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Colchester Student Mk1 Won't Start

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Richard Kirkman 124/03/2020 14:56:43
310 forum posts
761 photos

I still need to connect all the blue yellow and red wires into the contactor? I'm not sure where they need to go, but looking at your diagram made a bit more sense

Or are you saying I need to connect the blue for the holding in switch elsewhere?

I'll get the pictures soon, just finishing some coursework

Richard Kirkman 124/03/2020 15:36:59
310 forum posts
761 photos

Picture on the side of the contactorimg_20200324_152600.jpg

Then my electrician friend put two brown wires into the contactor, I don't really know why, but I'm sure there was a reason for it



Now, As far as i understand, then from the diagram you drew for me, the yellow needs to go into L3, the blue into the holding in thing at the bottom, then the red into the top one?




Phil Whitley24/03/2020 16:01:19
1324 forum posts
147 photos

Hate to be the bearer of bad news, but the contactor appears (from the blue label) to have a 240v coil in it, you need to change this for a 400-415v coilfrown I also need a few good pics of the overload connections, but it will wait till you finish ter Uni stuff!


Emgee24/03/2020 16:35:36
2010 forum posts
253 photos

Could just run a neutral with the power supply and use 240v control.


Richard Kirkman 124/03/2020 16:53:23
310 forum posts
761 photos

This is the contactor that I bought


Yes, it does seem to be 240v, but it says somewhere about 440v being used? Can it be made to work or am I better off ordering a 440v one like this


As if so, I need to order it quickly since who knows how long the royal mail is going to keep going

Sorry about the faff, It shouldn't be too much of a problem. I might still be able to take it back

Just as I'd got the wires in too. Just my lucklaugh



Phil Whitley24/03/2020 17:21:20
1324 forum posts
147 photos

You could use a neutral, but better to get a 440v coil!

Phil, I am back in about an hour!

Johnboy2524/03/2020 17:37:03
259 forum posts
3 photos

Is your lathe single phase or 3 phase? Could you send a photo of the motor info plate?

Johnboy2524/03/2020 17:45:42
259 forum posts
3 photos

Sorry - didn’t see your latest post before hitting ‘send’ button. It’s 3 phase and if you’re in the uk or Europe, it will be 400V.

As Phil said - you could use 230v if you’re got a Neutral on hand in the control box or where it’s fed from but that will need a bit of modification to the wiring.
Again as Phil implied it would be easier to get a 400/440V coil or change the contactor out for a 400V version.


P.S. Don’t use it as it is - you’ll burn the coil out. 😳

P.P.S. Chana are Telemecanique knock off’s.

Edited By Johnboy25 on 24/03/2020 17:47:00

Edited By Johnboy25 on 24/03/2020 17:52:01

Richard Kirkman 124/03/2020 17:55:00
310 forum posts
761 photos

Thanks, Phil and John

Just ordered a 400V one, the one I linked earlier, should be here on Thursday. I'll take the old one out then. Will the wiring be the same as it currently is?

Meanwhile, I've been looking at wiring for the lighting transformer, which seems to be pretty straightforward, but I'll post some pictures in case there's something I can't see is wrong.



Phil Whitley24/03/2020 19:58:48
1324 forum posts
147 photos

Hi Again Richard,

You have ordered a new contactor, good! you can use the existing overload portion, as you probably know, just remove it from the old contactor, and fit to the new one. On the overload, there should be a pair of normally closed connections which is the switch that breaks the holding in circuit if the current becomes to high, probably marked NC with a switch symbol between them. It is pointless to assume that the new contactor will be the same wiring as the old one, so post up a pic when it arrives, and we will do the wiring diagram then.

Good progress, we will get there.

Stay healthy


Phil Whitley24/03/2020 20:15:55
1324 forum posts
147 photos

AAAAAAARGH!!! have you connected the lighting unit to the two slidelock fuses? They will be 415 v or thereabouts! it will evaporate as soon as you put power to it! I assume that the lighting transformer is a 240v led power supply. Remeber that each line of the 3 phase supply is 240v, but between any two lines , due to them being 120 degrees out of phase, there is 415 or thereabouts. You would need (once again) to put a neutral into the machine which means using a 5 pin plug and socket instead of four, and 5 core cable as well. I would mount the transformer externally, plugged into a 13A socket, feed the low voltage into the machine, and use the switch you have fitted to the control panel to switch the output from the transformer to the light fitting.. The transformer originally fitted to these machines had a 415v primary, and 12 and 24v outputs, and some I think were 48V as well.

Lets not have any big bangs eh!


Richard Kirkman 124/03/2020 20:52:05
310 forum posts
761 photos

Thanks, this is exactly why I'm showing it

I still don't want to put an extra plug on, I want it all to run from one cable. But I don't want to put in a neutral in either. Surely this worked once before, so the component must exist. So, where would I be able to get a 415v to 12v transformer?

**LINK** This maybe? A bit expensive

I've made a nice block for the switch to mount to, which is starting to look the part, a few more holes and it'll fit

Didn't get to start on the gaskets, but tomorrow is a new day!

