ATX continuity between 12V rail and earth

Hi all

Newbie here, getting started on an i3 boxframe. Was working on the ATX (Antec Neo520) as other parts are still to arrive

Cut the connector off the 12V rail, made sure no wires were touching, then connected the green & black terminals on the 24pin plug and turned it on to check they had made a good connection. Fan turned on, was happy, so I turned it off again. Was on for maybe 2 sec.

Soldered the live and ground cables into their groups (also modified one of the MOLEX cables to connect to the 5A connection on the RAMPS). Thought I would check continuity before putting it live- and there is continuity between the live and earth wires!! Disconnected the green/black bridge but it is still showing continuity. Cut all the cables again so they weren't touching, then checked live/ earth again and there was still continuity. About 250 ohm resistance on the multimeter. Pretty sure thats not the way its meant to be so I thought I would check here before possibly frying my ATX or RAMPS

Any thoughts? Or am I just being paranoid? Or have I already ruined it? Didnt smell any thing, or see any smoke. Opened the case and there is white sealant/epoxy stuff on some of the toroids and other components. Cant see anything out of place, so I am guessing it may have been put there on purpose.



Edited 1 time(s). Last edit at 12/25/2014 07:03AM by tim_kberg.

I don't think that you need to worry as long as the resistance you measure doesn't show a real short circuit. I quickly measured the impedance shown between 0 and 12V on two good ATX power supply that I have lying around here - I also got 250 Ohms on one and 120 Ohms on the other.

OK, thanks heaps.

I went back and measured the resistance between two of the live cables and it is 1-2 ohms. Phew.

Merry Christmas