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Warco WM250v VFD. Start problem.

Fault with machine looking for advice

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Hill Ruyter20/08/2017 18:18:25
2 forum posts

i have a WM250v (the one with the VFD) that has been working fine for several months.

Recently it started intermittently refusing to start. The main fan is running fine and if I toggle the direction to off, open the gear guard or toggle the spindle guard micro switch the fan slows so it is ot these switches

The problem is intermittent but getting more frequent when I hit the green 'go' button nothing happens I can hear the relay trigger it the spindle does not start when I hit stop and then start again it may or may not start

Eventually I can get it to start and works fine for that operation the next operation is pot luck if it will start

Very recently (yesterday) it has started stopping the spindle while turning the spindle with stop and start on its own until I cycle the red and green then I am back to pot luck if it starts

Anyone have any experience of this fault I am assuming there is some safety mechanism or sensor that is playing up but don't want to open the machine up without an idea what to look for

All help welcome

SillyOldDuffer20/08/2017 18:50:07
7234 forum posts
1595 photos

Sounds like a loose wire.

Not sure about a 250V (I have a 280), but on mine taking the back off the control box lets me see the VFD LED display. If it's showing an Error Code, that should point you in the right direction. No error code is good news.

From what you've said, probably not the Mains power or Motor connections.

Could be a intermittent safety interlock switch. On my lathe the chuck cover came loose on the switch spindle so the micro-switch inside didn't get quite enough leverage. Removing the chuck guard and manually moving the spindle into position should prove this. The other switches seem less likely to develop a mechanical fault.

Another possibility is that one of the various screw terminals inside has come loose. There are several on the VFD and contactor and perhaps more behind the control box. Worth gently waggling them about and re-tightening. I can't say where they all are on a 250, I expect one of the experts will comment.


Hill Ruyter20/08/2017 21:24:23
2 forum posts

Thanks for the pointers.

I'm pretty certain it's not the chuck cover switch as the fan slows when this is switched off

I'll open up the front and check the screw terminals as you suggest.

Sam Longley 128/04/2020 20:01:44
843 forum posts
30 photos

I know that this is an old thread, but has anyone else had this ? Same model lathe.

Did you ever find the problem, because mine has been doing this for ages, but it is now getting worse, requiring it to be switched on off for up to 6 times on ocassions. There is a loud click when the green button is pressed. Other times it starts OK. But it has now begun to stop whilst turning. Even when doing quite light cuts. I have permanently removed the gear cover & byepassed that interlock. (wired it with a plug & adjustable stop for threading on the carriage).The chuck guard has been removed & I have rotated the bar as far as it will go so I do not believe it is the locks.

Unfortunately the lathe is against the wall & bolted on the cabinet & then to steel supports ( to raise it 9 inches) then bolted to the floor. So to get to the back is going to be a major job to get it off the base then off the cabinet etc. It would be handy to have some idea what to expect before beginning.

Was it just a loose connection? I have looked using a mirror & cannot see one


not done it yet28/04/2020 22:42:40
5948 forum posts
20 photos

I would not rely on only turning any bar to check a micro-switch operation. I would at least be checking the resistance of the switch for consistency of operation if it cannot be accessed and short circuited (as a practical test).

not done it yet28/04/2020 22:42:42
5948 forum posts
20 photos

I would not rely on only turning any bar to check a micro-switch operation. I would at least be checking the resistance of the switch for consistency of operation if it cannot be accessed and short circuited (as a practical test).

Steve Dunthorne 112/07/2020 12:52:09
21 forum posts

I have a 2007 WM250 which has just gone wrong this weekend. If I press the ON button, the motor turns on, and speed control works too, but if I release the button, it will not remain latched on. I unbolted the front panel,so the button panel was loose in my hand, and tried this again. I notice the KEDU KJD17B NVR (no volts release) switch buzzes when I press ON in a rather loud and unusual manner. It certainly is not latching either. This switch is a 5 pin switch which is readily available on Amazon for about £18. I have ordered one for next week.

Of course, the 5th pin is provided a latching mains signal and this comes via all the interlocks etc, but the fact it buzzes so much must mean there is power to the solenoid, and yet it still is not latching, so I suspect the switch is failed internally.

I will happily report back when I get the replacement fitted. I hope that may be of interest to other owners.

Steve Dunthorne 114/07/2020 17:18:52
21 forum posts

Doesn't look like a lot of interest, but I promised....

Replaced switch and all good. Only thing was, as soon as I unplugged the wires from the original switch it became immediately apparent the fifth wire (the solenoid drive wire) had NEVER been attached to its slip-on connector plug, never crimped, just loosely sitting in the plug, so for thirteen years, this had just been on the cusp of working.

Old switch was fine after all.

No worries, one of those things.

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