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Old Nov 15, 2012, 11:37 PM
Registered User
United States, TX, Houston
Joined Oct 2012
50 Posts
Help!
Need Microtex 20/5/18 repaired!

Anyone know where to get a 20/5/18 repaired or if they are even worth repairing?

Main motor leads came off before I ever mounted it in a plane. Might need to be rewound with longer leads to solder to the 3 main power wires.

Or maybe some one can guide me in rewinding it myself to learn how.
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Old Nov 16, 2012, 07:16 AM
Jack
USA, ME, Ellsworth
Joined May 2008
16,338 Posts
Were the leads soldered to the G-10 terminating ring as seen here?

http://www.lightflightrc.com/HTML/pr...Tex20_5_18.htm

I don't know that motor but it looks like the intention is that the leads to the ESC be soldered to the three pads on the back of that G10 terminator. That is about the only way to keep the fine winding wire short, close to the motor, and well immobilized from vibration.

As far as rewinding it, it is a 9 pole stator right? And it will probably have a ABC wind on it.

Here is the instruction manual for a Komodo 9 arm stator kit motor, that shows the basics of what you want to do. Pay close attention to how you motor is wound and terminated and count the turns on an arm or two as you strip it. That info will be needed to give you starting point for the rewind, turn count, and termination on the rewind.

http://www.micronradiocontrol.co.uk/.../KH-278-v2.pdf

I don't know of a place that will repair or rewind it for you.

Jack
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Old Nov 16, 2012, 09:33 AM
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G10 terminating ring???

G10 terminating ring??? WHAT G10 terminating ring!!!???

So he sold me an incomplete motor!!!

That's why the wires keep breaking! No terminating ring!
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Old Nov 16, 2012, 09:54 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Like I said, I don't know that motor and was just guessing at answers. I found that page in a google search. Not sure what your should have gotten with it.

In your photo there is some kind of dark plastic or metal piece that the one wire passes through, is that a mount or something?

Here is another type of winding terminator, they are not very commonly used any more but really help when you have fine winding and need a transition point to go to stranded wire from:

http://www.strongrcmotors.com/Winding%20Terminators.htm

That one is for an 8mm tube and maybe larger motors, like 22mm or so O.D.

You can buy G-10 in various thicknesses and even make your own terminators. Just loop the stripped and tinned winding wire through a hole near the edge, then stick the tinned end of the stranded wire in next to it, and join them with solder.

The image is a AXI 1806 motor, you can see another type of terminator there and one is mounted on the tube behind motor to transition to stranded leads for the ESC.

These little motors can make you crazy as far as working on them...

But it is good clean fun!

Jack
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Old Nov 16, 2012, 10:14 AM
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The black part is a plastic cover on the back. I am in the process of taking it part now to give it a shot. Will figure out a terminator solution from what you showed me. That helps a lot.

Might not be worth much but darn I can say I fixed it!
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Old Nov 16, 2012, 10:34 AM
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There are 4 wires on each winding. its a 9 pole motor so not sure why 4 wires per winding. Each power lead had 4 wires attached to it and these went to the windings. Looks like all windings are tied together on the other end.

Motor is a 20/5/18

Is that 20 gauge 18 turns or 20 turns 18 gauge? And what does the 5 mean???
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Old Nov 16, 2012, 11:30 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by bayou_city_boy View Post
There are 4 wires on each winding. its a 9 pole motor so not sure why 4 wires per winding. Each power lead had 4 wires attached to it and these went to the windings. Looks like all windings are tied together on the other end.

Motor is a 20/5/18

Is that 20 gauge 18 turns or 20 turns 18 gauge? And what does the 5 mean???
It looks like they used four finer strands in parallel then to take the place of one larger strand. The strands are joined at each end so the surface area is the sum of the four smaller strands. It makes for a more flexible winding wire that may be easier to wind than single larger strand. And also lets you add or subtract strands to get the best fill of copper if there is more room or not enough room for the turns needed.

The turn count and termination determine the Kv, the wire size determines the current capacity. More surface area = more current.

Look at it carefully. In a ABC wind the wire will start on one arm, then skip two arms and go to a third arm, then skip two more and go to a third arm and that will be one of the three phases. So it would be like:

phase 1 - arms 1, 4, and 7

phase 2 - arms 2, 5, and 8

phase 3 - arms 3, 6, and 9

So when it is wound you have six ends. If three of the ends are joined with three other ends it is Delta terminated.

If three ends go to the ESC and the other three are soldered together, insulated, and just laying there somewhere they it is Star or Wye terminated.

It is important to know the turn count and termination to get the Kv the same.

"..Motor is a 20/5/18..."

That probably means a 20mm O.D. and 5mm height on the stator or the rotating magnet housing. The 18 might be the turn count or it might even mean something like 1800 Kv. There are no standards or rules for motor names.

If you measure the strands and find them about 0.25mm (0.010") that is about 31 AWG wire. And that is a typical size. In theory, if it was wound with four strands of 0.25mm wire you could wind it with one strand of 25 AWG wire and get the same surface area. If you can get the same number of turns on with 24 AWG wire it will have morer surface area and handle more current. You can study the numbers on wire sizes, surface areas, and all of that here:

http://en.wikipedia.org/wiki/American_wire_gauge

Strong Motors is a good place to buy wire. The wire from Radio Shack is cheap junk wire. But is OK for practicing winding with. Practice with it and then throw it away, don't put current on it...

Jack
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Old Nov 16, 2012, 09:13 PM
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Couldn't get wires off. Looks like they used some kind of sealant to secure them.

Went and bought a new motor.
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