What do the specifications for your motors say?Holy cow!
I must me learning something here. That is the type of transformer I have been looking at. I just wasn't sure the 10amp would be enough. Do you think that one transformer would be enough sarge. From what I have gathered through the information posted here, it should be plenty....right?
I think that by using that 24VAC 10A transformer, you should at least be able to step one motor at a time. What I don't know is the holding current that the other two will require simultaneously.
Remember, the original transformer was rated 5kVA, and this one is rated 240VA. It appears they were running a lot more than just three steppers and three drivers from it.
Since the supply was unregulated, having massive overkill in the supply pretty much guarantees that the output will remain within a fairly narrow range.
I have no way of knowing how much current your steppers actually require, except for in the schematic there were 20A fuses on both sides of the bridge for your three steppers/drivers combination - so that pegs the current limit down.
You might find that a single transformer is sufficient to run one, or maybe even all three steppers.
Since these transformers are pretty cheap, I think I'd get one per stepper/driver combination, and use a bridge rectifier, cap, and bleeder resistor for each.