Electronic speed controller fault

[sjedwards053]

I have a Charnwood W824 which has been performing brilliantly. Yesterday it suddenly decided to operate at half speed only. On the lower gear ratio it will only operate from around 250 to 1000 rpm as opposed to 450 to 1500. On the higher ratio it will only go from 500 to 1500 instead of approx 1200 to 3500. Obviously something has gone funny in the electronics of the speed controller. Does any body have any idea which area of the electronics I should start looking at.

 

[Spectric]

Based on this

https://charnwood.net/product/variable-speed-control-for-w824-midi-lathe/
I would suggest it is an issue as they sell the complete unit but maybe repairable, they would prefer you not to fix it. Can you take the cover off and take some pictures, might just give an idea of how it ticks.

 

[Sideways]

It's described as having a 550W DC motor, but it's obviously a brushed motor and they are also known as "universal" because they can be run on AC or DC alike. It's the same basic type of motor as in your electric drill or your scalextric car. The commutator sorts it all out.
In the 550W electric drill, the variable speed control is a tiny module built into the trigger.

The point here is that if you open up the box with the speed control, you may well find a simple module built onto the back of the speed control knob. Chances are good that you can replace that with one bought from ebay for under £20. You will be looking for an SCR or Thyristor variable speed controller and they can be had, cheaply, in power ratings much bigger than 550W.

 

[Richard_C]

Speed controller is most likely and the suggestions above are good. But, check your power supply first, free and simple. My Coronet Herald was behaving erratically on startup and when dialing in more speed and I suspected the speed controller, but by chance I was at the Midland Woodworking Show and mentioned it to an RP rep. He said they didn't much like extension leads and just a bit of voltage drop could cause problems. I went home and reorganised my workshop wiring, what's plugged in to what, and it's been fine since. Your Charwood shouldn't draw much current but still worth a look before you spend money.