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Warco wm 250

the lathe part stopped and will nor restart

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Michael Scott 222/02/2021 11:00:55
5 forum posts
2 photos

Eagle eyed people might have seen my first attempt to start a thread. This one is after receiving kind advice.

After some years of great service the lathe part of my wm250 just stopped.

Lots of checking of fuses and limit/cover stops I got me nowhere.

The nice people at Warco sold me a circuit board but after careful ( I think) replacement I still cannot get the lathe to work. I had the variable speed DC motor professionally checked and it is fine.

After the rear fuse blew violently I stopped trying over the winter.

I just repeated the dead short circuit drama

I have not found "smoke" or charring. Nor have I found any loose wires.

I have a photo of the original pcb and there are differences to the new board but I have no way of taking a view on that.

I have the circuit in the IB but the wiring birds nest is a formidable sight for a mechanical engineer especially since I see from other threads that the colour coding is variable. I shudder when I see free floating choc strips. Warco sent me a pcb layout diagram but the lack of reliable colour coding hinders any rational consideration by me.

The question is what do I do next? All suggestions invited!

Is there any one in the Cambridge area that might be able to assist?



David Colwill22/02/2021 12:11:04
737 forum posts
38 photos

Firstly I have no experience of your lathe.

When confronted by confusing wiring diagrams it is often helpful to make a few copies of the diagram that you can take notes on. Then by looking at the obvious things and amending the diagram with things like wire colours, you can reduce the list of unknowns until hopefully they all disappear.

Obviously having someone who has more knowledge is best but this may not be easy in these times.


Andrew Johnston22/02/2021 12:32:59
5969 forum posts
667 photos

PM sent - Andrew

Michael Scott 203/03/2021 09:51:14
5 forum posts
2 photos

Thanks Andrew and for the useful telecon. When Covid allows we will meet.

Bye the way it is a dc brushed motor in my lathe

However as Andrew knows I have discovered a loose red wire hanging below a Siemens block. Pretty obvious the wire has come out of the bottom row of terminals; probably towards the right. I have a photo but cannot yet work out how to include it in this post.

Does anyone with a similar lathe know which terminal on the Siemens block would enjoy being connected the loose wire?


Paul M03/03/2021 10:29:28
55 forum posts
3 photos


I had issues with my VM250 when I first bought it. It wouldn't start sometimes and often juddered with little power.

It turned out to be a faulty Siemens 3TB41 contactor. It comes out easily however I was careful to take as many photos of it (which I no longer have) before removing it. If you have the operators manual there is a wiring diagram on page 21.

It is a process of elimination to work out where each of the wires belongs. It's worth noting that there are 4 rows of connectors with two set back from the front edge. Each is labelled on the front edge. Looking at the wiring diagram only 10 of the 14 connections are used. I stuck labels on each wire as I disconnected them which proved worth the effort.

If you can't sort it out message me and I will try to photo or trace where the wire belongs.

Bo'sun03/03/2021 10:49:20
390 forum posts

Hi Michael,

Paul M mentions referring to the operators manual, which in many cases is probably the correct course of action. Unfortunately, I've found the OM supplied with my WM250 to be pretty useless. It's several iterations out of date, has useful info' missing, and I certainly wouldn't rely on the parts list and accompanying diagrams.

Michael Scott 202/04/2021 16:14:19
5 forum posts
2 photos

Hi every one.

I thought that it might be informative to relate the story of the successful restitution of working status to my lathe.

I apparently In my search for a reason for a lack of power I had lots of advice, one which was that if the little black button on the back would not stay in when pressed i had probably blown the speed control board and duly bought a replacement (ouch) I found out well into my repair saga that this was probably due to the repetitive small cuts I was doing and the resulting back emf being heartily disliked by the dc motor.

In replacing the board and dealing with the Chinese "birds nest" wiring, apart from some unannounced small differences in the pin locations, I found some loose wires. When I sorted that out, with advice form nice people in the forum, and turned the result was a loud exit of the fuse. Obviously a short circuit.

I was really in trouble now!

Happily I have a good friend who was a specialist in designing power supplies for high end cars infotainment systems.

There are plenty of circuit diagrams on the web for very similar boards and after we had done a fair amount of wire tracing he repaired one of the boards and then simulated the board in a freeby app from the net.

With much hope we re-assembled the lathe electronics and pressed the smoke generator.

Nothing!! Sugar

More wire tracing and limit stop checking. Nothing. Then we checked the stop button. Bingo. Another heart stopping purchase; where I found out that the fault we found is common!. Could this have been my original fault!!!???

Another try with the smoke generator button and the lathe ran for a few seconds and then the fuse blew! We calmly (not) considered the situation, looked for evidence of burning and then put in a bigger (much) fuse.


I have now have put a sensible fuse in and I have a working lathe again.

Two reasons for this post. First, thank you to all the people who so kindly received my calls and emails and at least gave me morale support and those who provided real assistance.

Secondly, to give yet another reminder to even the experts that you should check the obvious first. Did I have power at the pcb? No I did not, Why? Mmmmm.....

Keep cuttng metal.


Bo'sun02/04/2021 17:49:49
390 forum posts

Hi Michael,

Glad to hear you're up and cutting metal again. However, I'm sure others will comment. Be sure the fuse is the correct size and not too big to cause something else to fail.

Dave Halford02/04/2021 20:52:00
1388 forum posts
12 photos
Posted by Bo'sun on 02/04/2021 17:49:49:

Hi Michael,

Glad to hear you're up and cutting metal again. However, I'm sure others will comment. Be sure the fuse is the correct size and not too big to cause something else to fail.

Anti surge fuse?

Bo'sun02/04/2021 21:48:50
390 forum posts

Bought an "anti-surge" plug from RS a while ago, (just in case) for my WM250. No idea if it works until it goes (or doesn't) go, tits up.

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