John,
Here is a picture of the controller taken off it's heat sink. There are two SCR's and three diodes in the middle of them. (I'm pretty sure they are diodes as they are labeled D506, D507 and D508 and only have two wires, but looking at it closer I see they use to have three wires and one wire was clipped off.) They say 071-0039 on them and a D2, but that doesn't seem to reference anything when I try to google it. I'm guessing Miniark has their own label on them so you have to go to them for replacements. The two outer "diodes" read shorted on a meter, and the middle one tests as a diode should, no reading one way and around 650 ohms the other direction. Having the two outer ones read a dead short makes me think they are at fault. They are right inline where the power enters the board too.
On the back I see four diodes in a bridge rectifier formation, but they seem too small for the motor and must be for the signal transformer to convert AC to DC for the circuit on back. I tested all of the diodes and they all seem fine as well as the two small diodes next to the input transformer on the top side of the board.
I'm going to order a new controller this week, but would also like to repair this one for a spare. Hopefully I can find some replacement parts for a reasonable price.
I would be very interested to know how to add a transient suppressor to the main input as sometimes the motor kicks in hard when first started and it blows my GFI outlet.
Milton, I will take a look into the reading you suggested. I also work with aluminum 99% of the time, but thought it would be cool to use the G96 code and run like the big machines. I have been reading the Mach 3 manual a lot lately and see there are a ton of features that would be neat to use. Hopefully I can figure out how to get some of them to work!
Dale P.