anyone good with lathes?

[Sidewinder]

Right, OK , there was no mention of a clutch.

Not all M400’s have a brake and clutch.

So basically there is a switch or contactor which applies power to the PSU which in turn then energises the brake coil, power to release.

Or, the PSU is always under power and the switch/contactor allows power from the PSU to the brake coil?

 

[revjames]

Sidey, its been a huge learning curve. I found out today that its been playing up for ages. I have discovered that the 73v ac supply from the transformer at the top centre of the panel supplies the psu via the yellow cables. The blue cables seem to be the contacts to initiate the DC.  The AC supply is on the psu as soon as the lathe is switched on. However the Dc side only activates when brake needs to be released. Looks like main smoothing cap (470 uF 160vdc) hasnt been working for quite some time resulting in a lower output voltage to the coil which has resulted in the brake dragging. Coil is now cooked and it seems a rewind is the only option. 

 

[Sidewinder]

ΟΚ so the modern equivalents to that brake are 24V DC, 103.5 V DC, or 207 V DC.

Based on your 73 V DC, RMS, I presume you have measured that with a multi meter (DMM, not MFT).

Then Root 2 x 73 = 103.238.

This would be near your rectified and smoothed DC output.

The cap should be easy to get, RS, Farnell, CPC, Rapid, Reichelt, Arrow, Mouser, Digi-Key.

There is also a suplier that is trade ONLY, to the motor rewind/repair industry that does a massive range of start/run caps.

If you are not a rewinder, you need to be introduced to them by one or they won’t sell to you!

I’d look at changing the rectifier too at this point because with the coil gone, the cap gone, that is going to have been stressed significantly I believe, and will be the next thing to pop.

 

[Sidewinder]

Roughly what OD is the body of the brake coil Rev?

 

[revjames]

Roughly what OD is the body of the brake coil Rev?

inside diameter would be approx 4" outside about 6" I would say

 

[Sidewinder]

inside diameter would be approx 4" outside about 6" I would say

View attachment 10851

Is there any model or other info apart from the Warner electric bit on the terminal box?

 

[Sidewinder]

OK, the current version of that is 43W @ 103.5V DC it would be a 35Nm model.

 

[revjames]

Is there any model or other info apart from the Warner electric bit on the terminal box?

no nothing else. 

 

[revjames]

OK, the current version of that is 43W @ 103.5V DC it would be a 35Nm model.

excellent. thanks how did you arrive at that figure by calcs or have you found info for that machine?

 

[Sidewinder]

By looking at the physical dimensions of that unit and comparing them, the voltages you provided and the physical size, to that of the current product, then checking the data sheet for the current model.

 

[revjames]

to start with I was getting about 68vdc. I found a manual which gave the procedure for setting up the brake but gave no coil specs. The PSU is supposed to be variable, turn up voltage pot until brake releases, note voltage, turn up 6v more then lock the pot. Unfortunately, after replacing the cap and a burned resistor, the voltage has increased to about 107vdc but will not vary on the potentiometer. My electronics knowledge is limited but reckon it must be a transistor.

 

[Geoff1946]

What are you using as a load?  It probably won't control if open circuit.

 

[revjames]

What are you using as a load?  It probably won't control if open circuit.

Thanks Geoff, I was wondering if there needed to be a load on it. Perhaps a 110v lamp or something.