What brand and model of converter is this? And was it the converter proper that was smoking, or was it perchance something in the electrical distribution panel etc. that is often (but not always) in the same chassis as the converter?
I tend to agree with Scott G in general if it is the actual converter—repair is likely not sensible unless its under warranty. Depending on what died it may well be possible to repair, but unless you can troubleshoot it yourself the cost to do so would likely be not far off from a replacement. Many RVs come with converters from the factory that are not particularly good designs, so a replacement often can be a significant upgrade (faster battery charging, cleaner power, less proclivity to boil batteries dry when on for a long time, etc.)
If it's something in the electrical panel, that's more a wiring problem that needs fixing, and usually repair is quite economically feasible. Replacement breakers or bus bars are readily available if needed (at home centers, electrical supply houses, etc.) and not all that expensive.
