ghost power supply buzz?
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ghost power supply buzz?
the power supply to my soundcraft ghost (CPS 275, the beefier one) has developed quite a buzz. there isn't much in there, and the buzz is coming from the large transformer (big fucking coil) inside. it begins as soon as i power up, and stays around no matter what working condition, as long as it's on. i'm in a smaller control room now than i used to be, but i don't remember this PS making any noise in my old place (had the board for about 4 years). further, where it buzzes constantly now, it used to be quiet when powered up and develop the buzz after it had been on awhile.
so for you ghost users/smart electronics people out there, how can i clean this thing up? i don't hear it in the audio path at all, just directly from my rack where the power supply sits. but it is loud enough that is has become really annoying.
any ideas?
so for you ghost users/smart electronics people out there, how can i clean this thing up? i don't hear it in the audio path at all, just directly from my rack where the power supply sits. but it is loud enough that is has become really annoying.
any ideas?
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roger that.
i'm fairly savvy with electronics myself, and was hoping when i opened the box up that a simple physical vibration from something loose would be the issue, it isn't.
there is a big transformer inside, and it's buzzing like mad. i can't isolate or dampen it, this coil itself is buzzing.
this unit has a fan, and the buzz is like 4 times louder than the fan. the fan i can live with, the buzz not so much...
i'm fairly savvy with electronics myself, and was hoping when i opened the box up that a simple physical vibration from something loose would be the issue, it isn't.
there is a big transformer inside, and it's buzzing like mad. i can't isolate or dampen it, this coil itself is buzzing.
this unit has a fan, and the buzz is like 4 times louder than the fan. the fan i can live with, the buzz not so much...
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- buyin' a studio
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ok, quick question. there appear to be two, one on the +17v system, and another on the 48v for the phantom power. scodiddly, in your experience, is it one over the other that usually goes out? and is there any way to isolate which one is problematic, or should i just change out both. hell, i don't even use the phantom power from my board, do i even need the 48v side?
hmmm...
hmmm...
Re:
I’m having what seems like the same issue with my power supply (CPS-275), and I’m wondering if you ever discovered a solution. Did replacing the bridge rectifiers help?dwelle wrote: ↑Sun Feb 20, 2011 7:30 pmroger that.
i'm fairly savvy with electronics myself, and was hoping when i opened the box up that a simple physical vibration from something loose would be the issue, it isn't.
there is a big transformer inside, and it's buzzing like mad. i can't isolate or dampen it, this coil itself is buzzing.
this unit has a fan, and the buzz is like 4 times louder than the fan. the fan i can live with, the buzz not so much...
I’m not too savvy myself, but I did open things up to track down the location of the sound, and it was certainly the transformer. With the console disconnected, the unit runs quietly, but when connected, the buzzing is present. I checked that it was secured well to the case to make sure it wasn’t a physical vibration.
I took the unit down to the local electronics repair shop to have them inspect it and asked about the rectifiers. They looked it over and weren’t able to find anything wrong. Unfortunately I wasn’t able to bring the console down, so they weren’t able to run it with the load connected.
Incidentally, I did replace the fan with a unit that was recommended in another post (Noctua NF-A8 FLX). That has made a big difference, but now I notice the buzzing even more
- Scodiddly
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Re: ghost power supply buzz?
The bridge rectifiers are going bad.
That's the problem, even if they don't yet measure obviously bad.
I've done a few of these.
That's the problem, even if they don't yet measure obviously bad.
I've done a few of these.
Re: ghost power supply buzz?
Success!
I just swapped out the bridge rectifiers tonight, and the buzz is essentially gone. Hardly audible if I put my ear right next to the transformer.
Incidentally, there were two different rectifiers in my unit, so I suspect the previous owner swapped one out. To be safe, I ordered two of each spec (as well as fuses while I was at it just in case). I'm using the replacement for the one that seemed like it hadn't been removed before (GBPC1502), but that's just a hunch.
https://www.mouser.com/ProductDetail/512-GBPC1502
The other (AP MB352) seems to be discontinued, so I ordered its replacement.
https://www.mouser.com/ProductDetail/583-MP352
The difference seems to be the average rectified forward current. I have the 15A installed, but I also have 35A in case that's a better option. This is out of my wheelhouse, so I'd appreciate advice. I understand the concept of a bridge rectifier, but I'm not sure which current rating is a good match.
Thanks for the help. The silence is golden!
I just swapped out the bridge rectifiers tonight, and the buzz is essentially gone. Hardly audible if I put my ear right next to the transformer.
Incidentally, there were two different rectifiers in my unit, so I suspect the previous owner swapped one out. To be safe, I ordered two of each spec (as well as fuses while I was at it just in case). I'm using the replacement for the one that seemed like it hadn't been removed before (GBPC1502), but that's just a hunch.
https://www.mouser.com/ProductDetail/512-GBPC1502
The other (AP MB352) seems to be discontinued, so I ordered its replacement.
https://www.mouser.com/ProductDetail/583-MP352
The difference seems to be the average rectified forward current. I have the 15A installed, but I also have 35A in case that's a better option. This is out of my wheelhouse, so I'd appreciate advice. I understand the concept of a bridge rectifier, but I'm not sure which current rating is a good match.
Thanks for the help. The silence is golden!
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- Scodiddly
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Re: ghost power supply buzz?
Told ya.
Current rating is basically just buying whatever has a high enough current rating to pass the amount of current you'll need, worst case. Obviously higher current rating devices are bigger, more expensive, etc. so generally you buy just a little bigger than what you'll need.
Current rating is basically just buying whatever has a high enough current rating to pass the amount of current you'll need, worst case. Obviously higher current rating devices are bigger, more expensive, etc. so generally you buy just a little bigger than what you'll need.
Re: ghost power supply buzz?
Great to know. Thanks again!
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