I have a milling machine with power feed on the table. The drive controller has failed and parts are like hens teeth. I want to use an Arduino to control the speed. The field and armature are in series I think to compensate for the varying load as the feed travels across the work. The input power is 120VAC with a 110VDC60 cycle motor. The AC is fused at 4A. I need to use the switches and Pot to signal the Arduino for output. I am asuming the 60 cycles for the motor is half phase AC.
REally bad assumption. The field and armature are in series to produce what is called a "universal motor" that will operate correctly on EITHER 120 VAC or 120 VDC.
The schematic shows an SCR speed control. Replace the SCR and the other diodes and your speed controller will be back in business.
OR you can buy any AC speed controller and use it in place of the original.
Thanks for the response. That was my original plan.
The "bracket" that holds the motor and gearing is also where the POT and switches mount. The circuit board is cracked so I'll have to do it on a perf board. I have no idea what the values of the diodes are, the markings are illegible. The diac is unavailable as far as I can find. I think a NTE5635 will work for the triac but has a different form factor. Any Ideas on replacement parts?
I did that before I decided the SCR was bad along with another diode on the board. Having the switches and POT mounted on the board make for a difficult installation in the housing. Probably why the board was cracked in the first place. I think it will be a lot easier to work on if I just build a module and mount it and the controls separately.
I'm not sure how to wire that and keep the reversing feature of the switches. It would also defeat the purpose of the fast traverse switch. Maybe I can use the components from an external power supply in place of the original circuit board.
This controller uses novel bi-directional high-power SCR. It can be very convenient adjust the current up to 25A, and solve the over current problem of the heating wire resistance is too small in the case of cooling causing good.
It's almost an achievement. I love how it's on track to begin, then descends, like the translator reasons that people never read through the whole thing anyway.
