Thread: morex psu noise fix

I have a Morex PSU powering my car computer, but i'm not running a MiniITX board (running an i810 based board with an SB Live! and KX Drivers). Ever since i've used the Morex i've noticed a very annoying low pitched ringing noise in my soundcard's output, so yesterday i decided to take a look at the Morex PSU and see what the power regulation on it was like..

The 3.3V line has a couple of Low ESR caps, but it seems that the 5V line (which powers my SB Live! through the PCI) has only one or two small capacitors on it, and it seems like they don't do a very good job of reducing the ripple voltage on the 5V line.

I connected some good quality low ESR caps across the 5V line (Rubycon 220uF ZL series), and there's much less noise now.

I did it in a slightly dodgey way though: There doesn't seem to be any more space on the Morex PCB to solder in additional capacitors, so i soldered 2 Rubycon caps onto a small piece of veroboard and connected them to the 5V line through a 5.25" power splitter, and placed the caps as close to the PCB in the power network as possible. Ideally you would solder them as close to the inductors as possible on the PCB but that's difficult in this situation