PS2: Can I use a 5v smoke unit w/ a 3v Board?

I would say yes but send us the item number of your train first. I have a challenger that had a 5 volt board and only had to change to a ps2 3 volt board but youll have to change the connectors 3 volt board connectors are white and 5 volt board connectors are black.

so if your 3 volt board has white connectors pull them off and replace with the black connectors form the 5 volt boards electrically they are wired exactly the same as far as I know! the harnesses wont plug in to the white connectors all the way, that's why you need to replace with black connectors!

ps I'm also into turntables send me an email if you want too!

YES.  All PS-2 and PS-3 smoke unit are interchangeable.  The only quirk is for the small smoke unit with single element.  It still has an equivalent resistance of 8 ohms, but it is a single element and MTH modifies the flash code to reduce current to the smoke unit.

Otherwise, 5V versus 3V versus PS-3 does not matter.  2 16 ohm resistors that give you an equivalent reading of 8 ohms.  G

Thank you for the responses! I always appreciate the help I receive here. I have successfully rebuilt the 4014 Premier 3v PS2 Big Boy Smoke Unit with a spare 5v smoker. It puffs great now. Just found some cold solders in the tether receiver that I need to handle soon as I have a new fine soldering tip, but otherwise she's running great!

When you're tinkering with the tether, keep in mind that ANY short between wires or to the frame is very likely to take out your PS/2 board, so be careful and check your work!