Question Running a PSU without a motherboard

[PingSpike]

I'm basically building a ripper box full of old DVD drives and was just going to use an old ATX PSU to power them. I know you can just connect a black to the green wire to turn on, but does it work with a momentary switch or does the connection need to remain on the entire time its running? Haven't used this trick in forever.

 

[TheELF]

I always used a paper clip that was left in forever.

 

[sdifox]

https://www.electronics-tutorials.ws/blog/convert-atx-psu-to-bench-supply.html

 

[aigomorla]

Directly switching the psu via green wire needs a latching switch.

Although you can use this, its called a jbod adapter from supermicro, and it will turn it into a momentary switch compatible.

Supermicro CSE-PTJBOD-CB1 JBOD Power Board - DIY JBOD Chassis Made Easy

The $30 Supermicro CSE-PTJBOD-CB1 JBOD power board helps turn a standard computer chassis into a DIY JBOD chassis.

www.servethehome.com

 

[mindless1]

Depending on # of drives and concurrent use states, you may find that an old group regulated PSU has a problem with the two very different states, spinning discs to use more 12V current, then idle using only 5V. If it were only one or the other state you could just put a dummy load on the less/un-loaded voltage rail but in this case you may have to experiment with loads on both and measure the current.

If it is not very many drives, do you even need a separate PSU? I mean if you're ripping it has to go to a host system anyway, with its own PSU, and it may have plenty of 12V & 5V reserve capacity to power a few DVD drives.

 

[PingSpike]

Depending on # of drives and concurrent use states, you may find that an old group regulated PSU has a problem with the two very different states, spinning discs to use more 12V current, then idle using only 5V. If it were only one or the other state you could just put a dummy load on the less/un-loaded voltage rail but in this case you may have to experiment with loads on both and measure the current.

If it is not very many drives, do you even need a separate PSU? I mean if you're ripping it has to go to a host system anyway, with its own PSU, and it may have plenty of 12V & 5V reserve capacity to power a few DVD drives.

Most of that is a bit over my head. I have few old PSUs I'm doing nothing with at the moment. I think the newest is probably from 2012 or something.

I suppose the number of drives will be between 4 and 8. I want keep them external to the machine they'll run off as its kind of full/busy instead already and is an on all the time server. They will connect by USB 3.0 so the whole mess can be turned off when not in use.

 

[mindless1]

Okay, doesn't hurt to just try it in simplest form, may work fine like that, just keep in mind that you could end up needing a load on a lesser used rail if the PSU shuts down under certain mixed loads, and it could require a multimeter to measure which voltage feed is the issue.

You wrote USB3 though, if they are in enclosures with integrated 12V to 5V step down power so only use a barrel socket 12V input, you'll need adapters for that and then the issue is only if the 5V rail needs a dummy load to draw some current. Usually 1 amp is enough (5 ohm, 10W (being conservative)) resistor on 5V rail in that case, but again you could start off without it and just try that if it seems necessary because the PSU is shutting down.

 

[mindless1]

I always used a paper clip that was left in forever.

That, or a scrap of wire, OR, with some old motherboards I go crazy with a blow torch outside...

Heat the back of the motherboard with a torch then wack it against a metal tub, and all the soldered on components fly off easily. Might take a trial or two to get the timing right to not melt connectors and not catch the PCB on fire (which REALLY stinks) but is pretty quick and easy to do.

Off pops the PSU connector, then you can solder the green/black corresponding pins together with a piece of wire and have that to plug into ATX PSUs to turn them on.

The chips and capacitors I usually toss when using a torch removal method but other connectors like the 12V CPU, are also useful for powering 12V things that need more current than a single molex 4 pin or SATA connector can provide. That connector would also be handy to use to make a dongle with several barrel plugs if the aforementioned USB DVD drives only need 12V input.