Hobbymat MD65 Electrical Problems

[Steve_MParticipant @steve_m58920]

Hi All,

Got a slight problem with my Hobbymat MD64 lathe in that is stopped working yesterday. It was like I hit the stop button but it wouldn't switch on again.

There was no burning smells and the fuse was still good in the plug. Straight away I conceived myself the motor had gone bang.

After an email exchange with Essel Engineering (very helpful) I removed the motor this morning to check the centrifugal switch to discover this is a later model and doesn’t have one fitted.

So out came the multi-meter and I worked my way through the wiring and the 2 relays.

On the photo below, if I pushed in the white centre contact on the lower of 2 blue relays the motor would run.

 

I’ve check out both relays and they seemed to be working as they should.

Now by luck I was checking the voltage to the on/off switch but my multi-meter was set on ohms/continuity rather than voltage. As I touched one of the terminals on the off switch the lather would fire up and run.

I have now put in a bridge wire from the live terminal too the terminal on the red stop switch as can be seen on the photo below. This is the red wire.

 

In this condition the lathe works as it should using the on, off and direction buttons.

For obvious reason I don’t want to leave the lathe in this condition, I would rather fix it correctly. Problem is for the life of me I can’t work out what I have bridged/by past. In this condition both relays click in and work and my meter checks tell me the switches are ok.

So now I’m confused so hopefully this is where you step in and say that is so & so

Any help is most appreciated

Cheers

Steve

Edited By Steve_M on 31/12/2015 16:09:05

Edited By Steve_M on 31/12/2015 16:10:01

Edited By Steve_M on 31/12/2015 16:10:33

Edited By Steve_M on 31/12/2015 16:11:22

[Steve_MParticipant @steve_m58920]

[martin perman 1Participant @martinperman1]

Steve,

Is the machine fitted with any guard switches or safety switches as one may have either failed or you have a door open for instance which maybe the reason youve bridged a relay, follow the cables you have bridged and one will lead you to the fault.

Martin P

[BazyleParticipant @bazyle]

No real idea how it works as mine pre-dates the invention of the relay.

The stop switch is often a normally closed switch that allows power through to the coil of the relay. When pressed it opens the circuit so that there is no power to the relay, even if the go button or on/off switch what ever is provided is being pressed. Ie total over-ride,. I suspect this switch has failed and is not making proper contact when not pressed.

With all mains unplugged and power switches off can you check continuity through the switch. It may be intermittent. If you usually use it to stop the motor it will be getting the arc from the motor turning off every time so could have burnt the contacts.

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