Actually I didn't want to pontificate but I was going to say that it looks like someone studied instrumentation design but forgot basic circuit design.. Someone should tell him that more components don't make the design better..

I think using the upside down design as you put it results in a bit better stability, that is if you know how to do it. If the thing can't foldback lower than 340mA, they didn't know how to do it. In that state you couldn't test a 12 volt 1 watt Zener.

If the design is anything at all like the one posted, I don't see any quick fixes. I could probably redesign it faster. Maybe you should guve that a go. You have a transformer and a box, and apparently two readouts.

I think some of these kits might just be junk. Not too long ago I was asked to look at an old Heath/Bell & Howell scope. It had an intermittently shorted HV cap and a couple of minor porblems, not the least of which is that it had never been aligned. This ain't the first time...

Anyway, it is DC coupled but the sweep generatior doesn't have a split supply, so when you go from external to triggered to freerun the trace needs to be recentered. At first I couldn't believe it, I thought there was something wrong with it buit nope. That is how it works. I've seen them only use short little ramps at higher seep speeds, which I really don't like, but not this before.

Maybe that's where some crappy designs go when they got too much money into them - kits. Then the buyilder thinks he screwed it up and everything is fine. The only problem is if they give the option to send it in for repair, but then someone else gets a crack at it. Business is business.

Seems like you could keep their power transistors and big resistors, take a coupe of your own OP AMPs and make it into something useful.

In the meantime you might want to repost, or I think they call it "top post" this so everyone sees it. SOmeone might have an idea who uses Thunderbird or something to get here. Alot of the oldtimers do.