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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Transformer vibrating. How to eliminate it posted by Rick on April 9, 2000 at 17:59:12:
My Parasound and diy amp with four x-formers, have a hum problem. Very annoying!
Finally I decided to take care of it. This is what I did:
1. Took out x-formers, removed original tape and insulation around x-former, (they're thoroids).
2. Dipped them in polyuerathane (<--don't know spelling) lacquer. Let them dry three days, did it twice. This was an attempt to pot the windings. Unfortunately the inner insulation was not removed, so couldn't pot the inner (primary) coil, since that required removal of secondary coil.
3. Epoxied the x-former, inside and out, black epoxy for better dissipation.
4. Epoxied rubber mount in the center of each x-former.
5. Mounted x-formers on seperate 4mm aluminum plates, the x-formers fastened firmly but floating in the rubber mount. The alu plates were then mounted in chassis with three non-symmetrically placed rubber mounts.I think that was about it. The first few days was great, total lack of noise! I was so happy. The day one of my buds came over to hear the silence, a slight hum was present!!! Now, after about six months, there is a slight hum. It is vastly improved, but still there, tho only noticable when not playing music and being quiet.
I do have a total of five large x-formers tho, and must expect some noise from them. Yes, they are good quality types.I guess the conclusion is that some hum is usually present no matter what, tho not always, the quality of x-former and how it's mounted surely is an important factor.
If u don't want to take the above steps, simply rubber mounting them in the chassis helps some.
Some square type x-formers may also be tweaked, simple screw off the covers and take it from there.
Just make sure that heat must be able to dissipate. Since much money is saved by using small x-formers, some amps have x-formers operating near their power limit and will be hot.
BTW. Don't overtight a thoroid! Unless the mounting bolt is epoxied to it. If it's mounted with loose covers overtightning will 'crunch' the coils, perhaps shorting them.
Oh, another thing: Some electric supplies are not 100% symmetrical, and I've heard folks say there's a slight difference when flipping the plug in the wall! Won't work with US type plugs that aren't symmetric of course, but if u live in a country with symmetric plugs...
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Follow Ups
- Re: Transformer vibrating. How to eliminate it - hans 05:02:16 04/10/00 (1)
- Thanks A lot, Hans. I will try to do it. (nt) - Rick 18:03:09 04/10/00 (0)
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