DC motor controllers

There is discussion on this NG periodically about using DC motors on a wood lathe, and then there are discussions about controllers - a friend and I got a big pile of controllers a week ago, and I'm starting to sort through them. There are working ones, non-working ones that are repairable, and a "non-repairable" VFD that would be great if it only works. You can get information on these controllers from

- the manuals are on-line. And, you can ask me questions if you like. The "repairable" ones are the best deal if you are willing to tackle the electronics, otherwise, the working ones would be your best bet. The RG300 and 500 series would be good choices, the MM would be really nice for a pen turning lathe or a smaller tool. All of these adjust speed with a 10K pot, so they are very easy to hook up. Most are bi-directional - set the pot in the middle for off, turn one way for forward, the other way for reverse. most can be configured to turn one way only, and can have separate speed adjustments for each way (all this is explained in the on-line manuals)

I've tested the pile I brought home with me, here is what works and some prices. Note that I didn't do a full factory test, I connected power and a small (.2 amp) DC gear motor and made sure that the controller would operate the motor properly. It is possible that there are subtle problems that this qauick test wouldn't pick up, but at least it separates the "repairable" from the working.

The following work MM22000A - 0ne availalbe $35 RG300U - one available, $48 RG51U - one available, $25 RG500UA - one available, $55

The following don't work, but are in my opinion repairable - they produce field voltage (if applicable) but don't drive the motor properly: MMRGD10-230AC (this is a very cool controller, if it worked, I replaced the SCRs, but it's still inop) $12 RG300UA - missing a couple of 2K resistors so I can't complete the test $15 Mystery controller (Minarik), similar to the RG500, but a bit larger, no heatsink, digital speed select. three of these $8 ea, one missing some SCRs (that I used on the RG10D above) and some other parts $2 XA970207 - I suspect the diode bridge, will experiment later $12 MAC03 series AC controller, missing a capacitor, a resistor, and a transistor - very nice VFD (if it works), $18

The following doesn't work and is probably not repairable, but may be good for parts MAC08 series, no heatsink, missing a capacitor, a several surface mounted parts exploded. this is an AC VFD, the CPU is probably OK, the power light operates like it should, but I'm not going to try and replace the surface mount parts. This would be useful if you have another MAC08 series drive (it is not the PWM variant of this drive). $4