Trouble with my WArco WM240 lathe

[RaceDiagnostics]

I managed to stall it and blow a fuse. No problem I thought, pop in a new one and get back to it. But no, the lathe powered up but the motor wouldn't spin. Started digging inside. It does seem overly complicated for a simple motor driver.

Checked the voltage going to the motor on these two terminal, it was as expected, about 10v to 100v depending on the speed setting.

I thought brushes, so pulled the motor out.

Brushes were good.

Next I tested the motor on a battery charger, it spun just fine. So back to the wiring, checked the fuse in series with the motor, all good.

Then I probed the fuse holder, open circuit!

Took a look inside, the culprit, a burnt terminal!

Stuffed with a bit of tin foil to make better contact with the fuse and I was up and running.

It could have been a lot worse if one of the boards had blown.

Then finished the job of making some wheel locator pegs. No sure if the aluminium ones will be strong enough so made a steel one too.

 

[Kram]

Check the wiring/crimps carefully, a lot of the crimps have the strands folded back over insulation, so contact with the terminal is terrible, and they pull off easily. Fire hazard the way mine was done.

My issues with motor were initially caused by weak brush springs that failed and overheated. Then 6 mo ths or year later, the driver board blew the SCR's. I repaired it, its not the best repair, it does work.

It could have been a lot worse if one of the boards had blown.

I have my old motor and driver board to sell if its any use to you? I dont want much for them, they are in the way. 6 years since I used them but they have been kept dry, indoors.

However it made an enormous improvement replacing the weak DC motor with a huge 6 pole 1.5kw 3ph induction motor and a VFD.