retro games 100 wrote:

I noticed that my Seasonic 380W PSU sounds quieter than my Nexus 350W PSU. Perhaps the Seasonic's fan is of better quality? Then I wondered if it's possible to open up the Nexus PSU, and replace its (12cm) fan, with maybe a Noctua fan as they are whisper quiet? I have never opened up a PSU unit before. Is this something that can be done? There are 8 screws on the section of the PSU closest to the fan, and the presence of these screws seems to indicate that it's possible to access the fan area. Any thoughts please, before I fry myself... 😉

I've done this several times but only with old AT PSU's and Amiga PSU's...you have to be careful to not slip and touch any of the components inside which will give you a nasty shock that might be fatal 😳 so don't drink and switch PSU fan

😁

The more quiet power supply might actually have different temperature control so swapping the fan would be next to useless. You'll also need soldering skills.

I've swapped quite a few PSU fans. It's not a big deal. The risks are that you could make the PSU overheat with a slower fan and that you might shock yourself to death on one of the big capacitors in there. 😀

Just watch what you touch.

You will probably need to solder the new fan wires in, but sometimes they do use a connector that can be made to fit a regular 3pin fan plug. I haven't run into any PWM fanned units, but they are out there. That would require a PWM (4-pin) fan....

So, even if the PSU is safely switched off from the mains supply, it can still be quite hazardous? - a bit like old television sets I believe; the bulky old tube-based ones, that contain some kind of dangerous "coil thing" (technical term 😉 )

They'd discharge after some time. You can also unplug it while the computer is running, that will instantly suck out most of the charge from them.

retro games 100 wrote:

...contain some kind of dangerous "coil thing" (technical term 😉 )

Some CRTs have caps that double nicely as a defibrillator.

rg100 goes and looks up the word "defibrillator"... Ah! 🤣

In the old TVs the picture tube itself is a nice capacitor 😀

I have changed a few PSU fans. Never had header to use a quick swap, but never had to solder either. Always just cut the wires and used butt connectors, heat shrink, and a crimper. Probably could do without the heat shrink if you didn't care about it. As far as discharge, CRT are much worse since the caps in those store thousands of volts, not just your average 110 or 220. Like H-A-L 9000 said, unplugged the AC main while the PSU is operating should do the trick, but if your really paranoid you can use an insulated screwdriver with a grounded copper wire and manually discharge the caps yourself.

> you can use an insulated screwdriver with a grounded copper wire and
> manually discharge the caps yourself.

You can kill it that way...

In the TV only the picture tube has thousands of volts, the other capacitors are your average 250V.

It's supposedly better to short capacitors with resistors to discharge them, but I still think it would be risky (to the health of the PSU) while they're attached to a circuit board.

I would suggest doing the cut-n-splice method that prophase_j mentioned, while being careful not to come in contact with other components of the PSU. Not as pretty, but it's less invasive (you don't have to access the circuit board of the PSU, and you may save yourself some disassembly).

Most fans are in the 5-12 volt range and vary their speed by the input voltage, but some have a 3rd wire (usually yellow I think) that reports speed back to the host device so that it can shut down if the fan burns out.

Also, make sure the replacement fan moves the air in the same direction, as PSU fans are meant to be the main source of airflow in most computer cases. Usually PSU fans exhaust hot air out of the PSU, which causes cool air to be pulled in from the front bottom of the computer case and across all of the components before it reaches the PSU.

I've worked with electronics quite a bit, but I haven't opened many PSUs. The coolest thing I've done with a PSU is jumper some pins in the motherboard connector of an ATX PSU to make it turn on whenever it's plugged in, so that my roommate and I could use it to test a window+LED mod he was making to a 5.25" DVD drive without having to keep installing it into and removing it from his computer.

As for CRTs/TVs, they're usually relatively safe to handle unless you mess with the plunger on the tube. I've opened up a lot of old CRTs to adjust the horizontal output transformer in order to correct for them going dim over time (beyond what could be adjusted for via the front brightness knobs). If I had the guts, I'd play with the convergence rings on the yoke, but I'd rather just buy LCDs to replace most of them instead 😀

Really appreciate all the comments - thanks.