No power detected SATA power socket, but powers on hard disk without issue

[branded]

Hello,



I appreciate it's a weird title. Let me explain.


So I've made a few arcade machines using PCs and to light up the LED buttons, I use a SATA to Molex adaptor and connect the LEDs to the yellow (12v) and black ground cables. This has always worked fine.



This time, however, I'm using an old HP all-in-one (AIO - PC built into a monitor) and using the same method does not light up the LEDs. I have tested the exact same molex-LED apparatus on a normal desktop PC and it works fine, but not in this AIO. To make sure the SATA power is working on the AIO, I connect a HDD to it and it powers on and runs fine. Not only does it not work when I connect the LED apparatus to it, but testing the SATA power socket with a multimeter shows no power coming from it.



The only explanation for this is that the AIO only provides power to the SATA power socket if there is something plugged in to the *data* socket as well. Maybe this is some power saving feature, since it has a small PSU built into it? All power saving options on the BIOS have also been disabled.



Can anyone shed some light on this and how I could get around the issue? I want to avoid using a separate 12V power adaptor, since I want to LEDs to power on when I power on the AIO PC.



Much appreciated!

[lilshawn]

I've encountered separated ground rails from time to time.

IE: where the 12v line has a specific wire for ground/negative and the 5v has a specific ground/negative. if you try and use the 5v ground for 12v it doesn't work and vice versa. i have no idea why they do that, as most of the time the grounds are attached together on the device... but it might be to keep from people using 3rd party devices/coolers/pumps/adapters etc. on the computer and killing the power supply (as they often run them razer thin on their capabilities.).

[Zebidee]

Can anyone shed some light on this and how I could get around the issue? I want to avoid using a separate 12V power adaptor, since I want to LEDs to power on when I power on the AIO PC.

There are a few ways to get a separate 12v adaptor to come on at the same time as your PC.

Easiest is to use MASTER/SLAVE power strip/board. These will have a "MASTER" outlet, which you use for the PC. Then plug your 12v adaptor into a "SLAVE" outlet. The MASTER only activates the SLAVE outlets once a minimum amount of current flows. This means in practice that you can power-on the entire unit with a single press of the soft power button on the PC. Prices vary wildly, cost probably around $20-$80.

Here are some I found quickly by searching for "power strip master slave".

https://www.ozstock.com.au/9336/Energy-Saving-6-Outlet-MasterSlave-Power-Board-with-Surge-Protector.html?id=9336
http://www.doss.com.au/doss2016/product/33540300/
https://www.amazon.com.au/Schwabe-Multiple-Sockets-Earthing-Contact/dp/B01I3IP6WM
https://www.audiophonics.fr/en/multiplug-power-distribution/master-slave-1-5-port-schuko-power-strip-black-p-15673.html


A slightly more complicated, but cheaper, way to manage this is with a relay, which cost ~$1-$10. Put it on the active power line. The relay is switched, to pass current, when it detects a DC voltage (typically 5-12v). The relay itself draws very little current as only needs to detect the voltage. Of course, the catch is that you still need to get some DC voltage from the PC for the switching, but you could easily get 5v from USB (cut up an old cable, there are 4 wires: typically red is 5v and black is GND; green/white are data, you can just cut them off).