PDA

View Full Version : Lathe Control Repair Notts/Derbys



Chas
01-01-2011, 10:37 AM
Does anyone know of an individual or company offerring on-site electrical repairs to machinery in the Notts/Derby area?

I have a Seig CQ6230B lathe that went bang a couple of months ago & my very limited knowledge of lecktricity is not helping to get it up & running.

The 240-24v transformer definately burnt a wire but replacing this hasn't solved the problem, I think something else, possibly a contactor is faulty which caused the transformer to burn out.

It's a single phase 240v machine with 24v controls running a 1.5kw single phase double capacitation induction motor.

I don't know if it'll take a man who knows 2mins or 2hrs to diagnose but it'll take me 2yrs+ to learn lektronix from scratch. I've put the lathe up on castors so it can be easily wheeled around for access.

You are my only hope, I have work waiting for it but it's just scrap metal at the moment & far too heavey for me to chuck it out of the window :-)

3520

Swarfing
01-01-2011, 11:03 AM
Chas

If the whole unit will not power up or just trips straight away, you have no bare wires then suspect the transformer itself. If it is only part of the lathe that does not work then it would be the contactor for that circuit (normally just the energising coil). There is not a lot that can really go wrong, i'm wiring a new lathe up from scratch at the moment myself. What does each contactor feed? tell us more about the controls? is the contactors controlling motor, pump, light etc?

Chas
01-01-2011, 11:53 AM
Chas

If the whole unit will not power up or just trips straight away, you have no bare wires then suspect the transformer itself. If it is only part of the lathe that does not work then it would be the contactor for that circuit (normally just the energising coil). There is not a lot that can really go wrong, i'm wiring a new lathe up from scratch at the moment myself. What does each contactor feed? tell us more about the controls? is the contactors controlling motor, pump, light etc?

In my picture from left to right.

Contactor 1 = motor forward
Contactor 2 = Motor reverse

Contactor 3 = coolant pump
Contactor 4= unknown

I've just found out that pushing in the contactors gets the motor running regardless of the lathes forward/reverse switch.

When I switch the lathe on, there is no 'clunk' like there used to be.

Is contactor 1 at fault?

Chas
01-01-2011, 12:08 PM
First electric shock, luckily only 24v.

A small crowd is gathering . . . . I might make some smoke before the day is done.

Swarfing
01-01-2011, 12:53 PM
Ok if you have 24v showing the transformer may be ok? not sure why there is a need for a separate contactor between forward and reverse? will it run in reverse ok? if yes the the first contactor is duff (assuming the second contactor does not get fed from the first). Try swapping the first contactor with the second (make notes of all the connections as i see somebody has taken the trouble to number them). To replace all these conmponents would be cheaper to do than call somebody out and pay for the parts on top as well so consider a trip down to the electrical factors. Is the machine 3 or single phase?

Swarfing
01-01-2011, 12:56 PM
Consider 230v contactors and do away with the 24v transformer? you may even be able to get new coils on there own for the contactors if they are removable.

m_c
01-01-2011, 09:11 PM
230V contactors are not a good idea!
24V is far safer for controls.
And the seperate contactors for forward/reverse are to rewire the start capacitor so the motor starts up the opposite way, that way you don't have 230V at any of the control panels.


Have you got access to a multimeter?
And was there any fuse on the 24v side of the transformer?

Swarfing
01-01-2011, 11:00 PM
With the right switch there is no need for a separate contactor with appropriate circuit protection, it should not make any difference whether it is 24v or 230v. The circuit i used for my mill works with a single contactor no trouble at all on 230v coils.

If they have gone to the trouble of adding lots of contactors whether there is one for a brake on the motor? does one exist?

m_c
01-01-2011, 11:31 PM
And by the time you find/buy new switches and contactors, and change the wiring, it'll be the far more expensive option.


You say there was a burnt wire. Where did it go to/from?

Chas
02-01-2011, 11:23 AM
The burnt wire was in the transformer itself, it's all the visible evidence I can find. I've got a replacement transformer of the same values but it's too big to fit inside the box, I'm having to temp wire it up outside untill I can find the right sized one.

The only fuses (other than the 13amp plug) are the MCB's, none blew or tripped.

I've got a multi-meter but don't really know how to use it, I'm OK at ID'ing what voltage from what wire & continuity etc but please don't ask me to start measuring OHMs or amps etc.

Swarfing
02-01-2011, 11:51 AM
Chas this would suggest then that the transformer is the main issue and would get another before doing anymore. As long as it is 24v DC then you could use a 24v din rail bell transformer. The type that powers a door bell. They are normally about an Amp or more. What is the coil rating of the contactor?

m_c
02-01-2011, 02:12 PM
You shouldn't really need to worry about amps or ohms for most wiring.

What you'll need to do is figure out where power is going, and where it's not.
By the sounds of it, something has caused the old transformer to burnout, so I'd be inclined to install a fuse in secondary (tha't the low voltage) side wiring. A quick and simple fuse holder for testing purposes, are two 1/4" female spade connectors (ideally fully insulated, but uninsulated with a couple wraps of insulating tape will do) and a normal automotive blade fuse.
What caused the transformer to burn out may be one of many things. A faulty switch, contactor, or a wire chaffed somewhere.

What you need to do, is wire the new transformer, and then start seeing where you are getting power to, and where you're not.
It'll obvisouly start at the transformer, go via the switch(es), through any safety interlocks, before arriving at the contactor.

To help, get a sheet of paper, and make a rough wiring diagram of the bits you know as you go along. It doesn't need to be a work of art, or use the proper symbols, just something that you can understand, and make reference to as you check things. Start with the low voltage terminals of the transformer, and add lines/notes/components as you trace where the wires go.

m100
04-01-2011, 02:10 AM
Why not just contact SIEG and get a wiring diagram? http://www.siegind.com/message.php Or failing that contact whoever imported the machine, assuming it wasn't a fly by night ebay seller.