OK, so post pics. Most Epiphone SG's of that vintage were made in Korea by Samick, or in Indonesia. The Korean Samicks are the ones with 2 volume and 2 tone controls. The Indonesian ones were made with 2 different types of tuners, and very different finish on the necks. Now here's the weird part- The fret work and fit and finish is much better on the Korean Samicks, as you would expect, being more expensive, but the pickups suck. The pickups on the Indonesian ones are actually pretty good. Who would've thunk? There are also the newer Prophecy line. One model has an ebony fretboard and Gibson dirty fingers pickups. The other model has EMG-81's and a rosewood fretboard. I don't know where they are made, but they look like a step up. It also looks like they figured out that their pickups suck.
The Indonesian ones, you have to go through about 20 of them to find one with no major build defects, but if you find one, it can be OK as an expendable travel axe. Or- at the right price point, you can cannibalize it for its pickups.
The Korean models also have quality control issues, (although not as bad) so you still have to look at them very closely, but the better of them are actually pretty damn good guitars. However,they really need a set of pickups. Replace the pups on one of the good ones with classic 57's or burstbuckers, or whatever you like, and they can really rock. I had one that I switched out for single coils that I used mostly for playing The Who, and it was a lovely guitar. Of course, because it's an Epi, it gets no respect. If you can't take that, and you think guitar image matters, give it up and get a Gibson.
Show me pictures, and maybe I'll tell you more.-Richie
