Myford ML7 motor wiring

Hi Ian,
I would expect 3 to show continuity to A in the forward position of the switch. Can you double check if this is the case. If it is not the case then I suspect that the switch is faulty. If it is the case it should be possible to get the switch to work but it will only provide single pole isolation of the run winding. (If it was used for reversing a 3 phase motor then it would isolate all 3 phases in the centre off position.)  In one of the pictures of the switch there is a short grey wire linking two terminals. The right hand terminal is 1 (I think) Which terminal is the other end connected to ? In the picture they both seem to be in the same angular position which does not make sense as the 6 terminals appear to be at 45 deg, 90 deg, 135 deg, 225 deg, 270 deg, and 315 deg.

Les.

Edited By Les Jones 1 on 23/09/2014 22:29:19

Hi Les.

I will check the switch position tonight.

The link in the photo is below, in line with terminal 1 looking from the back of the switch and is not marked.

Ian.

Hi Ian,
So there are 7 terminals on the switch. (Or are there even more ?)

Les.

Hi Les.

No more just the 7

Ian.

Hi Les.

C - 3 when the switch is in reverse.

In the diagram showing the connections that run in forward and reverse, in both cases the switch is in the forward position.

Ian

Hi Ian,
If terminal 3 does not show continuity to any other terminal in the forward position then I think the switch is faulty.

Les.

Hi Les.

I could take the switch apart but I would like to know what to expect.

If I open it and lots of bits fly out I wont be able to use the lathe at all., I've not seen any pics on line so I might have to get a new switch. I'll give it some thought.

Thanks Les.

Ian.

Hi Ian,
Like you I have never seen one of these switches and would be cautious about taking it apart. I don' suppose that you live anywhere near me ? If you do I could have a look at it sometime. If you gave an rough idea in your profile of your location there might be someone near enough to offer help.

Les.

Hi Les.

I live in Dorchester, Dorset.

A long way from some of the model shows I'd like to visit.

Ian.

Too far away from me Ian !

Hi Les.

Not a problem, I'll find away round it.

Ian.

Hi Ian,
Here is one possibility if it can be made to fit physically. Here is the electrical data on this range of switches.

Les.

Hi Ian,
I have been looking at the way the switch works. There must be 5 contact sets. Each contact set is on a layer of the switch. I will call the front layer layer 1. Terminals C, 3, and A are actually connected to 2 layers each. (You can see the metal connections from 2 adjacent layers bent together.) Terminal C goes to layers 1 & 2. Terminal 3 goes to layers 2 & 3. Terminal A goes to layers 3 & 4. The contact that I expected to be closed in the for forward position of the switch (Terminals 3 and A) must be the contact set on layer 3 Are you sure that the screws in terminals A and terminal 3 were tight when you did the test. If not there may not have been a connection the layer contacts. I would suggest repeating the test with all the terminal screws tight.

Les.

Hi Les, Thanks for the information. I will re check the terminals this afternoon.

Ian

Hi Les

The contacts A-3 had an intermittent connection.

I took the switch apart and the connection between A & 3 is now good.

Ian

Hi Ian,
This is how I suggest connecting the switch /motor.

1 Start winding Motor terminal R (Red wire ??)
2 Live in
3 Start winding Motor terminal S (White wire ??)
A Live in
B Run winding Motor terminal U1
C Run winding Motor terminal U2 Also neutral in.

Note live in goes to 2 terminals. Also neutral AND U2 connects to terminal C

This is on the assumption that the only continuity between the switch terminals are the ones that you originally listed plus 3 to A in forward and C to 3 in reverse.

This is how I understand the switch works.

Forward B to 2, C to 1, A to 3

Reverse B to 2, C to 3, A to 1

I think there were some errors in your original tables of connection and I cannot see on the picture of the motor terminals which colours go to U1 & U2 (I think it is blue and green but I do not know which way round.)

If you find forward and reverse are the wrong way round then swap over the wires that go to S & R or U1 & U2 (BUT NOT BOTH)

By the way when I was looking closely at the pictures of the switch to try to understand how it worked I noticed it was made by "Santon" NOT Stanton.

If you took any pictured of the disassembled switch I would be interested in seeing them.

Les.

Edited By Les Jones 1 on 27/09/2014 14:37:36

Edited By Les Jones 1 on 27/09/2014 14:38:30

Hi Les,

Thanks for the list of connections, I hope to try them later today.

I do have some photos, only one of them is in focus. I will reduce them and put them on the post.

Ian.

Hi Ian,
I will PM you with my email address so you can attach the picture files to an email.

Les.

Hi Les,

I went back to the motor and found one of the black cables should have been S and not U2. As labeled in the terminal box.

Then following your connections it all worked. Forward and Reverse, wonderful .

Thank you Les.

I'll send the photos tomorrow when I will be able to reduce their size.

Ian.

Hi Ian,
I have sent you a PM with my email address so you can just email the pictures if that is easier. What did you have to do to fix the intermittent contact set between terminals 3 and A ? It's nice to now it's all working. The OP that started this thread did not have the manners to post the outcome of his problem. I would even prefer it he came back complaining that we all gave him rubbish advice.

Les.