Help and Advice sought about new motor for my mill

Hi everyone,
I have a small chinese mill and a couple of days ago I rather pushed it beyond its limits. The motor got extremely hot and then everything shut down causing an rcd in my fusebox to switch. Now whenever I try to switch my mill on it throws the rcd again. So I have either killed the motor, (its a dc 600w type 91ZYT005) the controller board (JYMC 220B I) or the filter board. I can get spares, but the question is which of the components is faulty and what tests can I run to find out? Bearing in mind that I am not an electrical engineer. Today I removed all the electronic boards from their housing and inspected them but nothing looked burnt. I took photos of the connections before I undid all the wiring. But a wiring diagram would be appreciated.

Has anyone had a similar experience and solved it , and so could offer some advice or assistance. Does anyone know which component is most probably affected and how I can check. Or should I just replace all three?

At present it is a manual mill, I was going to add steppers etc in the coming months but obviously now the priority is to fix the mill
so it runs again. However I am wondering how difficult it would be to replace the existing dc motor with a 3 phase ac one connected to an
inverter as an alternative, as this would allow me to control the speed automatically when I do complete the cnc conversion. It seems to me
that I just need to machine a housing to support the motor (how!! now mill not working). Has anyone any experience of doing that and can
offer some assistance?

By the way I do use emc to run another machine that I constructed myself using said mill above and the break occured as I was trying to machine a new component for this, specifically drilling some 20mm diameter holes that I was going to bore out to 25mm to hold some linear rail I had just bought!!

Thanks
Alan

alanb wrote:

Hi everyone,
I have a small chinese mill and a couple of days ago I rather pushed it beyond its limits. The motor got extremely hot and then everything shut down causing an rcd in my fusebox to switch. Now whenever I try to switch my mill on it throws the rcd again. So I have either killed the motor, (its a dc 600w type 91ZYT005) the controller board (JYMC 220B I) or the filter board. I can get spares, but the question is which of the components is faulty and what tests can I run to find out? Bearing in mind that I am not an electrical engineer. Today I removed all the electronic boards from their housing and inspected them but nothing looked burnt. I took photos of the connections before I undid all the wiring. But a wiring diagram would be appreciated.

Disconnect the motor from the drive board. Use an Ohmmeter to check from earth to the motor wires.
If you get a less than infinite reading, the motor is probably shorted to earth. You may be able to fix
it by removing the end cover and fix up the brush holder. In many of these motors, the brushes are
held by plastic assemblies and when the motors get hot, those assemblies melt. It may be possible
to fix them up, or it may be completely beyond hope without fabricating new holder assemblies.
You can do that, or buy a new motor. You can then also check from the copper commutator
to the motor shaft. if you get a non-infinite reading here, the motor is toast.

If the motor checks out OK, then it is the driver board. Turn the safety switch on, and check from
the mains hot pins to the earth pin. If you get a non-infinite reading there, that verifies the
board is popped. There are outfits that rebuild these, I guess it must be a common problem.

Since your RCD tripped, I suspect there will be an easily detected short in either the motor or
drive board.

Jon

Thanks for the advice. I had really mentally almost decided to go for the three phase option. I think I will convert to a timing belt driven setup. So two questions.
1) Would 5mm wide timing belts be robust enough or should I aim for 10mm?
2) Andy, do you use a speed controller or just a phase converter circuit? Just curious.

Alan

Obviously Andy, from your comments I need to look for wider belting.

Alan