Honey I blew up the mini lathe speed control board

[HankMcSpank]

Hi Irving - tks for the clarification!

Have you any schematic links for the full wave controlled bridge you mention? I'm hopeful there's nothing majorly wrong here, as there's no 'toast' or anything melted (whereas, the original board I spoke of when I bought was absolutely nuked!)

Ok, the board was riveted to that metal surround (as were those SCRs and diodes for heatsinking)- drilled the rivets out - alas, a good few components underneath. I have my first 'lead' though. There's a small 78L08 regulator on the top side of the board ....it is *very* hot (you can see it in the photo I posted aboe - to the left of the piccie next to R33). The DC voltage on its input pin is near 10V...output pin is just 2V! It could be something on it's output dragging the voltage down (hence it getting hot) down so I'll remove it from circuit & see if it checks out. Alas I don't have an 8V regulator handy if it is this ......just 20p from Farnell (but minimum order of £20!)



(a couple of LM324s and one LM339 you see there)

Edit: Ok, i whipped thAT 78L08 out - boshed it into a breadboard that I already have in place with a 16V unregulated DC as an input- it literally smoked! (which suggests it was flakey as a 16V input it should be able to handle - http://www.datasheetcatalog.org/data...INGS/78L08.pdf ). Ok, so I'll need to source a replacement now!