head and combo are exactly the same thing, just with a different casing built around them.
Ok, so that means you're on the power board, not the preamp board. R50 is marked on the schematic (page 23) as being ".35, 10W", which means .35 ohms, rated at 10 watts. this should be a big-ass resistor....yeah, this would smoke if something was wrong, its one of the main output ones.
I would check Q13 and Q16 to make sure they haven't blown as well, that would be my first guess as to what went south. I'd also check the assembly around the IC (a 4558) on the bottom of page 23, make sure those resistors are still correct (thats the negative feedback setup I think). After that.....well, the very last thing would be the diodes marked as CR4 and CR10. but those shouldn't be a problem.
If those are fine, put your nose next to the transformer and take a whif. If it smells like toast, then you may have a bad tranny.
I still have the gut feeling that you might have just bridged something accidentally when you were soldering. Look at the diagram on pages 20 and 21, that will show you where there should be bridges and where there shouldnt. Its probably something simple like that.
