As the title suggests; when connecting the PS_On signal directly to ground in order to switch on an ATX PSU, is there a required amount of resistance?
To try to clarify my particular problem; I have a fully modular ATX PSU (a Seasonic Platinum Series) but am not using it to connect a motherboard, so have no need of the bulky motherboard cable. I decided to order a custom-made cable compatible with the modular connectors on the PSU itself, with a wire connecting PS_On to ground (via a 2-pin header so I can connect a suitable switch or LED if I want). However, when I connect the pin directly, although the PSU switches on, it almost immediately switches off again.
The PSU is not at fault, as connecting the regular motherboard cable using the paper-clip trick works just fine and the PSU starts providing power normally. The only difference I can see between the working and non-working cables is that the non-working cable uses much shorter wires and of a finer gauge (AWG22 at about 5-6cm as opposed to AWG18 at around 60cm). So I'm wondering; is my cable failing to work because of a lack of resistance?
If so, I'd appreciate anyone that can also clarify how I would work out what type of resistor I would need to add to correctly complete the circuit.