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Issue with servo Y-cable

FDS

Well-known member
#21
Have you tried a different ESC? The BEC in that one might be damaged?
If you are having the same problems with multiple ESC’s then try a different RX?
Also what type of servos do you have? A high refresh rate digital metal gear servo can draw significant amounts of power vs a basic analogue one. You could easily be getting brown out on 3 larger digital servos with a 3a bec.
I am not a fan of the Simonk type ESC, they are designed for quads and usually need reprogramming to be optimised for fixed wing, for example having no voltage protection (cuts throttle if voltage falls below 3.6v/cell) is bad in quads but useful in fixed wing.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#22
It may very well be a power issue as I have had similar in the past but without a decent picture of your setup I must go through the setup with you gathering clues as we go.

Are you running a dual motor setup? Is that setup using a "Y" harness or 2 separate channels? Do you have a spare ESC, (any current range will suffice because we will not be connecting any motors until the servos and Rx work well together)?

Have fun!
 
#23
Have you tried a different ESC? The BEC in that one might be damaged?
If you are having the same problems with multiple ESC’s then try a different RX?
Also what type of servos do you have? A high refresh rate digital metal gear servo can draw significant amounts of power vs a basic analogue one. You could easily be getting brown out on 3 larger digital servos with a 3a bec.
I am not a fan of the Simonk type ESC, they are designed for quads and usually need reprogramming to be optimised for fixed wing, for example having no voltage protection (cuts throttle if voltage falls below 3.6v/cell) is bad in quads but useful in fixed wing.
I tried a different ESC and reciever, and it mostly fixed the problem. Since I only have two of the same receivers, and the only thing that changed it was a different ESC, My issue now is that I don't have two of the same ones. I only have two Simon ESCs. It seems more and more like I just need to buy new ones. Do you have any recommendations for decent 30a ESCs that won't give me this issue? Ideally I'd like to pay less than 10 bucks per ESC.
It may very well be a power issue as I have had similar in the past but without a decent picture of your setup I must go through the setup with you gathering clues as we go.

Are you running a dual motor setup? Is that setup using a "Y" harness or 2 separate channels? Do you have a spare ESC, (any current range will suffice because we will not be connecting any motors until the servos and Rx work well together)?

Have fun!
I've done my best to lay out my current setup. I do have a dual motor setup, as I mentioned earlier, its connected with a Y cable, and mixed so that it uses differential thrust.

15516301208441121760791463694292.jpg 15516301767178078211312333113651.jpg Channel 1 is the aileron y cable, channel 2 is the elevator servo, channel 3 is the ESC supplying power to the reciever, and channel 6 is the second ESC with a disconnected positive lead so the Receiver doesn't get power from both ESCs
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#24
Your basic setup is correct and should work well. The only thing I cannot comment upon is the Rx. I have all three types of the iA6 Rx but I haven't used the 8.4V version as yet and I cannot find where I have stored them!

Does the Rx ever get warm/hot when the problem occurs. I ask because I do not know if the Rx itself has a voltage regulator built in! Perhaps someone else could step in to advise if they have experience with that exact model Rx.

If you have a 2S battery you could try disconnecting the red lead from both ESCs and power the Rx using the 2S battery in the "B/VCC" port.

It could also be a simple High resistance connection somewhere in the Rx which causes the issue!.

If the issue occurs, try unplugging one of the servos, (without powering down and see if it recovers by itself!

Let me know what you try and any results!

have fun!
 
#25
Your basic setup is correct and should work well. The only thing I cannot comment upon is the Rx. I have all three types of the iA6 Rx but I haven't used the 8.4V version as yet and I cannot find where I have stored them!

Does the Rx ever get warm/hot when the problem occurs. I ask because I do not know if the Rx itself has a voltage regulator built in! Perhaps someone else could step in to advise if they have experience with that exact model Rx.

If you have a 2S battery you could try disconnecting the red lead from both ESCs and power the Rx using the 2S battery in the "B/VCC" port.

