Brent
If you have the wrong synch speed, you won't get underexposure and color shift. You'll get part of the image exposed. For example, if your PC connection only takes 1/60 for a synch speed and you shoot at 1/125 you should see about 1/2 the image exposed perfectly (assuming all else is correct) and the other half BLACK. No exposure. Amazing how these devices work!
I've screwed up the synch speed at least twice. Once on my M645 where the synch speed is 1/60 I had the dial set to 1/125 and didn't notice -- untill I got the film back! On the other, the manual said synch to 1/250 -- but that was the internal flash and the manufacturer's units. The external flash (studio strobes) were only good at 1/125. Again, 1/2 of every frame was exposed.
If you're getting underexposure and color shift, it could be your flash units. Perhaps they're not putting out the amount of light you think they are. If there is a problem with the electrical system and they're not getting proper power, that could also account for low output.
Best of luck.
Bob
Something from my studio:
