Thread: Milling control box component ID

Today my Jafo milling machine passed on.... I was milling away, then stopped the machine.. Went to restart and totally dead... not a thing going on it...

Checked power supply, stop buttons, fuses, all good..... It has a heap of relays and also a transformer some components I cannot identify....

The first one as shown in the picture seems to get fed 240V from the transformer into it.. I assume all the relay's run off 240V control voltage... This component has a thing that you can spin and it will slowly wind back over two seconds or so...

The other is some sort of coil and things.... No idea what that does either.... it seems overly complicated to my way of looking at it...

Anyone have any ideas? I have no wiring diagram...

The middle picture looks like it contains Diodes for some sort of DC Control.

Well it works again now... Just started up like normal....

I have discovered what the thing is in the first picture.... it is a timer... This mill has a brake attached to the main drive motor... When changing speeds there is a button you press that releases the brake but the motor does not spin, so you can easily change gears... I noticed today after it started working that if you press the brake unlock button the timer starts spinning then when it reaches it's limit it cuts out the relay and the brake locks on again..

Hi RC,

I agree there seems to be a lot going on in there.

When you say "not a thing going on it" I assume you mean powerfeed and coolant pump aren't working either?

What else does the mill have?
Does the rotary switch (top right) control fwd/rev?
Is the tranformer under that perspex(bottom right)?

Stuart

p.s. nvm, fingers crossed it keeps going

Hi .RC,

Good news that it's going again... keep your fingers crossed...
If it happens again, and the whole machine seems dead, then, assuming the mains power is good, I'd start with tracing the e-stop circuit, what you should have is a latching contactor that unlatches when the e-stop loop is broken.. there will be multiple places around the circuit, usually a big-red button or two, and maybe other places around the machine... maybe some travel limits?

Regards
Ray

PS... Now would be a good time to try and find a circuit diagram, ready for the next time it stops...

Hi Ray, I assumed it was a fault somewhere early in the power supply since everything was dead... I checked both e-stop buttons and they were OK, but I did not check the wiring..

A wiring diagram would be handy, but this machine seems to be an orphan.. Plenty of Jafo milling machines around, but not of this model..

Hi .RC,

That e-stop latching contactor will be the first thing in the power cct. Somewhere there will be a start/power button that pulls it in, thus providing the power to the rest of the machine. If it's an open cct in the e-stop loop, pressing the start/power switch won't do anything, and everything will be dead.

I'll have a closer look at those pictures (later) and see if I can trace a few wires...

Regards
Ray

Hi Ray,
My guess is it has two e/stop contactors. The two big brown ones on the left.
Motor (top middle black)
Coolant(bottom middle black)
Power feed (bottom right black)
The two brown things on the right I'm not so sure about, If the mill has an on'off switch rather than a press button, some logic to make sure the machine doesnt restart when the e/stop is removed.

Unless the fwd/rev of the spinlde is controled by push buttons rather than the rotary switch. In which case I take most of that back lol

Surely the controls wouldnt be 240V?

Now I'll leave it to the expert

Stuart

I have done some testing and there is no power relay so to speak...

The relays click in as per this diagram...

There are three relays that have what I assume are overloads connected to them.. These are a constant that click in as each motor is switched on...

Motors like the coolant motor cannot be started unless the main drive motor is running... Same with the table feed motor, it cannot be locked in unless main drive motor is running, but you can run it as a jog switch with nothing else running..