Honey I blew up the mini lathe speed control board

[HankMcSpank]

Ok, my replacement 78L08 arrived - just slapped on it in. Now there's 8V on it's output, but when I connect my lathe spindle up to the board - instead of not turning at all - t's going at full tilt now (ie speed control has gone), which to me suggests that maybe an SCR is short? (ie rather than being gated, it's 'on' all the time?).

Else I guess it could be the SCR 'gating' waveform up the swanny. I'm figuring the gate voltage on these SCRs is relatively low voltage scopeable with a 10X probe? (My USB scope spec is 35V input max)

Edit: Ok, whipped one of the SCRs out & it checks out a little strange...

(that's a german datasheet, hence the K for cathode!)

A quick refresher on how to test these puppies is here...

http://www.allaboutcircuits.com/vol_3/chpt_7/5.html

which suggests the only low reading I should get is between the cathode & gate (& in one way only?) - well I'm getting 45 ohms between the cathode & gate with DVM probes connected either way.

Also these SCRs are getting quite warm without a load being connected - methinks they might be duff too - will order some up.