It could also be a simple High resistance connection somewhere in the Rx which causes the issue!.

If the issue occurs, try unplugging one of the servos, (without powering down and see if it recovers by itself!

Let me know what you try and any results!

have fun!
The reciever never gets warm, but if I leave the servoes and they lock, the ESC supplying power to the receiver does get hot, but not the receiver itself. Unplugging one of the servos does reset them, but doesn't fix the issue. As for the 2 cell battery, I don't understand what you mean by plugging it into the b/vcc port, as it has no service lead, and I don't want to jam the charging cable into it and risk bending the leads. This is what the cable looks like:
15516339088548122219459065980437.jpg
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#26
I do know the various plugs for the batteries but you can also get a lead for direct connection to a Rx for lower voltage battery connections or even make one from a dead servo and a battery power connector. For aircraft that do not use an electric motor ordinary Rxs would still require a voltage regulator to power the Rx and servos, (A UBEC). The Rx you have there is one for direct connection to batteries, (Up to 8.4v or 2S), rather than using a separate voltage regulator.

As I said previously I have no experience using the HV Rx in a motor driven application where the ESC is used to power the Rx.

Have you tried to change which of the ESCs powers the Rx in your setup?

When the ESC gets hot do any of the servos get warm? DO you have access to and know how to use a multimeter?

Have fun!
 

Keno

Active member
#27
I read over what going on. I have one question and I may have missed the post on this, does your transmitter have a monitor feature? If It does it is a great aid when program channel mixing you can see what happen before you plug in your servos. Only a question you guy go on with your troubleshooting. All have a great day and sure hope you solve your problems.
 

FDS

Well-known member
#28
The heat in the ESC is caused by the servos drawing max stall current as the motor keeps the arm at its furthest position. If it browns out at that point the servo may get locked there because the ESC heats up too much to power the RX enough to re set the servo position.
When they are centred the motor is off, with varying motor load up to full stall at maximum deflection. That’s why flaps are power hungry, you require the servo to fully extend to hold them in place.
I use the Hobbyking 30A or Skywalker 30A esc’s, both are good for fixed wing. They usually come pre set with the battery safety setting on and can be programmed if required.
To a degree you get what you pay for with ESC’s, I would rather spend a bit more for reliability than rely on lowest possible cost components.
 
#29
I do know the various plugs for the batteries but you can also get a lead for direct connection to a Rx for lower voltage battery connections or even make one from a dead servo and a battery power connector. For aircraft that do not use an electric motor ordinary Rxs would still require a voltage regulator to power the Rx and servos, (A UBEC). The Rx you have there is one for direct connection to batteries, (Up to 8.4v or 2S), rather than using a separate voltage regulator.

As I said previously I have no experience using the HV Rx in a motor driven application where the ESC is used to power the Rx.

Have you tried to change which of the ESCs powers the Rx in your setup?

When the ESC gets hot do any of the servos get warm? DO you have access to and know how to use a multimeter?

Have fun!
I do know the various plugs for the batteries but you can also get a lead for direct connection to a Rx for lower voltage battery connections or even make one from a dead servo and a battery power connector. For aircraft that do not use an electric motor ordinary Rxs would still require a voltage regulator to power the Rx and servos, (A UBEC). The Rx you have there is one for direct connection to batteries, (Up to 8.4v or 2S), rather than using a separate voltage regulator.

As I said previously I have no experience using the HV Rx in a motor driven application where the ESC is used to power the Rx.

Have you tried to change which of the ESCs powers the Rx in your setup?

When the ESC gets hot do any of the servos get warm? DO you have access to and know how to use a multimeter?

Have fun!
Although trying the ESC didn't fix the problem, plugging the other battery in did. Although not ideal, I might be able to plug a small 2 cell 1100 mah battery into the b/vcc port. It weighs about 50 grams, but as of right now it the only thing that works. You were right about the receiver not getting enough power. Would a setup involving both batteries work, or am I better off removing the positive lead from both ESCs? I haven't noticed the servos getting warm, however I'm sure if I left them in their locked state, they would. As for a Multimeter, I do have one and can use it, but it's not a super great one.
 
