I have an old XPS 400 that I have sitting in a corner as a media server. It works great for that purpose, and I usually leave it on for weeks at a time with no monitor attached.
Recently after trying to reboot the machine, the power button went "mushy"... like some physical component in the switch broke. The system still has power but I have no way to boot it.
I took the front off and tried pressing the lever mechanism attched to the switch directly, but no luck either. It sounds like the typical action is to replace that entire I/O board from the front of the machine, but all I need to do is boot the system *once*, set it to boot after power failure in the BIOS, and all should be great.
This isn't a machine I'm very worried about and it's way out of warranty, so I've been trying to act on some advice I heard which is to (carefully!) short out the particular pins on the I/O connector that tells the mobo to boot. If I could find the pinout information I might be able to do that.
Any advice on (low-cost) actions I can take, or can anyone point me to any pinout information on the I/O connector?
Pinout of the I/O panel is not forthcoming, not posted or given out by Dell any model.
The ATX paperclip grounding of the green wire to black wire with a normally open push button would work.
First, the switch makes momentary contact.
This means that a toggle-type switch will generally not work as a replacement power switch unless it’s also momentary.
Second, the switch is normally open, also known as push-to-make.
When you select a momentary switch, be aware some are normally closed, or push-to-break.
Third, the current carried by the ATX power switch is very low, so you may select almost
any switch you like without regard to the current rating.
This also means you can extend the wires to your power switch using inexpensive hookup wire.
Fourth, the voltage carried is no more than 5V, so you don’t need to pay attention to the voltage rating.
Fifth, the minimum switch you need is SPST (single-pole, single-throw), but any of the other
switch types can be connected to act as a SPST switch, simply by selecting the correct two leads.
|Orange||+3.3 V||1||13||+3.3 V||Orange|
|+3.3 V sense||Brown|
|Orange||+3.3 V||2||14||−12 V||Blue|
|Red||+5 V||4||16||Power on||Green|
|Purple||+5 V standby||9||21||+5 V||Red|
|Yellow||+12 V||10||22||+5 V||Red|
|Yellow||+12 V||11||23||+5 V||Red|
Four wires have special functions:
PS_ON# or Power on is a signal from the motherboard to the power supply. When the line is connected to ground (by the motherboard), the power supply turns on.
Thank you for such detailed information. Forgive me if I make a novice mistake in interpreting it.
I bridged pins 15 and 16 on the connector from the top so that it could remain on the motherboard. It did work somewhat, because the power supply, fans, and CD drive were powered, but the system itself did not boot. I still assume that the mobo needs the switch signal via the I/O cable to actually kick off the boot.
Remember I don't really need to install a switch, but would installing one change my results in any way? It feels like there's still something missing here.
This is a year old post about turn on an ATX supply, so I'm not sure the author is still monitoring this. Seems like good info, but this doesn't work, as stated by a previous posts. This momentary connection of the green to black only turns on the PSU fans for me. It doesn't boot the system. It appears something else is missing. Interesting enough, the author says to use a momentary switch between the green and black (ground) wires, but his video and illustration shows a paperclip inserted for a constant connection, not a momentary connection. So the instructions don't match the demonstration, which is a clue that something has been overlooked in the directions.
Yeah, unfortunately this trick did not work for me. He did say I think that the paperclip would have to be replaced with a momentary connection, but even with the specific switch he suggested I had no luck. I tried some other methods but I eventually messed up the power supply, so I ended up abandoning the project since it was just an old PC I was only using as a media server. The infuriating part is that the PC was fine, the power switch was just over-complicated..