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Crest CA6 buzzing transformer.

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Lucasdude View Drop Down
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    Posted: 09 February 2022 at 8:28pm
I recently bought 4 CA6s and a CA4 ex install and in a pretty sorry state. I checked that they all powered up and came out of protection before handing over the folding, but that's as much as I could do. I have dismantled all of them and cleaned everything, and they all power up fine but one has a fairly loud buzzing transformer. Would anyone know if this may cause a problem in the near future?


Edited by Lucasdude - 10 February 2022 at 12:54am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jbl_man Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2022 at 8:01am
Sounds like one of the windings is loose and vibrating? The old cure use to be dunk it in a pot of varnish overnight,and let dry for a week, other than that if it's really annoying,needs a replacement?
Be seeing you.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2022 at 8:57am
Unusual for a toroidal transformer to buzz much as they have a low radiated magnetic field by design. Check the fixing bolts are tight (I think the crest has one top and one bottom into a tapped nylon boss?). I assume the rest of the amp is working perfectly? A partially open circuit rectifier could theoretically cause a buzzing noise in the transformer, it was something I was taught but have never experienced it.
Worth checking the idle current consumption compared to a silent one in case the buzzing is the amp working hard at doing nothing.
Kevin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Lucasdude Quote  Post ReplyReply Direct Link To This Post Posted: 10 February 2022 at 3:02pm
Thanks for the feedback. I've checked both the bolts and they are both tight. Sadly, I lack both the skills and test equipment to delve any further into the issue. Kev-a bit of a long shot, but would you know if the transformers between CA and Pro series are interchangeable? I've see a couple of old Renkus P2500s for sale as scrap. Any good to me?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote kedwardsleisure Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2022 at 3:40pm
sorry I have no idea but the CA range have been upgraded over the years and even 2 that look the same on the outside may not have the same innards exactly.
Kevin

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 11 February 2022 at 4:18pm
Is it definitely a toroidal? I've never seen one of those "buzz", but plenty of the older laminated units dry out & the varnish/glue deteriorates and they buzz like crazy..

Or a short somewhere could be drawing excessive current & make the tranformer groan a bit. Try isolate the thing, ie unplug from the amp modules and then the bridge rectifier and see if the problem persists. Or maybe it's a leaky cap. An odd one.




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