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Motor won't start- Craftex CT129N

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Suburbanv8

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#1
Hi all, I recently received a mini milling machine from one of my good friends and ever since I got it, the motor has not started up (part of the reason why I got it free). It's a Craftex CT129N, which I had never heard of until now. I assume it's some sort of off brand Chinese thing. I have always wanted to get into machining, and I do have some experience from school, so I thought now would be the perfect opertunity to get started. Anyways, when I learned that the motor was not turning on, I started to diagnose some problems. First off, when I opened the dro, the negative wire coming from the wall was disconnected somehow, so at first I thought that was the problem, so I fixed it by soldering it back together and heat shrinking it (pictured below).
I also discovered that the data cable for the rpm digital screen, was disconnected. After I have fixed those issues, it didn't seem to affect the motor, but it did at least enable the digital Rpm readout to work. After that I started to take a look at the motor and connections to the motor. I turns out according to my owners manual there is an entire fuse missing from the dro. Even more interesting is that I can't find anywhere where the fuse would have gone!? A picture is provided to further your understanding. I also just discovered that there seems to be a ground wire that is missing from the motor. This all seems kind of strange to me, it seems like someone messed with it. If you know anything about the fuse and where it's so post to go and how it gets wired in, or if you know anything about how to wire in the ground cable for the motor please let me know. Thanks you for you time and thought, Anton Schuster

IMG_20170825_110137.jpg IMG_20170825_110111.jpg
IMG_20170825_110151.jpg IMG_20170825_110218_1.jpg
 

Ulma Doctor

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#2
i don't have that model machine, but most Chinese machines use a brushed or brushless DC motor with a board that converts ac to dc and controls the motor.
there should be a positive and a negative connection on the motor, with possibly a secondary earth ground.
the control board will have power and ground wires integral to their design, providing both DC positive and negative polarities for motor control.
you could brew up a 24v transformer/ bridge rectifier circuit and test the motor function

or you could do the same thing by hooking the motor up to a car battery (without a bridge rectifier) and test function.
the motor may turn slower than normal with 12v, but if the motor is working, it should turn
 
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Suburbanv8

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#3
i don't have that model lathe, but most Chinese lathes use a brushed or brushless DC motor with a board that converts ac to dc and controls the motor.
there should be a positive and a negative connection on the motor, with possibly a secondary earth ground.
the control board will have power and ground wires integral to their design, providing both DC positive and negative polarities for motor control.
you could brew up a 24v transformer/ bridge rectifier circuit and test the motor function

or you could do the same thing by hooking the motor up to a car battery (without a bridge rectifier) and test function.
the motor may turn slower than normal with 12v, but if the motor is working, it should turn
I'll be sure to try that, I'll get back to you invest of tried that, thanks so much for the input ,it's really appreciated! Anton
 

Linghunt

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#4

markba633csi

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#6
See if you can determine if the motor or the controller has failed. If the latter, and you can get hold of a schematic diagram (or even if you can't) let us know
and we'll go from there
Mark S.
 

brino

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#7
I _think_ this is the same manual as above:
http://busybeetools.com/content/product_manuals/CT129N.pdf

It also says the motor is:
upload_2017-8-25_20-42-2.png
This manual also gives this wiring diagram:
upload_2017-8-25_20-42-51.png
I only see the one fuse in the "hot" line in, where it should be.

It says:
upload_2017-8-25_20-44-23.png
upload_2017-8-25_20-44-40.png
An exploded view of the electrical box is shown on page 18.

I originally thought maybe a safety switch was causing your motor not to run (like a lock-out switch on am open panel or belt cover, etc.), but I did NOT see that mentioned in the manual.

Good Luck!
Please let us know how you progress.

-brino
 

kd4gij

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#8
You can test the motor with a 12 volt car battery or any 12 to 20 volt cordless tool battery.
The fuse needs a panel mount fuse holder with a 10 amp fuse. the black wire in the power cord that is taped together is the hot wire and the fuse goes inline with it

upload_2017-8-25_21-25-7.png
 

markba633csi

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#9
Hi Anton: That black wire you repaired is indeed where the fuse was. You may have to enlarge the hole in the rear plate when you replace the fuseholder.
You can replace the motor ground with a new wire; pick a convenient place on the mill to attach it. The mounting hole on the motor is probably a metric size screw.
Mark S.
ps If the controller is dead you may have some more troubleshooting in store- try to post a picture of the circuit board if that is the case
 