#30
The heat in the ESC is caused by the servos drawing max stall current as the motor keeps the arm at its furthest position. If it browns out at that point the servo may get locked there because the ESC heats up too much to power the RX enough to re set the servo position.
When they are centred the motor is off, with varying motor load up to full stall at maximum deflection. That’s why flaps are power hungry, you require the servo to fully extend to hold them in place.
I use the Hobbyking 30A or Skywalker 30A esc’s, both are good for fixed wing. They usually come pre set with the battery safety setting on and can be programmed if required.
To a degree you get what you pay for with ESC’s, I would rather spend a bit more for reliability than rely on lowest possible cost components.
I'll look into the ESCs, and appreciate the suggestions. For now I appear to have found a temporary solution, involving a separate battery to power the reciever. I understand the risk of buying cheap equipment, especially electronics, but I hoped they would be sufficient. Clearly, I was wrong
 

FDS

Well-known member
#31
Glad you are on the way to a solution. There are different types of voltage regulator, linear and switching. A linear bec is the most common, partly due to its simplicity and low noise. The heat generated and the poor efficiency can cause the rated output to be lower than the actual output.
I would also investigate your primary battery, if it’s past it’s best or not sufficiently powerful then it might be part of the problem. Check the cell individual voltages and make sure the overall voltage isn’t sagging under the motir load, as that will affect the power available for servos as well as battery life.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#32
Although trying the ESC didn't fix the problem, plugging the other battery in did. Although not ideal, I might be able to plug a small 2 cell 1100 mah battery into the b/vcc port. It weighs about 50 grams, but as of right now it the only thing that works. You were right about the receiver not getting enough power. Would a setup involving both batteries work, or am I better off removing the positive lead from both ESCs? I haven't noticed the servos getting warm, however I'm sure if I left them in their locked state, they would. As for a Multimeter, I do have one and can use it, but it's not a super great one.
OK my suspicion of the Rx arose from the fact that it has the ability to drive the servos directly from a 8.4 voltage source. In my mind, (somewhat small at times), in order to drive ordinary servos a form of regulator would need to be part of the Rx. I searched the I/net for any info but so far have drawn a blank.

Anyway in order to make the Rx fail safe and to protect it there would logically be some form of over voltage protection. My fears were that it would be a shunt or crowbar protection for rapid response and as such it is capable of pulling quite a few amps from the 5Volt rail if necessary. This action would drag the rail down and overheat the BEC in the ESC. It could even be triggered by a noisy servo. (one that generates voltage spikes).

If using 2 batteries you would definitely need to remove both red wires from the ESCs.

Now for the lightest possible solution.

Remove the 5 volt leads from both of the ESC connectors.

Rather that using an extra battery you can fit a UBEC directly into the B/VCC and connect the UBEC to the existing battery, (a little soldering may be required at the battery lead connection on one of the BECs,

OR

You can make up a "Reverse" "Y" Harness out of either 2 extension leads or an extension lead and the lead from a dead/damaged servo.

By reverse I mean a single male plug, (the one that a servo will plug into), and two sockets, (same as the standard servo plug).

Now reconnect the red lead on one of the ESCs and plug the ESC into the "Reverse" "Y" harness.

One one of the "Reverse" "Y" harness remaining leads remove the red wire, (this one plugs into the selected throttle channel).

On the remaining "Reverse" "Y" harness socket remove the WHITE wire. This lead plugs into the B/VCC port of the Rx. This should allow the ESC to provide power, (5V) to the 4.0 - 8.4V input whilst isolating the 5V from reverse voltage feeding of the Rx.

Before soldering and modifying try removing a white wire from an ESC and plug it into the B/VCC port whilst at the same time ensuring there is not red wire connection to the output Rx ports from any other ESC. If it works then the "Reverse" "Y" Harness will work for you and that Rx.

