micro mill electricals problems, help please!!

[pmdevlin]

received thanks John.

I've been doing some internet trawling, and it appears there is a sieg mill with an ac motor, who know's what I have! The instructions that came say super X1, yet all sieg are red, mine is green, and has a belt drive conversion.

I will photo the damned motor sticker tomorrow, it might help with all  my ramblings!, must be frustrating to you guys when an idiot arrives, like me!

Paul

[BaronJ]

I have challenged the guy but he keeps coming back with the fact it has a big spec sticker on the motor, and it says "AC". I too also think he has fried the motor, inadvertently, but as he is the "expert" should he have known this? .

I agree with you.  But as an "expert" he does have a duty of care.  Did he charge you any money ?  Did he give you a work sheet ?

I think that you will find that the label on the motor refers to the combination of both the controller and the motor.  Unfortunately I have seen and used motors that use "AC" but look very similar to "DC" ones.  Without knowing what to look for it would be easy to mistake one for the other.

I was very specific with my description as to what had happened, then surely he would have seen the output was DC, not AC?, and would have been able to assess if the board or pot was faulty.

Unfortunately he would not touch the board as he wanted a circuit diagram, so I have gone backwards really, to the tune of £88 motor, surely there are cheaper alternatives out there?

Paul

I'm afraid that his refusal to have anything to do with the control board and wanting a circuit diagram, would have rung alarm bells with me, and I would have quickly walked away.

[pmdevlin]

I'm afraid that his refusal to have anything to do with the control board and wanting a circuit diagram, would have rung alarm bells with me, and I would have quickly walked away

Unfortunately I only found this out today on the telephone. I have a plan, tomorrow I will get him to confirm the output, from the control board he will then have to confirm if output is dc or ac, lets see1

[steampunkpete]

Paul,

Just to satisfy my curiosity, could you post a picture of the label on the motor please?

Peter

[pmdevlin]

motor has been collected, I will collect controller later, I have insisted he checks output, to satisfy me its either ac or dc, and the pot is doing something!

[lordedmond]

Ok

First pic is the tag for the mill as a unit

The last pic clearly states its a DC motor so your expert burnt it out  QED

Stuart

[matnewsholme]

Yep the big sticker is ratings for the entire mill as a unit. Main power input to mill is 220-240v AC. Motor doesn't have a mt2 spindle taper. Pretty obvious smaller sticker is the actual motor spec and it's clearly DC. If you look above the cable on the first picture you can see the end of the brush cap ( round black thing with a screw driver slot). AC motors don't have brushes. He's fried your motor and should pay for replacement IMO.

[John Rudd]

Yep the big sticker is ratings for the entire mill as a unit. If you look above the cable on the first picture you can see the end of the brush cap ( round black thing with a screw driver slot). AC motors don't have brushes. He's fried your motor and should pay for replacement IMO.

Ahhh. But universal motors have brushes too....have a look at your Bosch electric drill/planer/ sander.....
A typical DC motor is either perm magnet or separate field coils energised with a DC supply....not connected in any way to the brushes....(a universal motor has the field coils in series with the brushes typically...)

[pmdevlin]

just found the motor at arc euro, its a dc motor, so I have to agree, he has fried it, by reading, like me, the main sticker, now its been pointed out, its clearly for the mill, not motor, so original fault lies with board, or pot, and I bet its the flippin £5 pot!

So its back to him later, and arguing the point, I hate this confrontation, I'm an honest easy going guy and expect same back, hopefully he will realise his error when he tests output of controller and does the right thing by me, hmmm, not holding my breath!

I have identified the board from serial numbers on the pics shown on arc euro site, looks like NOBODY else sells these motors or controllers, Hopefully John can save the board!

[matnewsholme]

Forgot about universal motors as it's not something I tend to come across tbh. But his motor is clearly labelled as DC, so still think his expert is at fault.

[lordedmond]

Paul
 Be careful with your expert he no doubt come back and say the controller is outputting AC , but it's pulse width DC

No doubt john can explain more eloquently than I but it's output is on for a time and then off for another time period , eg on for 50% off for 50% gives you approx half speed , that's what the pot does it varies the on off ratio hence the speed .

Note the volts remain the same but it's only switched on for a short time for low speed and on for longer to give higher speed .

To test you need a load and an oscilloscope

Stuart

[steampunkpete]

I suggest that before the motor is written off a burnt out / fried, it is tested to check that is indeed the case.

Putting AC into a DC motor will only damage it if the stall-current - time integral is sufficient to raise the temperature inside the motor to the point where there is some critical damage (such as loss of insulation or commutator distortion).

What the PM DC motor does if it is fed AC depends on the nature of the input, the electrical characteristics of the armature, the mechanical time constant of the armature, the thermal properties of the system and, to a lesser extent, frictional forces. A typical response is that the armature will vibrate at 50Hz - it will hum happily to itself (until it burns out, if it is going to).


If the AC has only been applied BRIEFLY then there is a good chance that the motor is OK (remember that if he has tested it a 110V AC then he has put less power into it than its 240V DC rating). You could test it by carefully connecting it to a 12V car battery and a fuse which should be enough to get it turning. (NOT via the cigarette lighter in your car, just in case!). If it turns its probably still good. If it doesn't turn its definitely 

[John Rudd]

Yup I agree with Pete,if the applied ac source was on for a brief period then theres a fair chance it might have survived the ordeal...
A little more than 12v dc will be needed tho' to get it to spin up.....24v more like...
This where a variac comes in handy...( with a bridge rectifier of course...) for testing....
Growler testing will reveal any probs with the windings...

