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Tony Nijhuis 50" Vulcan EDF version

Nightmare electrics!!

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Martin McIntosh25/09/2020 09:57:51
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Good advice there but remember what I said above about the HK MCR series retracts no longer working with certain Rx`s. They should work OK on a servo tester though, so this may mislead.

Nik Harrison27/09/2020 16:40:14
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96 forum posts
163 photos

TonyS,

I was looking over previous posts on this problem. Namely your post of 31/08/20 in which you showed the circuit you were using.

The problem is the 0V connection. You do not have any 0V connection between the two LiPo batteries therefore each pair of ECSs are using a different reference. This means the second battery supplied ESCs do not understand the signals given to them, so do not respond.

Install an 0v connection between the LiPo leads and I'm sure things will improve. This does not have to be a high current cable as high current should not be going down it.

Martin,

Having followed your Concorde build I'm still waiting to see air underneath it! Don't disappoint me. Lol.

Cheers,

Nik

Martin McIntosh27/09/2020 17:57:09
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So am I Nik. I am booked in tomorrow and Tue. but it depends on the wind and even if the grass has been cut the cuttings would stop me again.

TonyS27/09/2020 19:35:39
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327 photos

Hi Nik,

This all sounds very positive. It would be really helpful if I had the slightest clue what an 0v connection was or how to make it. Answers on a postcard (or via this thread) would be very welcome indeed...

Thanks\

T

Nik Harrison27/09/2020 19:49:46
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163 photos

TonyS,

I'll get a drawing together tomorrow and post it. How is the problem with the undercarriage going?

Cheers,

Nik

TonyS27/09/2020 20:06:22
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1211 forum posts
327 photos

Thanks again Nik,

this could be the only route to keeping the project rolling.

sadly my father in law was taken ill (in the QE in Birmingham with pneumonia 😬so we’ve been too preoccupied to allow for model fixing/building. Hoping he’s on the right path now so maybe I’ll get an hour tomorrow.

T

Edited By TonyS on 27/09/2020 20:06:49

PeterF28/09/2020 09:42:19
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578 forum posts
740 photos
Posted by Nik Harrison on 27/09/2020 16:40:14:

TonyS,

I was looking over previous posts on this problem. Namely your post of 31/08/20 in which you showed the circuit you were using.

The problem is the 0V connection. You do not have any 0V connection between the two LiPo batteries therefore each pair of ECSs are using a different reference. This means the second battery supplied ESCs do not understand the signals given to them, so do not respond.

Install an 0v connection between the LiPo leads and I'm sure things will improve. This does not have to be a high current cable as high current should not be going down it.

Martin,

Having followed your Concorde build I'm still waiting to see air underneath it! Don't disappoint me. Lol.

Cheers,

Nik

Nik,

As the ESCs are BEC type I would expect them to have common negatives from battery side to signal cable side so they would have a common negative reference so on a simplistic basis they should be OK as the 4 in 1 cable ties them all together. Am I missing something, is there some issue of small current flows through the one ESC to power the model causing voltage differences on the negative cable.

I have a twin with wiring like Tony's and separate batteries, it works OK, but in thinking about this, I have battery pack telemetry on both flight batteries and this provides a common negative link between the two batteries. Perhaps I have just answered my own question.

It is certainly worth a try.

Peter.

Nik Harrison28/09/2020 12:45:46
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96 forum posts
163 photos

TonyS,

Sorry to hear about your father-in-law and hope it all works out OK.

I have done a few experiments with my own set ups to check I'm making sense. PeterF is correct that the signal 0v is connected to the LiPo 0v internally on each ESC. I double checked on some of my own ESCs. My fault sorry. blush

fourfansetup.jpg

Back to trying to work out what is wrong.

To double check that the 0v connections are as they should be could you check a few points with a Digital Multi Meter (DMM). If you haven't got one they are not expensive and extremely useful.

1. Check continuity between A and B, then between A and C.

2. Check the signal connection (white) between A and each ESC.

3. If it is still not working try changing which ESC supplies the power. i.e. from 3 to 4. This should prove whether ESC 1 & 4 work. Maybe with ESC 2 & 3 disconnected. I tried an experiment where I powered up an Rx then powered up the ESC to emulate your original ESC setup which powered 1 & 4 last. It powered up and worked OK.

Hope this at least gives you some ideas where to look.

