Hey all

I am in the process of converting an old PC ATX PSU to a nice looking bench PSU but as I pulled the fan connector from the main circuit board, I didn't know at the time, but the whole connector came away from the board rather than the male plug came out of the female socket!

So, no big deal I appreciate, but this has now meant I am not sure which way the fan pins connect to the board. The pins have remained on the board but the plastic connector has come off meaning I can replace them either way. I am sure this will simply reverse the direction of the brishless motor driving the fan, thus making it suck, or blow!!!

So, my question this very Good Friday to you eminent electronics wizards, is: should a PSU fan suck, or should a PSU fan blow?

Contender for question of the day, eh!

 

Hey all

I am in the process of converting an old PC ATX PSU to a nice looking bench PSU but as I pulled the fan connector from the main circuit board, I didn't know at the time, but the whole connector came away from the board rather than the male plug came out of the female socket!

So, no big deal I appreciate, but this has now meant I am not sure which way the fan pins connect to the board. The pins have remained on the board but the plastic connector has come off meaning I can replace them either way. I am sure this will simply reverse the direction of the brishless motor driving the fan, thus making it suck, or blow!!!

So, my question this very Good Friday to you eminent electronics wizards, is: should a PSU fan suck, or should a PSU fan blow?

Contender for question of the day, eh!

I doubt you can reverse by connecting backwards. A brushless has some circuitry to pulse the coils to make the motor spin. Connecting that circuitry backwards may damage the fan. Fan should be connected with red and black wires so you can know how to connect it.

 

The thing is, I have no way of knowing which way the connector from the fan actually rejoins the board. The pins are still there on the board, but they have come away from the female connector they were attached to, and this is still joined to the male connector on the end of the leads coming from the fan! If you see what I mean

How do I tell which way to put the connector back onto the pins still on the circuit board as it will go on both ways?

 

hi,
Usually the fan sucks air from outside the PSU and blows it internally.
E

 

All atx psu fans suck air in...

 

Cheers Eric and Dave - just the information I was after. Many thanks!

 

Some incidental information: Use your meter to determine which PIN has the positive voltage. That'd be the one you want to put the red wire to when you re-assemble your fan connector. And AFTER it's back on - put a tiny dab of super glue on the board to help hold the plastic body in place so that if ever you have to disconnect it again it's less likely to pull off of the pins.

Positive pin gets the red wire.

The reason why the fan pulls air into the PSU is because it's directed and will cool the switching transistor(s) better than if you pull air out. Pulling air out means it can move toward the fan from any direction inside the PSU.

 

Please allow me to belabor the point a bit. Velocity is used to break the surface layer of air on the transistors. Sucking from all points available does not focus the velocity of the air anyplace. Blowing air right at the hot spots is more effective.

 

Yep, back in the day when I was repairing supplies for a living, there was one which back a couple of times, under warranty, with the power components blown. The factory had fitted the fan the wrong way round. It was about 12" diameter so it wasn't difficult to figure which way the air was going.

 

You may want to fit a filter, especially if you have pets!
Even a coarse one as shown helps.
Check it regularly
Also applies to your PC.

.
Max.