Hum from the switching power supply.

[arjepsen]

Hey.
Ever since I got my hands on my d8b and HDR, I've been on a mission to quieting those beast, and have pretty much hacked the living daylights out of them by now.
In the d8b I used a less noisy pc power supply, but wasn't quite happy that I could still hear the fan.
So today I received a new psu to use; a BeQuiet straight power 10. (I know - it's WAY overkill being a 400W psu, but I'm more focused on how much noise it makes...)
Well, it took some hacking slashing and cutting (had to move the transformer and power distribution board, but I got it installed, and that psu is SILENT - I mean I can see the fan moving, but I seriously can not hear it. Great success.

However....
Now I started to notice that there's another part of the whole power supply part that HUMS! I think it's the switching power supply.
Just curious - have any of you guys noticed that in your d8b's???

[anyhorizon]

Most likely the cooling fan over the processor. There's an article I posted ages ago to rectify that which is in the database.

Peter.

[arjepsen]

Thanks for your answer, but that's not it.
I replaced the cpu cooler with an Arctic Cooler silent 3. And I changed the fan on that one to a noctua fan that I run on 7V - even when I put my ear next to that one, I can't hear it!
I quite certain the hum is from the switching powersupply. The system works fine, I'm just worried, since I haven't heard this hum before - but I can't quite figure out whether it was there before, and just got drowned out by the cpu fan, or whether something is not quite right.
That's why I'm asking if any of you guys have experienced hum from that particular part.

[anyhorizon]

Are you talking acoustic hum or hum in the system electronics ? Transformers offer acoustic hum sometimes.

Peter

[arjepsen]

Yeah, it sounds like tranformer hum (I know the sound well, having built several tube guitar amps myself).
But I don't think it comes from the big transformer in the power supply compartment - it seems to come from the cicuitry in front of it. From what I know, there are 3 power supplies in the d8b rack unit, and I believe the hum comes from the "switching power supply" one.

[doktor1360]

Yeah, it sounds like tranformer hum (I know the sound well, having built several tube guitar amps myself).
But I don't think it comes from the big transformer in the power supply compartment - it seems to come from the cicuitry in front of it. From what I know, there are 3 power supplies in the d8b rack unit, and I believe the hum comes from the "switching power supply" one.

If it's an audible 'hum' and it sounds like 60Hz... time for a cap job... those electrolytic filter caps are gonna let go over time, no different than a tube guitar amps hi-voltage supply. I've built a few amps, and repaired many more, in my time. I'm actually quite surprised I haven't to had overhaul my own D8B & HDR's power supply filter caps to date, given the age of the damn things...

However, you knew it was coming, so here it is :
[Standard Mgmt Disclaimer] - "Your Actual Mileage May Vary..."

Peace

[arjepsen]

hmmm... You could be right about the caps.
I'll have to inspect them.

[anyhorizon]

The filtering caps don't make acoustic noise.

Peter

[arjepsen]

Actually, (I think), it's could be possible. To my knowledge, electrolytic caps can actually vibrate.
At least that's what i remember reading somewhere - feel free to correct me if I'm wrong.

[anyhorizon]

I've never experienced it myself, arj, and I'm an electronics junkie. Trannies, yes.

Peter