I assume the answer is yes, but just for kicks I would like to get some feedback on what happened to me over the weekend. Maybe someone else can learn from my mistake.

Over the weekend I rebuilt a power supply/rectifier board for a Bally Harlem Globetrotters. I replaced all 3 header sets, the diodes, and bridge rectifiers per Vid's guide (thanks @vid1900!). With the power supply unit on my bench, I connected AC power to the board and flipped the switch. There was a slight pause before the scene from Back to the Future where the lightning hits the clock tower was re-enacted on my board. Yikes! Much arcing there was to be seen! When I inspected the board, I found that the arcing happened on the back between the 2 sets of diodes that feed the 230VDC circuit. Of course I was to blame due to my shoddy soldering skills. But I could not find anything amiss. I completely inspected everything for solder bridges or things hooked up incorrectly (this board was hacked by many prior operators with multiple wires bypassing the headers). I could not find anything except a dead short between pins 6 and 7 on J2 (this is the AC line in voltage connection). I messed with it some more and completely cleaned it. One thing I found was a glob of conductive grease (at least I think that's what it was since it came off the back of the old bridge rectifiers) that was on the solder side of the board bridging the gap across a couple of traces. I'm not sure if removing this is what did the trick, but after the final cleaning, the dead short on the AC line in was gone. I was able to apply power to the unit and the voltages all check out ok. Weird. I took a smaller glob of the paste and held it between my DMM probes to check for continuity. Seemed like only when the probe tips were really close I could get 80 ohms or so of resistance. Seems to me that this could not be the issue but then again I do not know what the issue could have been... Anyone else ever experience anything like this?

Could have been but the wierdest thing is the dead short across the AC in lines before cleaning off the board. Maybe I also removed a small solder blob while cleaning everything up I guess...

Really digging in here. Found this info on the Arctic Silver 5 site. Interesting that it can act as a capacitor! There was a decent sized glob connecting 2 traces on the solder side of my board. Also, it seems that some pastes/greases are made to conduct electricity. Of course the assumption is that the pinball companies would never use that stuff in production. But, an operator who bypasses the header pins with twisted wires and blows out the solder pads on the rectifier board while replacing the bridge rectifiers, could he be using electrically conductive paste? Who knows?

http://www.arcticsilver.com/as5.htm

Not Electrically Conductive:
Arctic Silver 5 was formulated to conduct heat, not electricity.
(While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)