Looks like one of these:
http://www.tvhistory.tv/1948-Admiral-7845.JPG
I really like that basketweave cabinet.
Most likely an old paper cap popped. You could also have one or more shorted electrolytics which cooked the 5U4 rectifier tube until it popped.
Hopefully, none of the hard to replace components fried. I strongly recommend you at least replace the electrolytics and any visible fried paper cps before trying to power it up again. Better yet, replace all the old paper caps. Some of the micas could be bad too.