Loss of power

My lathe stuttered to a stop and the display light went out. I instinctively pressed the green button on the stop/start switch. The display momentarily lit and the chuck turned until I released the green button. I also noticed an interference noise on my radio as I held in the green button. I repeated with the same result. I tried for a third time and everything was dead. No display light etc. I am no electrician but jumped to the conclusion that the stop/start switch had failed. I ordered and fitted a new stop/start switch but this made no difference. I also changed the machine fuse, 13 amp plug fuse and checked for power to the 13 amp socket. I have no idea what is causing my loss of power to both the display and lathe motor. Any help or suggestions would be greatly appreciated.

Best Regards Steve Rowe, North Staffs, UK

Hello Steve

That does sound like a dodgy no-voltage-release-relay, but this may not be built into the switch itself.

You can download a manual here:

chestermachinetools.forumchitchat.com/post/db8-db8vs-manual-7112463

P.24 shows the NVR relay built into the switch though.

It doesn't sound like a fault with the inverter as the chuck is turning when the switch is pressed.

Is it possible that one of the safety interlock switches is not properly closing?

Hi Neil. Thanks for your reply. The chuck did turn and the display lit when I pressed the green button but now I have nothing, no turn and no light. Hard to explain as when the problem started the display panel lit and chuck turned only momentary when I held the button in, I also heard interference on the radio as if something was arching. Now I have nothing at all working, including the display. Thanks for you time.

Best Regards Steve

Steve - Make and model of lathe please?

Rik

And would I be right if I guessed your lathe is fitted with a DC variable speed motor?

Edited By Rik Shaw on 10/11/2016 09:55:02

Hi Rik

Chester DB8VS Lathe.

It has variable speed control.

Thanks Steve

If the information in the link that Neil provided is correct  then the motor is three phase with a VFD. Disconnect the wires from terminals 5 & 7 on the NVR switch.(Mark them.) Connect a mains voltage lamp to terminals 5 & 7 on the NVR switch. Check that the fuse has not blown. I would guess that it is on the panel behind the NVR switch. If not you will have to look for it. It it has blown it may be because the NVR switch was arcing. If it has blown replace it .(It only needs to large enough to power the bulb at this point. Test to see if the lamp goes on and off when the start and stop buttons are pressed. Reports the results.

Les.

Edited By Les Jones 1 on 10/11/2016 12:02:09

Edited By Les Jones 1 on 10/11/2016 12:03:16

Steve - Les is the expert in the sparks department but just in case it IS a DC motor with speed controller as is my lathe (WARCO 250 V-F) I also have suffered similar probs. I see you have checked the machine fuse but are you sure there are not more fuses? Mine has two and both of these have popped at various times (but not lately).

If your speed control board has failed it will give similar results to those you are experiencing. I am already on board number three with the lathe about four years old. With an out of warranty machine my last board was in the region of £110 which hurt!

With this type of motor / speed control board layout it pays to follow WARCO's advice as follows:

Only ever power up the motor with the speed control set at minimum, only then should you turn the speed up. Before powering the motor down you should also reduce the speed to minimum.

In the (approx) year since I began following WARCO,s advice I have not had a problem.

The above advice also applies to my WARCO WM16 variable speed milling machine. Since I began applying this advice to the mill as well following yet another failed speed control board on it I have had nil problems.

Sorry I have to restrict myself to personal experiences only but I am fairly brainless in the 'lectrric dept.

Rik

Edited By Rik Shaw on 10/11/2016 12:42:59

Hi I have just re read the first post and realise that Neil's links were just for an example. We are waisting our time until Steve tells us what kind of lathe we are talking about. Ignor my last post as I made a false assumption.

Les.

.

Just like it says in the sub-title

Thanks Michael and Rik for pointing out that the information was there all the time. Apologies to Steve for thinking that he had not given enough information. So the suggestions I made in my post at 12:01 on 10/11/16 are valid.

Les.

Hi All

PROBLEM SOLVED........

I don't have a mains test lamp but do have a multi meter.

I attempted to test the NVR switch and was not able to pick up any Voltage on any terminals.

I then searched for a point to pick up V and looked at the re fuse holder.

Bingo. The rear of the fuse holder was loose and I found this had been the cause of the arching.

I now just need to acquire a new fuse holder.

THANKS to all of your help.

Best Regards Steve Rowe