Thanks very much for the info. I know it takes patience to explain things to persons uneducated in your field. I have simlar problems on the mechanical end.
I think I understand why the resistor is perhaps not a good choice. If I understand it correctly, the higher voltage available to the motor when it is not drawing 4A might cause it to overheat. I can get my brain around that idea. The motor actually draws 20A max, presumably when stalled . . . which is how I cooked the little 9A PS . . I had the lock on the indexer and started the program running. I was wondering for a few seconds why the indxer was not spinning until after the flash of light on the shelf over my head . . . and everything went dead
![Roll Eyes ::)](https://www.machsupport.com/forum/Smileys/default/rolleyes.gif)
The power supply I just bought is listed as unregulated. http://www.kelinginc.net/SwitchingPowerSupply.html It is Model KL7220
Can't say if it is 'linear' because I do not know what that means relative to a power supply. What is 'toroidal' by the way? I know what the word means, but as with 'linear' I can't relate that to a power supply in any way that seems logical.
![Embarrassed :-[](https://www.machsupport.com/forum/Smileys/default/embarrassed.gif)
So there is still the option of a step down transformer. If I found a transformer that halves voltage and is rated to carry 20A @ 36V on the output, (or 10A 72V input, I suppose), would that be suitable for running the little servo off the big 72V supply?
OR . . . venturing farthur into the swamp . . to tap the transfomer where the voltage is 36V? I have no idea if this is a reasonable idea, but it makes sense to pose the question as long as you guys remain willing to tollerate me pestering you.