Take a look at the site of littlemachineshop.com. IIRC they sell
replacements for these speed controllers for these lathes and the
mini-mills, but I think they also have some info on circuit diagrams as
well. Look under the resources button on their site. They also sell the
mosfets (get the part number from there) and the troubleshooting info may
track the fault back to other than the parts you suspect.


Do a google search for "Mini-mill speed controller repair" or "mini-lathe
circuit diagram". I know that I have seen the diagrams for these boards
floating about the web.

Cheers
Trevor Jones

Excellent link, Trevor, looks like they have the beast for $120 and there is
someone in the States who repairs them for £25 plus bits.

I might try repairing, but apart from a pair of power transistors there are
a couple of ICs. One reason I am slightly cautious about poking round with a
DVM or scope is that the board is fairly tight and with 240 V on it rather
than the more normal 12 or 15 it could be easy to fry something by accident.
Will also try the other links, thanks all for the suggestions.