Suburbanv8

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#10
So after a trying a few of your tricks, I have determined that the motor is burnt out. I put it up to my car battery and nothing happened. Also in the mean time, I installed that panel mounted fuse holder, which is good considering I don't want the machine to burn down to the ground. Thanks everyone for all the advice and help it's really appreciated, I'll update you all once I receive the new motor. Thanks , Anton Schuster IMG_20170826_150858.jpg IMG_20170826_150903.jpg
 

silence dogood

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#12
Are you sure that is a 12volt motor? Many of these motors run on 100v dc. The speed is determined by PWM or pulse width modulation. Or to put it simply, the motor speed is controlled by dc pulses. The wider the "on" pulse in relation to the "off" pulse, the faster the motor runs. There are two things that you need to look at. One are the transistors mounted on the heat sinks and the motor itself. Look for any burnt areas. Do the smell test, you may be able to locate it by the burnt smell. Also look at the electrolytic capacitors. They should look like a cylinder with a flat top. If the top is rounded, then there is a problem. Hope this helps.
 

markba633csi

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#13
I'm suspicious of your diagnosis as well- was there any sparking at the wires when you tried it with the battery?
Motors seldom fail completely, the controller is the most likely culprit however a failing motor could (in rare circumstances) damage the controller too..
Mark
 

Suburbanv8

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#14
Are you sure that is a 12volt motor? Many of these motors run on 100v dc. The speed is determined by PWM or pulse width modulation. Or to put it simply, the motor speed is controlled by dc pulses. The wider the "on" pulse in relation to the "off" pulse, the faster the motor runs. There are two things that you need to look at. One are the transistors mounted on the heat sinks and the motor itself. Look for any burnt areas. Do the smell test, you may be able to locate it by the burnt smell. Also look at the electrolytic capacitors. They should look like a cylinder with a flat top. If the top is rounded, then there is a problem. Hope this helps.
I'll be sure to inspect the motor before I get a new one. Thanks for the tips

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Suburbanv8

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#15
I'm suspicious of your diagnosis as well- was there any sparking at the wires when you tried it with the battery?
Motors seldom fail completely, the controller is the most likely culprit however a failing motor could (in rare circumstances) damage the controller too..
Mark
There were no Sparks at the wires when I connected the motor to the battery. If the controller did fail, where would I be able to get a new one, or could I service the old one? Thanks for your time, Anton

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kd4gij

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#16
A 110 volt dc motor will run at a slow speed from a 12 volt supply like 20 or so rpm.
OP post a clear pic of the front and back of the controller board. Some one here may recognize it. And you did use the 2 leads coming out the motor and not the chase ground, right.
 

markba633csi

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#17
Ok Anton it does sound like a bad motor. Probably one of the brush wires came off inside, or (rarely) very worn brushes. Us DIY types always try to do the
cheapest possible fixes before throwing in the towel and shelling out for new stuff.
Speed controls can be fixed but it can get involved, more difficult without a schematic diagram but sometimes possible. If the motor went open circuit while running the controller may very well be damaged. You might could try substituting an incandescent bulb for the motor and see if you can vary the brightness- may work or not depending on the controller design
Mark S.
 
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tq60

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#18
Get a voltmeter and measure the voltage on the wires to the motor before doing anything else so you can determine if controller is outputting any voltage.

Next motor with 2 wires and compact size likely a permanent magnet type with brushes.

It could have a bad brush or wire and these can be easy repair and brushes are hard to find but tool repair places sometimes have them ot automotive re builders where you may find one close that can be sanded to fit.

When you take it apart the brushes may spring out so place in a plastic bag and push out towards end that power wire is on and hopefully will come out .

They often have place for wire to insert to hold them for assembly.

We are guessing....as we seen this before....brush holder is plastic and user may have pushed it too hard and caused excessive current which caused brush to get hot and melt the plastic allowing it to grab the brush then a little wear and no contact.

Can be repaired with epoxy to add strength then carefull pull brush then file inside holder for clearance.

Good luck

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whitmore

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#19
So after a trying a few of your tricks, I have determined that the motor is burnt out. I put it up to my car battery and nothing happened.
Most DC motors use brushes; a bit of dirt that keeps the brushes from moving can stop the motor,
and just takes a swipe with a pipe cleaner to fix. Some have permanent magnets, and can
attract shavings, too. There may be a thermal overload (with either a pushbutton reset
switch, or a replaceable fuse). I'd disassemble the motor and inspect before ordering a new one.
 
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