two power supplies both show red

My console was showing three flashing lights and the power supply had a red light when I tried to switch the xbox on. I followed the trubleshooting guide online by checking the cables, trying different sockets in the house, letting it cool down and blowing
any dust out of it but none of that worked and I concluded that the power supply was bust. So I went out and bought another power supply to replace it. However, when I got back and tried it out it didn't make a difference. With both power supplies I get the
same thing, a short, high pitch whistle (lasting less than a second) then the light on the PSU goes red and I get 3 flashing lights on the front of the xbox. Can anyone help?

:)

 

Power Brick failure.

Power Supplies don't usually make humming noises. If your Power Supply is in a non-ventilated area it will overheat and the temperature will raise, the Power Supply may show a red light and your console may show 3 flashing red lights or no light at all.
if you encounter 3 red lights try the Flashing Lights Solution, if you encounter no power try the No Power Solution. If the Flashing Lights Solution or the No Power Solution doesn't solve your problem your Power Supply will need to be replaced.

 

Power supplies

[quote user="Attusuzzar"]

I have a 360 arcade and the AC adapter turns itself off every now and then and the light on it goes red, it also often makes quite a loud noise. I'm thinking of getting a new adapter but I don't know if it will matter if I get a 150 watt adapter like I have
now, or a 175 watt adapter.

Any help would be very appreciated.

[/quote]

Check the light on your power supply:

Solid green or solid orange light: Your power supply is working. If your console won’t turn on, try our Xbox No Power Solution.

Flashing orange, solid red, or no light: Your power supply may need to be replaced. Try the following solutions:

1. Try plugging your console’s power supply into a different electrical outlet. Do not use a surge protector.
   
2. If the power supply light is solid red or flashing orange, unplug the power supply and let it cool for 30 minutes. Then, plug the power supply back into the outlet.
   

If your power supply light is still flashing orange, solid red, or unlit, your power supply needs to be replaced. You can Order a replacement Xbox
360 power supply from our Xbox Online Service Center. Console registration is required to replace the power supply under warranty (the power supply warranty is the same as your console warranty).

 

Where did you purchase the new power supply from? If it's not an official power supply for the console that could be causing the issue.

However, if it does not work you may need to set up a repair for your console.

 

I bought it from a second hand games shop. It seems pretty legit and has Microsoft written on the back.

 

Sounds like the used power supply may be broken as well. Are you using a power bar to plug them in? If so, try plugging them in to a wall socket.

Otherwise, as I said before, the system may be in need of repair.