Thanks everyone!
I patched in a D5SBA60 bridge rectifier, and patched in a 5A fast blow (instead of the 6.3A slow blow, those are on the way). There's no longer a short across the mains, the resistance was 340 ohms, and changing. I plug it in and turn it on, and nothing. It still doesn't work. But the fuse doesn't blow, so the diodes definitely were a problem. The main filter cap is a little bulged and maybe should be replaced, but I have other problems to solve first.
There's a relay inline that I don't think is energized, so now I'm digging into the service manual to try to track down why.
https://www.dropbox.com/s/4qjh21sgf9z69d7/hfe_sony_ta-v7_service.pdf?dl=0edit:
I found that R820, the 33ohm 5W slow start? resistor is measuring 120kohms. Maybe some sort of voltage spike on the input fried that. now to bodge in a a couple other power resistors I have to see if that fixes it.
edit2: heck yeah! that fixed it. ordered the right 33ohm resistor, and should be good to go. Now I gotta see if I can figure out why the tuner input is really quiet. The rest work, including the phono, which was the most important