need help on computer power supply noise

[rambo99]

My son has two computer power supply which he remove from the case and transfer them to a bigger case each power supply are not Join together one power supply is for one car amplifier and the other power supply for the other Ampliifer all the 12v wire are join together for amp load and GND for each power supply both power supply working OK for the two Car Amplifier the only thing he found was noise from the Amplifier output.
Is the because the power supply was remove from there case in to a bigger case

The yellow wire are not join with the two power supply
power supply number 1 yellow wire are together for 12v for one Amplifier
power supply number 2 yellow wire are together for 12v for other Amplifier

We found the problem with your help the board was not GND on the Secondary side to the case and all noise has Stop

 

[Timescope]

I would advise you to put the power supplies back in their original cases.The case is specially designed to cool the supply and also acts as a screen to prevent electrical noise generated by the supply from being radiated.
Do not join the +12v (yellow) wires from the two supplies together because the two supplies will try to "fight" each other to control the output voltage.
Connect all the GND wires from the power supplies and amplifiers together at one point .

Timescope.

 

[Rleo6965]

The way I understand the question was that his son have 2 computer power supply and 2 amplifier. He installed the power supplies in each amplifier as 2 separate unit.

I assume that power supply still use its metal casing and still have the cooling fan. So there will no problem with ventilation and electrical noise emitted by psu circuit.

I think the cause of problem was that the electrical ground wire of psu casing was not connected to amplifier electrical ground. If the noise from amplifier was humming sound or 60 hertz frequency then its the electrical ground was not connect together.