Cheers,

Nik

Martin McIntosh28/09/2020 18:54:51
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3579 forum posts
1231 photos

Tony S,

0V is the battery negative (-ve, the black or brown wires). My Vulcan and Lancaster each use two batteries and the Rx only requires a supply from one ESC; it is a bad idea to let them all supply it so on my four way `Y` leads three of the red wires are disconnected. Each battery supplies a pair of motors/fans. The drawing above looks to be correct to me. I link my ESCs together with a four way socket as supplied with some quads to synchronise the motors when setting up. HK sells them for pennies.

No chance to try the Concorde today because the grass was a little long and damp.

TonyS28/09/2020 19:24:58
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1211 forum posts
327 photos

Nik, Martin,

Thank you both for the help here.

I think that we're on the right track.

Firstly, on a test with a single motor and set up as normal the main leg retract fails to operate. if I swap it out on the three way lead with a basic servo the servo works so it seems to me that for some bizarre reason the retract has packed up! Considering it did work and hasn't been anywhere but the bench I can't work out why it's suddenly broken. I've checked the wires and they don't seem broken so I'll check with a DMM later. If it's bust I'll need to work out where I can get a replacement.

As for the motors. I've hopefully worked out how to mix channels and put two motors onto the throttle channel on a Y lead and two onto the Aux channel on a Y lead. What happens now is that I can get the two motors that are on the Y lead (with the one delivering power to the Rx) working. The other two simply bleep as if they haven't managed to 'handshake' with the Rx.

The concern I have is that

  1. I may not have set up the throttle/aux mix properly - the instructions in the Spektrum manual don't quite match up with the RX channels available
  2. By putting two ESC's on a different channel they may never be able to initialise properly when the Rx is powered up

I am beginning to think that the build is fine but the electrickery here is getting well beyond the limits of my knowledge.

T

 

 

Edited By TonyS on 28/09/2020 19:25:16

Edited By TonyS on 28/09/2020 19:26:37

PeterF28/09/2020 19:39:12
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578 forum posts
740 photos

Has anyone suggested connecting all 4 ESCs to a servo tester rather than an Rx. That may be another worthwhile test.

When setting up the mix you need to make sure that the end points and trims at zero are correct or the ESC will not arm if it has any signal above 0. I do not use Spektrum so I can not help further.

Peter.

Martin McIntosh28/09/2020 20:13:59
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3579 forum posts
1231 photos

Just looked at the mixes on my Vulcan JR DSX9 and there is nothing on throttle. I cannot see why you would need one since the throttle channel should be connected to all ESCs via a quad lead. The -ve`s will be automatically connected to each other via this lead anyway. In my experience you do not always get a mix output the same as the master channel and sometimes need to increase the travel on the slave. Look at the channel monitor screen if you have one to check this, or just use a couple of identical servos if not.

Retracts. Are they the HK MCR ones? If so you may still be able to get replacement amplifiers for £1 or so but you need to be rather adept with a soldering iron on the motor leads. Thinking that I had some dead ones I purchased a few but then found that due to a manufacturing change they still would not function with certain Rx`s. Spektrum should be fine though. You may well have a couple from a new batch and one from the old.

PeterF28/09/2020 20:27:48
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578 forum posts
740 photos

Martin,

The mix for the throttle channel is in response to my suggestion that the signal current required by four 4 ESCs may be higher than a single Rx output can supply. There are known cases of this. Splitting the ESCs onto 2 Rx outputs with a mix will supply twice the signal current. It was just one of the potential solutions to this odd conundrum.

TonyS28/09/2020 23:03:34
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1211 forum posts
327 photos

Right,\servo tester ordered.

the build goes on!

T

TonyS03/10/2020 19:52:44
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1211 forum posts
327 photos

Martin (et al).,

I’ve tested the retracts with a servo tester and one of the main retracts is dead. Really annoying as it was working fine and I’ve not even finished the build let alone flown the model but hey, ho.

even more irritating is that having dismantled it and unsoldered the servo and motor wires I now find that Hobbyking have no replacement PCB boards in stock. They don’t even have any replacement retracts.

I fear this project is doomed.

So. No u/c and still can’t get all the motors to fire up at the same time.

T

Edited By TonyS on 03/10/2020 19:53:16

Martin McIntosh03/10/2020 20:39:07
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3579 forum posts
1231 photos

Cannot guarantee anything but if you send me the offending unit I may be able to help getting it to function, assuming that it is of the MCR type.

PM me if interested.

Martin McIntosh13/10/2020 17:49:11
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3579 forum posts
1231 photos

Thanks for the gift and glad to see that the u/c units are all now functioning. A pleasure to help if I can. Now the fans-------?

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