The Home Machinist!

Looks like the transformer was designed for 220 or 380VAC input and has a 24,30 and32 VAC outputs. The schematics shows that you need the 24VAC and to choose between 30 or 32VAC.

Interesting enough also is that the picture of the electronics show that the 30VAC was chosen and the schematics show the 32VAC was chosen.

I installed two transformers to replace one, in a friends lathe so he could sell it. It was from Australia. He had already had the motor rewound for use in the USA. It will be easy enough for you to get replacement transformers also. You may get it done with one, or it may take two. I have not looked to see what is available.

I think you should scrap it, I would be happy to come take it away for you......Just kidding:)
It sounds like an oddball transformer, but with some searching around hopefully you can find one...or two...to replace it.

if all else fails, you can replace the transformer with 110 VAC in and 24 VAC out and change the motor starters to use similar coil voltage, which may not even be necessary...and have a separate 110 vac plug for the control circuit.

There is nothing in the circuitry that won't run just fine on 24VAC except the two contactors.

The 30 and 32VAC outputs of the transformer goes through a rectifier and feed the magnetic clutches, that change the speed of the spindle, by way of a joy stick on the apron. I suspect that the clutches want a 24VDC input, which would require about 30 to 32 VAC to get there. I also suspect that the reason that there is a choice, between 30 or 32VAC depends on the actual level of the line voltage. There is also a timer that I believe creates a very slight pause as the machine changes gears, so no two gears are ever engaged at the same time.These are just my best guess, from the schematics and speaking with Harold about his machine.
Harold's has a two speed motor, which he ordered with the machine when he bought it, new in the 60's. A single speed motor machine, has 8 speeds with back gear(4Hi/4Lo). Harolds has 16. There are six clutches, 4 for speed and 2 for spindle direction. Harold's machine has lost the low speed clutch, so if you decide to scrap it, he would be interested in it for parts.
Although, if nothing else is wrong with it, it should be easy enough to get running. You can install a transformer for each, required voltage, if necessary. PM for a number, if you want to talk about it.

It sounds easy enough; transformer, rectifier, 24VDC.

Unless one of those clutch coils has fused and caused the problem.
Is there a fuse after the transformer?
If not, you should add one. And you could check the resistance of the various clutch and solenoid coils too, look for signs like blackening of wires / terminals.

I’m just starting to sort this out. Now that l see the schematic it makes more sense. Mine is different than the ones pictured. Still trying to locate the rectifier...

Interesting!
Indications are that your machine has a two speed motor, which is not common for the Sag 12. I had to special order mine, which delayed shipment by several months.

I don't see a (selenium) rectifier, which I suspect is a requirement for the clutch operation. Makes me wonder if, maybe, it has been replaced by a solid state device.
Early in the operation of my Sag 12, I had a rectifier fail. It was replaced with another, so my machine still has one.

It's possible that you may not have to worry about the 30 or 32 volt supply if your machine is using a solid state rectifier. There's a substantial voltage drop when seleniums are used. That would not be the case with solid state.

The joy stick on later models has a push button on the end, which is used for a brake. My machine is not so equipped. Is yours?

If you decide you've had enough and do not wish to pursue the repair, I'd like the opportunity to buy your machine. Patio made it clear, it would be nice to have for parts, as they are no longer available. It's going to get more and more difficult to keep these old relics operational.

H

parts were available in italy last time i was tagging along with a friend (5 years ago)

If you can not find an OEM replacement go for a generic control transformer of equivalent capacity. If you can't get one to fit the original space buy an enclosed control transformer and mount it externally.

That electric system looks like a whole fun weekend just waiting to happen.

When I worked on Harold's cylindrical grinder, I found all the AC wire was one color and the DC wiring was another. Different machine, different time, but it may be a clue that will help.

Ok, Answers....
I have not been able to locate the rectifier.
The joy stick does have the button on the end.
The motor is a two speed, controlled by two buttons on the front panel.
Not sure about fuses, cuz I have had no schematic until now. There are obvious blown fuses. The wiring is making more sense now.
If you look closely at the pics the burning on the transformer is obvious.
I don't know the difference between the contractors and the clutch solenoids. (yet)
I'll try to find some time to get deeper into this, this weekend, I would like to get this thing working again, its a nice machine. However it the cost/time and complexity get to much I'll consider the sell option (Harold)
I have another lathe.