from a Robbe F-14 Navy with the control pots from the original LH joystick grafted onto them. They're plugged into a sub-board up near the aerial, which in turn has a multi-cable connection to the main board near the bottom of the case. The cables aren't long enough to fit any socket other than the one they're currently fitted to.


Obviously a major internal re-wiring of the Tx would be possible, but I gave up that sort of stuff around the time I re-wired my Skyleader 6 ch set to work separate spoilers on a sailplane........


So far the stop bar works pretty well, but I'll see how it goes on the water tomorrow.


The dual rate switches and pots only affect the aileron and elevator functions on the T7.
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Kit

HMS Invisible

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Re: Weird throttle problem
« Reply #36 on: August 20, 2021, 06:47:20 pm »

... the control pots from the original LH joystick grafted onto them...

I don't know the nuisance factor involved but I'm sure that means loosening & rotating the pot shaft beyond the present mechanical trim setting is possible.
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malcolmfrary

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Re: Weird throttle problem
« Reply #37 on: August 20, 2021, 08:55:40 pm »

What I'm trying to do is run each ECU/motor setup from their own individual throttle.


My Planet T7 Tx has a twin-stick throttle in the left hand position, and I'm trying to match the stick position with the ECU/motor combination. The starboard pairing is the 'master' ECU in that its BEC is powering the Rx, and the starboard ECU has the red power lead disconnected from its RX cable.


Currently the port pairing works fine, and the starboard pairing exhibits the motor speed cut-off at around 85% of the throttle position.


If I swap the ECUs, both pairings work OK, full throttle in both directions, but the port motor runs much faster than the starboard.


This situation obtains whether I use one battery with a Y power lead, or with two batteries, one for each ECU/motor pairing.


It looks as if the signal from the starboard stick doesn't align with what the starboard ECU will accept, but the T7 doesn't have any EPA capability at all as far as I can see.
Just as a test, running both ESCs controlled via a Y lead will ensure that both get the same signal.  Any difference in motor speed will then be something to do with the motor.  If the problem ceases, then one channel is getting different information, the difference probably originating in the transmitter.  Plugging the Y lead into the other ESC channel on the receiver might show a difference, which should be on both motors.
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unbuiltnautilus

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Re: Weird throttle problem
« Reply #38 on: August 20, 2021, 09:22:34 pm »

Just a quick observation, then I am out of here!! The Vipers do suffer from an issue with mixers, where beyond a certain point of signal input ( forgive my lack of technical, it's been a long day! ) from neutral they will stop dead. The Tio controllers do not, so option 1, change for Tios.
If this twin stick unit is a mash up using the original pots and the pots were not quite correctly aligned for the channels deadband, at extremes this may cause the drop out, even if you follow the correct set up procedure.  old Acoms Txs were prone to suffer from 'pot wander' and would need delicate adjustment with a big pair of pliers to get everything back where it needed to be! Also, I note that there was a dual rate switch that reduces the aileron/elevator channel movements. Pretty sure this is the right hand stick on a mode 2 set, but, and I am not sure if memory serves me well, but there may have been a mode 1 version of the T7 available. If that is what you have, that could contribute to your problems as either aileron or elevator could be part of the left sticks pots. Best bet, set the dual rate function to 0% or 100%, or just turn off the dual rate function.


Anyway, good luck with the minefield of info that I have just contributed more to :-))
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unbuiltnautilus

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Re: Weird throttle problem
« Reply #39 on: August 20, 2021, 09:24:28 pm »

And do you know what, you pretty much nailed what I just typed in your first post :o
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KitS

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Re: Weird throttle problem
« Reply #40 on: August 20, 2021, 10:33:13 pm »


@unbuiltnautilus,

I've listened politely and nodded approvingly, thanks.   :-) :-))
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Kit

unbuiltnautilus

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Re: Weird throttle problem
« Reply #41 on: August 21, 2021, 07:58:49 am »

What more could I ask?
 :-) :-))
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C-3PO

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Re: Weird throttle problem
« Reply #42 on: August 21, 2021, 11:03:05 am »

Internals of Planet T5 - I would imagine the T7 would be very similar (more than likely the same board with fewer external control surface connections)

















Regards
C-3PO


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KitS

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Re: Weird throttle problem
« Reply #43 on: August 21, 2021, 05:20:00 pm »

Quite similar, yes.  :-))


The RF section is larger on the T7, with one BIG can thing in the middle, there's only 4 mode change switches and the sticks are all plugged into a separate board that's up near the aerial.


But it's obviously from the same manufacturer, and totally free of any pots to adjust.
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HMS Invisible

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Re: Weird throttle problem
« Reply #44 on: August 21, 2021, 05:56:15 pm »

You should be able to loosen a twin stick pot and adjust slightly beyond the mechanical trim's present limit.
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KitS

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Re: Weird throttle problem
« Reply #45 on: August 21, 2021, 06:00:02 pm »

One would hope so, yes.


I've not got that far yet, but I'll try once it stops raining and I can try the boat on the water.  :((
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KitS

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Re: Weird throttle problem
« Reply #46 on: August 21, 2021, 09:57:21 pm »

Having got fed up with the weather I stripped the twin throttle stick down, and it's not adjustable.


The pot shafts have flats on one side and the throttle arms have moulded cutouts that align exactly with those flats.


I took a pic of the situation with my phone, but as usual it doesn't want to transfer anything to my laptop, so that's that.
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HMS Invisible

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Re: Weird throttle problem
« Reply #47 on: August 21, 2021, 10:30:09 pm »

Having got fed up with the weather I stripped the twin throttle stick down, and it's not adjustable.


The pot shafts have flats on one side and the throttle arms have moulded cutouts that align exactly with those flats.


I took a pic of the situation with my phone, but as usual it doesn't want to transfer anything to my laptop, so that's that.
This arrangement was already apparent in C-3PO's photos but it is just abs or similar plastic. A needle file or soldering iron would make short work of it.
This was just a mechanical alternative to soldering.

A series resistance into black or red pot feed wires will shift neutral voltage & timing one way and reduce span if goes into the brown (centre of pot) connection.
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malcolmfrary

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Re: Weird throttle problem
« Reply #48 on: August 22, 2021, 09:33:16 am »

Most joystick pots are a basic variable resistor, and mount using the threaded collar shown arrowed in the picture.  Mechanical trims work by rotating the pot body, this basic positioning can be rearranged by very careful stripping and reassembly with the desired offset.
If the 2nd throttle stick is mounted as a mirror of the first, it could be the case that its wipers no longer cover the required bit of track, and thus give different results.  Checking the voltages at the wiper connections and comparing them at various positions might give useful information.
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KitS

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Re: Weird throttle problem
« Reply #49 on: August 22, 2021, 04:08:41 pm »

Well it floats, and it goes quite well, specially on 9.6V, but it would go even better with both props............  {:-{


One of them, the troublesome starboard side, fell off after about a minute of running, and it's at the bottom of the lake now.


But the limit bar on the throttles worked quite well during the short time that it mattered.


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Kit
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