How long must PSU be unplugged before it's safe to open and replace fan?

[PremiumG]

My Cooler Master PSU's fan is on its last leg. I can hear the ball bearings. I've only owned it for about 6 months, but its on 24/7 and I guess the fan just can't take it anymore. I've tried compressed air to clear out the dust but it still sounds like balls rattling around in there.

Maybe i can just oil it?

Anyway, I have replacement 120mm fans. How long must the PSU be unplugged before it's safe to open it and replace the fan?

 

[jonnyGURU]

Gotta PSU tester? I usually plug one in with the PSU unplugged until all of the LED's go out.

 

[Foxery]

In my experience, modern motherboards often have a small green LED to indicate when the board is receiving power. Features like Wake-On-LAN may also draw a tiny amount when the machine is off, but the PSU is on. If your PSU has a hard cut-off switch on the back, these will drain any residual charge left in the capacitors in less than a minute. By the time you unscrew it from the case and pull out the connectors, you should be fine.

 

[bruceb]

All you have to do is unplug the computer from the wall outlet,
then press and hold the Power Switch for a minute or two. That
will discharge 90% of what is in the power pack. As to the fan,
there are 2 ways they can be. Either running off +12V or +5VDC
or more likely off the 120VAC line circuit. Either way, the wires to
the fan are either on push on terminals or a 2 pin connector that
would just unplug. Use some common sense when poking around
and you can change it in about 30 mins at most. Be sure of the
direction of Air Flow when you mount the new fan. They are Marked.

 

[SparkyJJO]

Originally posted by: bruceb
All you have to do is unplug the computer from the wall outlet,
then press and hold the Power Switch for a minute or two. That
will discharge 90% of what is in the power pack. As to the fan,
there are 2 ways they can be. Either running off +12V or +5VDC
or more likely off the 120VAC line circuit. Either way, the wires to
the fan are either on push on terminals or a 2 pin connector that
would just unplug. Use some common sense when poking around
and you can change it in about 30 mins at most. Be sure of the
direction of Air Flow when you mount the new fan. They are Marked.

In a typical PSU I have never seen a 5V fan, or a 120VAC fan. They are all 12V DC fans, may or may use a plug (some are just hardwired to the circuit board, so a new one needs spliced or soldered in).

For discharging, yeah that works. I've been in many PSUs and never gotten hit by doing something similar to that.

 

[bryanl]

Until it briefly whistles, meaning it stops oscillating.

Ball bearings shouldn't be oiled but greased, and use lithium-based grease if you can't completely wash out the old grease, to avoid incompatible greases turning into grit.