Good Day all,

I have two motor controllers, one from a pottery wheel and one from a semi-industrial sewing machine. Both are still commercially available so it's not an emergency to repair these but I am interested in learning more about them and how they have failed but only have basic electrical training from technical school.

The first board, from a pottery wheel, I can troubleshoot it just past the supply components. The 110V comes into the circuit on the lower left corner of the board through a three pin connector. There is a 10A fuse immediately after, followed by a 0.1 microfarad "suppression" capacitor (not sure if suppression is correct or not but I read it while looking online), then more capacitors I cannot identify, a transformer, resistor, and the power then goes out to the board components. There are two larges caps and a few smaller ones and none of them appear to have leaked out or popped. They tested correctly on my fluke, but that was testing while on the board, do I need to remove them for correct testing? On the right side there are a number of IGBTs which I assume are for the motor outputs but I don't know.

The second board from the sewing machine, seems more simple and I already got a bit of help on it. When i bought the machine it blew fuses immediately. Speaking with a distributor they had me check the rectifier and FET which were both bad. I replaced them and got the board to start powering on without popping the fuse but it doesn't provide the proper output so they have simply told me to "replace the board or upgrade the system". Again I can identify the majority of the basic components but not much past that.

Is there any sort of flow chart/cheat sheet for the order of operations for checking through a board to verify components? Are there components which have to be desoldered from the board to be correctly checked? Any advice would be appreciated.

 

Welcome to AAC!

You have two separate problems and each deserves its own thread.

Pick one problem (they both look equally complex) and lets run with that first.

 

For any motor controller, the first step to check is any and all power semi's afixed to the heat sink,
Then go from there. May involve a little reverse-engineering.

 

Welcome to AAC!

You have two separate problems and each deserves its own thread.

Pick one problem (they both look equally complex) and lets run with that first.

Fair enough. I made it one thread because I was looking for general help looking, but splitting them up for specificity makes sense.

Would you suggest deleting this one and making two others or editing this one to be the pottery wheel and another new one for the sewing machine?

 

Fair enough. I made it one thread because I was looking for general help looking, but splitting them up for specificity makes sense.

Would you suggest deleting this one and making two others or editing this one to be the pottery wheel and another new one for the sewing machine?

No. Stay on this thread and keep this one for the pottery wheel. Don't start a second thread until we are done with this one.

 

Right on.

So buddy ended up buying a new control board for the wheel and the new board does the same thing. No response to power on whatsoever. I tried bypassing the input breaker to make sure it wasn't somehow jammed open internally and then checked the connector going to the board from the breaker with a meter and found it has 120VAC when measured between the connector pin and ground. The board is getting power supplied to it but something is still not right.

With a brand new board I am now thinking it must be something else. The rest of the system connecting to the main board is as follows.
Inputs
1. Power from the breaker
2. Forward/reverse single pole double throw selector
3. Connection to the foot pedal (Speed setting)
Outputs
1. Power to the motor
Unknown
-2 small connectors coming out of the motor opposite of the power inputs. Not sure if they input or output ie. a speed feedback or excitation voltage for the windings.

I reached out to the manufacturer asking for troubleshooting ideas or how to bench test the motor. We'll see what they say, or if they even get back to me.

Any ideas?