Let me know what you find!

have fun
 
#33
Glad you are on the way to a solution. There are different types of voltage regulator, linear and switching. A linear bec is the most common, partly due to its simplicity and low noise. The heat generated and the poor efficiency can cause the rated output to be lower than the actual output.
I would also investigate your primary battery, if it’s past it’s best or not sufficiently powerful then it might be part of the problem. Check the cell individual voltages and make sure the overall voltage isn’t sagging under the motir load, as that will affect the power available for servos as well as battery life.
The batteries I'm using are brand new, and run at or above the 11.1 volts they're rated for. As for the built in BEC, I have no idea how to check it, or frankly where it even is on the ESC. I'm relatively new to rc airplanes. Until recently I would usually use rc cars, with occasional cheap drones and coaxial helicopters. This is the second rc airplane I've built, and much more complicated than the elavon one I built awhile ago.
 

PsyBorg

Wake up! Time to fly!
Mentor
#34
Ok caught up with all this again.

Lets get simple and check one thing everyone including myself has over looked.

Is the y cable pinned out properly. Are the connectors wired in the proper order on all 3 ends?

One mixed up wire would surely cause severe wonkiness. Wouldnt be the first cable to escape manufacturing that is miss wired.
 
#35
OK my suspicion of the Rx arose from the fact that it has the ability to drive the servos directly from a 8.4 voltage source. In my mind, (somewhat small at times), in order to drive ordinary servos a form of regulator would need to be part of the Rx. I searched the I/net for any info but so far have drawn a blank.

Anyway in order to make the Rx fail safe and to protect it there would logically be some form of over voltage protection. My fears were that it would be a shunt or crowbar protection for rapid response and as such it is capable of pulling quite a few amps from the 5Volt rail if necessary. This action would drag the rail down and overheat the BEC in the ESC. It could even be triggered by a noisy servo. (one that generates voltage spikes).

If using 2 batteries you would definitely need to remove both red wires from the ESCs.

Now for the lightest possible solution.

Remove the 5 volt leads from both of the ESC connectors.

Rather that using an extra battery you can fit a UBEC directly into the B/VCC and connect the UBEC to the existing battery, (a little soldering may be required at the battery lead connection on one of the BECs,

OR

You can make up a "Reverse" "Y" Harness out of either 2 extension leads or an extension lead and the lead from a dead/damaged servo.

By reverse I mean a single male plug, (the one that a servo will plug into), and two sockets, (same as the standard servo plug).

Now reconnect the red lead on one of the ESCs and plug the ESC into the "Reverse" "Y" harness.

One one of the "Reverse" "Y" harness remaining leads remove the red wire, (this one plugs into the selected throttle channel).

On the remaining "Reverse" "Y" harness socket remove the WHITE wire. This lead plugs into the B/VCC port of the Rx. This should allow the ESC to provide power, (5V) to the 4.0 - 8.4V input whilst isolating the 5V from reverse voltage feeding of the Rx.

Before soldering and modifying try removing a white wire from an ESC and plug it into the B/VCC port whilst at the same time ensuring there is not red wire connection to the output Rx ports from any other ESC. If it works then the "Reverse" "Y" Harness will work for you and that Rx.

Let me know what you find!

have fun
Of the two which would you recommend? Personally I like your UBEC idea, as it seems much less complicated. Do you have one you recommend? Ideally it could be ordered off amazon
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#36
Of the two which would you recommend? Personally I like your UBEC idea, as it seems much less complicated. Do you have one you recommend? Ideally it could be ordered off amazon
Seriously any UBEC capable of handling the battery voltage and gives 3A output would suffice. (Just make sure it is a Switching regulator to keep it all efficient and cool!

If you can afford or source a UBEC it is obviously the better or simpler choice. Before you buy any UBEC though try powering the Rx using one of the ESCs in the B/VCC port, (with the white wire removed, and no motor connected) to ensure that a BEC is capable of sustaining its proper operation!

Have fun