Xbox 360 with ATX PSU - Always On?

[yellowsnow4free]

Hey everyone!

So after spending way too much time trying to mod the original PSU on my Falcon Xbox 360, I decided to run an ATX PSU instead :P

I'm using an old 250 W Hipro PSU that I got out of a free desktop computer (currently tearing it down for parts).

I followed this wiring method:



I got the transistor and resistor (15k I think) from the Xbox 360 PSU.

I haven't had much time to test it, but it appears to be working fine.  However, the PSU seems to always be on.  The moment I plug it into the Xbox 360 the green power light is on, and the PSU fan is also running.  I still need to test if plugging in the PSU to the outlet, but not into the Xbox 360 powers it on or not.

I think it's because this PSU doesn't have a standby mode, like the original Xbox 360 PSU and some (newer?) ATX PSUs have.

Question 1: Even though I wired it with the proper transistor and resistor, is my PSU always on because it doesn't support standby mode?

This guy's PSU works perfectly:

http://youtu.be/uWd4NOPv7EY

Unfortunately, my PSU doesn't have a power off switch, so I'd have to wire one in.

Question 2: To add a switch to my PSU, I would have to wire it between the green wire (PS_ON) and a black wire (ground), right?  If I add a switch, is there any reason I should keep the resistor and transistor hooked up?  I don't want to harm my PSU or my Xbox 360.

Thanks!

EDIT

I found this video on YouTube and it confirms exactly what I'd like my Xbox 360 PSU to do:

http://youtu.be/SYuDe-oMh3U

Notice how the moment he presses the power button the 360 the PSU fan kicks on.  I'll have to check, but when I tried this last night the PSU fan was on immediately after plugging it into my 360.  In the video description (even though it isn't in English) I did find a wiring diagram:

http://i.imgur.com/zq1bdhJ.png

Looks to be the same as mine, although I'm using a 15k resistor instead of a 100k one (I used the one that came in my 360 PSU).

Is this simply how my PSU operates?  I'd prefer not to have the PSU running all the time.

[Rodent]

all you would be doing is cutting the power on and off  by adding a switch to the green and black wire shown   I am not positive but the transistor and the resistor would be needed so that you would have 5volts on stand by  and i am sure its there for a reason .

[yellowsnow4free]

all you would be doing is cutting the power on and off  by adding a switch to the green and black wire shown I am not positive but the transistor and the resistor would be needed so that you would have 5volts on stand by  and i am sure its there for a reason.

Thanks for the reply

I'm trying to figure out if my PSU supports standby mode (like the PSU in the video above).  I was really hoping the PSU light and fan wouldn't come on until I pressed the power button on the 360, but then again the 360 does draw 5v even when it's off, so maybe it's working correctly?

Researching online isn't helping much, because it looks like this mod is really popular outside the USA, so most results aren't in English :P

I'm thinking the best way to add a switch would be to the green and black wires, but after the transistor and resistor, just to allow for 5vsb through the Xbox.

But I'm still researching.

[RDC]

If it's an ATX PSU it has a 'standby mode' which is really just everything is off inside there but the 5vsb line. When PS_ON is grounded the PSU turns on, when it's not grounded the PSU is off, aka in standby.

Make sure you have the EBC wiring correct on your Transistor.

You should also have another Resistor from the Base to Emitter (roughly 10 times what your Base Resistor value is, so ~150k) so the Transistor will turn off when it's not being biased to turn on.

[yellowsnow4free]

If it's an ATX PSU it has a 'standby mode' which is really just everything is off inside there but the 5vsb line. When PS_ON is grounded the PSU turns on, when it's not grounded the PSU is off, aka in standby.

Make sure you have the EBC wiring correct on your Transistor.

You should also have another Resistor from the Base to Emitter (roughly 10 times what your Base Resistor value is, so ~150k) so the Transistor will turn off when it's not being biased to turn on.

Thanks for the prompt reply

I have a 15k resistor wired in between the blue wire (coming from the 360) and the base of the transistor (I pulled the resistor from the 360 PSU as well; it looked like it was being used to power it on).

I've been doing some digging and it looks like most people online recommend using a 100k resistor for this mod.  Like you said, maybe I'm not dropping the voltage enough, and the PSU thinks the 360 is already on?

Luckily I've got a 100k resistor that I got from the old 360 PSU

[RDC]

The Base Resistor is a current limiter. The one you need to connect between the Base and Emitter will make sure the Transistor cuts off.

If you're just snagging random parts, are you sure the Transistor is an NPN type? and that it's even good?

[yellowsnow4free]

The Base Resistor is a current limiter. The one you need to connect between the Base and Emitter will make sure the Transistor cuts off.

If you're just snagging random parts, are you sure the Transistor is an NPN type? and that it's even good?

Yeah, I just did another test last night and the PSU powers on without being plugged into the Xbox 360, so my transistor / resistor aren't correct.

I grabbed the transistor and resistor from the Xbox 360 PSU (both were part of the PS_ON system) so I assumed they'd work, but I'll go with the RadioShack parts in the diagram above.

Unfortunately I realized the 250w PSU doesn't have enough power on the 12v rail, so I started to swap it out with a spare (free) 400w PSU I got, but it appears to be DOA -_-

[RDC]

Assuming with electronics is a good way to damage something at best, or yourself at worst if it explodes from being connected someplace that it shouldn't be, and that's why parts, have part numbers.

[yellowsnow4free]

Assuming with electronics is a good way to damage something at best, or yourself at worst if it explodes from being connected someplace that it shouldn't be, and that's why parts, have part numbers.

For sure

I actually looked up the transistor that came off the Xbox 360 PSU online, and I thought it was a replacement for the transistor in the picture above.

I did a little more testing, and it seems like the 360 transistor worked in the opposite way that I wanted; it would power on when plugged into the wall, then power off when I plugged in the 360.

Lesson learned though; luckily it just shutoff the PSU instead of harming anything :P