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2 PSUs, 2 different problems

Ruiner

Ruiner

2[H]4U
Joined
Aug 22, 2000
Messages
3,093
I've an Antec Phantom 350 in my HTPC and isolated a low level hiss/static from the analog output of my sound card to it (the PSU). (tried the usual suspects, muting mic and other inputs, turning off power saving options in bios).

So I swapped in an older Antec 350 Smartpower....no more hiss, but it has different problem. Sleep mode is broken. Trigger it and instead there is a cold power off reboot. Also, this PSU exhibits coil whine in shut down mode, unless the switch on the back is flipped off.

Any suggestions to fix either or both units?
 
Both units seem to have substandard caps from the pictures I can find. Bad caps could be the issue with the static from the first unit.

The second unit may just not have the standby capacity required for your unit. Thus the high load coil whine while off and no standby issue.

This is completely conjecture though. I could be completely incorrect. Both units seem kinda crap in build quality. You may just want to pickup a nicer lowend unit. CX430 from Corsair would likely be perfect for ya.
 
Thanks for the leads anyway. I put chokes on the audio out cables and on the molex that feeds the sound card, but it didn't help any.
This PSU has served me well, it's probably time to replace it. The other was just a spare that came with a case I bought years ago.
 
Bah. The CX430 I sourced did the same thing. Took the mobo out to test bench and problem is gone (even with the old Phantom) which means a case/ground/accessory issue. My bad for throwing hardware at an issue before completely diagnosing, but I wonder why the Smartpower didn't do that.
 
Ruiner said:
Bah. The CX430 I sourced did the same thing. Took the mobo out to test bench and problem is gone (even with the old Phantom) which means a case/ground/accessory issue. My bad for throwing hardware at an issue before completely diagnosing, but I wonder why the Smartpower didn't do that.
Click to expand...
Are there any reviews with oscilloscope photos of the noise output from each voltage rail?

How about putting insulating washers on top and bottom of each mounting hole? If there's any change in audio noise, even if it becomes worse, then you know that ground loops are involved.
 
Pull the power cables from your ODD, HDD, and other accessories. You might have something producing ground noise. You might just have ground noise on your house wiring. When you tested with the second PSU did you actually mount it, or just plug it all in and leave it outside the case?
 
Jorona said:
When you tested with the second PSU did you actually mount it, or just plug it all in and leave it outside the case?
Click to expand...

Tested the Corsair in the case. Tested the mobo, bare except for sound card (xonar hdav) with phantom. I'm guessing ground loop involving mobo.
 
larrymoencurly said:
Are there any reviews with oscilloscope photos of the noise output from each voltage rail?

How about putting insulating washers on top and bottom of each mounting hole? If there's any change in audio noise, even if it becomes worse, then you know that ground loops are involved.
Click to expand...

None that I know of. I'll try the washers.
 
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