Obviously the transformer won't be used anymore, but I took the pictures before I saw the message




Phil Whitley25/03/2020 14:03:16
1324 forum posts
147 photos

Yes, that transformer would work, but it outputs 12v AC, and you would need DC for an LED, so you would need to convert, to DC, or use some other light source. I always look for the simplest solution! Will see if I can turn anything up.


Phil Whitley25/03/2020 14:22:44
1324 forum posts
147 photos

Maybe this, link

And feed the output to your existing led transformer. Drop an email to RS just to check that it will suit your use, but it looks good to me. Masses of transformers used on ebay!


Richard Kirkman 125/03/2020 15:30:12
310 forum posts
761 photos

Thanks Phil, great to hear

I've just finished the light switch mounting things, so that's looking quite nice, especially considering you'll never see any of it.

I need to order some new belts from Rs anyway so may as well make an order.

What do I really need to ask them, as I still don't really know what I need. This would be preferable as it's cheaper.

Contactor should arrive tomorrow, so I'll start on the gaskets now!

Thanks again


Hopefully this doesn't make you go AAAAAAARGH!!!



Johnboy2525/03/2020 18:53:21
259 forum posts
3 photos

Hi Richard. I agree with ‘Phil on this. 👍


Richard Kirkman 125/03/2020 20:34:47
310 forum posts
761 photos

Little break from electronics, I have started on the gaskets finally. Or disassembly at least...


Definitely not the same colour as when I put it in, I kept reusing the oil to try to flush the headstock a bit, but i still need to get in properly and give it a good scrub


The gearbox was absolutely full of crap, I even found a drill bit in there. There was so much gunk that it was probably reducing the actual amount of oil I could put in significantly.



Not perfect, still needs a good scrub, I've left it covered in degreaser


This was after I'd cleaned it a little, the bottom was full with nutella sludge up to about the top of the black bit with lots of holes in it. So progress has been made. The gasket didn't seem to be in too bad shape, but I'll still replace it.

Contactor should arrive tomorrow so I'll post pictures of that when I get it.

Also, I think the sight glasses could do with being replaced, can't seem to clean them


Richard Kirkman 126/03/2020 11:07:39
310 forum posts
761 photos

Contactor arrived

So, where do I need to stick the wires in?

The overloads will go into the same part as before. but will the motor wires go back into the same L1 L2 L3 as before too?





noel shelley26/03/2020 11:52:17
519 forum posts
14 photos

I saw this thread at the start and have come back. Just a thought, I have a clarkson with lo volt lighting in which the pri is 415v but the sec is 48v ac. I would not be affraid of putting a neutral into the machine ,the extra cost would be a plug. Some inverters (transwave) have 5 pins and it can be a real bonus as cheaper 240v gear can be used. If you wish to use dc lighting ie LED then a dropping resistor if needed to get to the required voltage and a bridge rectifier + capacitor will be cheap and easy in conjunction with the transformer you have . Do not discount incandesant lighting, it avoids the dangers of strobe effect and is cheap, 12v, 24v and 48v bulbs are available.

Good luck, Noel.

Have looked at more of the story. IF you bring in a neutral then an OLD 12v battery charger is just what you need. 3amps or more will do. just put a capacitor across the output to stop flicker. This will drive LED lighting and may even cost 0. Do NOT use a modern charger as many have electronic control that will spoil the game. The mobillity scooter models and sealed Pb gel types will NOT work due to far to clever gubbins also. N

Edited By noel shelley on 26/03/2020 12:13:00

Phil Whitley26/03/2020 12:08:57
1324 forum posts
147 photos

Hi Richard, First off, I am confused!! the terminals 21 &22 should read NO, not NC, but I am hoping this is due to chinese confusion in terminology. put a multimeter across them, there should be no connection until you push the contactor down, if this is the case, they are NO, and have been labeled incorrectly.

Connect the incoming three phases from the rotary switch to L1 L2 and L3 fit the overload to the contactor to T1 T2 and T3, connect the motor wires to the three outputs from the overload

on the contactor, put a wire link betweenA1 (coil connection) and L1.

put a link from A2 (other coil connection) to one of the NC connections on the overload (Need a pic of the overload connections!)

Put a link from the other NC connection on the overload to one of the NO connections on the contactor holding in contacts along with the red wire from the C&D limit switch

Connect the blue wire from the C&D limit switch to the other NO connection on the contactor.

Connect the yellow wire from the C&D limit switch to L3 on the incoming side of the contactor.

With the end cover fitted, and the key switch on, check continuity between L3 and the yellow wire in the C&D limit switch, this confirms that the switches are working.

power up the lathe and lift the stop/ start handle, lathe should start and continue to run.

Press down stop start handle, lathe should stop.

start lathe again and turn off mains power, lathe stops.

turn on mains power, lathe should not restart until stop/start handle is moved to stop position, and then back to start.

This is a peliminary instruction set!! I need to confirm that the contactor connections marked 21/22 are actually NO, and close when the contactor is energised, and also need a pic of the connections on the overload to confirm the connection designations.

BTW! if you get it wrong it will simply not work As long as you have got the coil connections correct!

I need to go lie down for a bit!

If you compare the above instructions with the wiring diagram I did earlier in the thread, you will see they are in compliance.


Edited By Phil Whitley on 26/03/2020 15:23:06

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