[thingstodo]

To use my 'video game' or test bench simulator in the basement for testing, I need a motor that will spin at different speeds, driven by the PLC, and the speeds will be ... smooth. I need the rpm that the motor turns to change when I change the output voltage, but be within a few rpm after that change. For example, if the output is 25%, I'd like ... maybe 200 rpm, ranging from 195 to 205 rpm. If the output changes to 50%, I'd like more speed, maybe 350 rpm, ranging from 345 to 355.

So I'm back to the side grinder that I used to test out the maximum encoder rpm earlier. I strapped it back onto the shelving that I am using as a work bench. The side grinder had it's screw-on handle run through a hole in the shelf. That keeps the grinder from rotating, should something go horribly wrong. The grinder is leveled with a small piece of scrap lumber. Two wood clamps are used to hold the grinder to the shelf. Check out the first 2 pictures.

My 24V power supply is rated at 2.1A. Hopefully that's high enough. The grinder is rated for 10A.

Connect 120V to the power supply. There is no output voltage. Disconnect the power and check the fuse. The fuse measures as 1.1 ohms. That seems a bit high? A quick check of the meter shows that using only the probes measures 1.0 ohms .... so the fuse is fine.

Check the input wiring. There are a few strands of wire from the 120V cord that are beginning to fray. Pull them out, strip the cable again and put the newly stripped wires into the terminal blocks and tighten. There is still no output from the power supply.

Drill out the rivets that keep the top cover on the power supply and check the circuit board connections. Ah ... the posts that carry 120V from the power supply board to the transformer are fine. The posts on the secondary of the transformer are not fine. The solder connections from the secondary posts to the power supply board broke.

A quick check with power applied shows confusion. There is no power in or out. So I disconnect the power supply and use some fine sand paper to scratch through the corrosion on the connections - all connections seem to do that over time - until I see shiny metal.

Apply power to the power supply and there is now power going in. There is also power coming out. The transformer is fine, there is 21.6 VAC at the secondary of the transformer. The posts are quite large so my soldering iron (meant for precise heat, to work on electronics) does not have enough power to heat up the post and solder things back together.

Check out the 4rth picture. You can see the gap between the transformer post and the circuit board.

I guess I need a different power supply.