The actual opto is through hole but the rest of the components are not.
As this is the second opto board fault mentioned in this thread I am assuming that this opto board has only been made for AC/DC and either they have a bad batch of transistors or some one stuffed up and specified a transistor that is not right for this application. 
Time will tell.
And they must have a really crappy batch of #89 flash lamps. I had to replace 6 of them because they were blown.
At least they were all easy to get to.
Don't get me wrong, I am not knocking Stern, we don't live in a perfect world.
Maybe they bought 10,000 transistors at $0.001c each instead of $0.002C each also? Bad batch or sourcing cheapest possible parts?... only Stern know.
Is this Caveys machine??? If so it was the only one on the forum that hadnt had SOMETHING wrong with it...