[lordedmond]

Good grief there John not heard the term growler for a long time .

We did not call them by that name in the winding dept but the name is very not PC now

Coil and a hacksaw blade it what we used a long with the normal drop test and IR of course

But we only did DC motors to about 100hp but the converters 6 phase in DC out were about 500hp with open knife switch starters

I hope I have not confused Paul with my ramblings

Stuart

[pmdevlin]

ha ha, I was confused the minute the fuse popped! Stuarts comments regarding pulse width are going to make things very difficult for me regarding any recompense for the motor, if indeed its burnt out, I reckon he will still insist its ac output so I am snookered really.; I do think he is a genuine guy and is probably making a  huge mistake without knowing, anyway, I'm off to get the controller now, if he says he still hasn't touched it its coming home anyway, for a destination close to the East coast.!

[lordedmond]

Paul you don't need to let on you know how it works just hope he don't read this forum.

John will fix you up


The controllers do not output AC just lumpy DC 😳

Good luck and be safe remember you cannot see it nor can you smell it but you can feel it

Has as been said unless the magic smoke was let out of the motor you should be ok

Stuart

[BaronJ]

motor has been collected, I will collect controller later, I have insisted he checks output, to satisfy me its either ac or dc, and the pot is doing something!

That first picture refers to the machine the motor is fitted to !  The third one is the motor specifications.

Your expert is both blind and stupid.

[pmdevlin]

went back, as arranged, he had shut up shop and gone! Now I know its New Years Eve and all that, but he knew I was coming back, he could have just rung me, so he got the voicemail from Satan himself!

I've told him (and will ring him after holiday) he has cooked the motor, and I want the controller back, assuming he has done nothing as I could see it through the window in exactly the same place I left it

I've put 12v on the motor, don't have a 24v source, it was def trying to turn, Stripped it again, cant see any damage or evidence of burning, no smell, nothing out of the ordinary, maye I have been lucky!

Happy New Year, nad a massive thanks to all contributors to this thread

Paul

[John Rudd]

I've put 12v on the motor, don't have a 24v source, it was def trying to turn, Stripped it again, cant see any damage or evidence of burning, no smell, nothing out of the ordinary, maye I have been lucky!

Paul

Is your 12v supply portable? You could try hooking it up to your car battery to give you 24v...(just be careful not to short anything out.... )

Otherwise you could use your battery in conjunction with a 12v bulb wired in series to prove the continuity of the windings by going across each pair of  segments on the comm....
Shout up if you need a bit more of an explanation....
Off to the electronics section now to read replies on my pc issue...

[pmdevlin]

picking the controller up in  a few days, After lengthy phone conversation, he has agreed if I can prove its a dc motor (well its got a sticker on the can!) he will take responsibility.
To be fair, I will do Johns test on the motor, so, just need an idiots guide as to how to do this! I assume if bulb goes out on any segment, then the motor is actually duff?

Paul

[lordedmond]

Paul

To keep all your fingers  get a 3 volt battery and a 3 volt lamp

Connect up battery lamp motor and back to the battery all in a long chain turn the motor by hand very slowly ( it will be better one way) and watch the lamp it may flicker but as you have thought out any dead segegments are bad news

The reason for three volts is there is no possiblity of the motor turning , thus safe

Now this is not the way I would do it I would do a volt drop test on the armature but that requires more equipment , or a growler test , that uses a coil with lamination fed with AC and held on the armature laminations a old hack saw blade held on the other side will rattle if a short is present
As a last comment if it looks ok and smell ok it should be OK if he did not leave it on AC for long , it would have made a loud hum and not rotated , henc his misinformed diagnosis due to fault testing methods

Hope you get it sorted with a little impact to the wallet

Note I refer to lamps it's because they go in lamp holders and bulbs go in the garden , remember the clout round the ear hole in 1962 when I started work at the tender age of 15

Stuart

[pmdevlin]

collected the control panel today, and its on the way to Hull!

Having proved its a dc motor (sticker on it!!) expert has kept it to test on high dc voltage, if faulty he has agreed to replace. He confirmed he used the large micro mill spec sticker thinking it was referring to the motor.

Hopefully all will work out ok!

[John Rudd]

Yup,I'll let you know when it gets here and what the problem is....

[steampunkpete]

Keep us all informed John, we are all on the edge of our seats.

If its an MXT-2325 board like mine, I'll have spare diodes and thyristors.

Pete

[pmdevlin]

motor is back with me now. The guy wanted it tested on a higher dc voltage if he was to replace as promised. A fair request I suppose, however, no test can replicate the voltage and load this motor is designed to take. It was tested on 60v dc, with variable supply, he borrowed something to do it, I watched! It ran from a virtual stall speed, up to what the 60v could deliver in terms of speed. Even at low speeds, it was impossible to hold the shaft by hand, so the torque was certainly there. No heat, no smoke, it ran for some time, so I had no option but to agree he got off the hook

If John has some luck with the controller, it will be a nervous time turning it all on again, I hope the motor is actually ok, he says it ran only for seconds on ac so I think we should be ok. I have stripped it again, no signs of damage, heat or any smell of electrical death!