Power Transformer is vibrating loudly

[in a vacuum]

This is not an electronic buzz, but a physical buzz. All the circuits work fine. Roland solid state amplifier has a loud--hear it all the way across a room--buzz caused by a vibration of the power transformer. I have removed the power transformer and can wiggle the core a bit, so I assume that it is vibrating against the laminations. What is a safe and effective way to deal with this looseness and stop the vibration?
Thanks in advance.

[Jazz P Bass]

I would Google 'Transformer Construction'.
I am under the impression that transformers are dipped in laquer & baked.

[Steve Conner]

Pedantic maybe, but the "core" is the iron slab composed of the stack of "laminations". The part in the middle that carries the windings, and from your description the part that has come loose, is the "bobbin".

Maybe you can jam some sort of wedge between it and the core. A plectrum, a piece of credit card or something.

[J M Fahey]

You can put it on a table, over some newspaper or cardboard to minimize the mess, incline the transformer 45š to work easier and drip, say, half a teaspoon of paint (*not* water based, but "oil" synthetic paint/lacquer/wood varnish/car paint/etc.) between the coil/bobbin an the core laminatioms.
It usually is enough.
Do it on both sides.

If you dare, tie the wires to a stick, so the heavy iron core and bobbin hang from it, and submerge it fully (leaving the wires and stick outside) into a can of paint or varnish as stated above although for full submersion avoid those with thinner, which may compromise wire insulation.
Leave it submerged for 1/2 hour, until you are *certain* the paint penetrated fully and it sheds no more bubbles.
Raise it out but fix the stick somehow (books/brcks/wood?) so excess paint drips back into the can, or into *something*.
Leave it alone at least overnight , so it drips no more and is dry enough to touch (although it probably will still be sticky).
Thansformer factories do the same, only they use a faster drying enamel, and often cook it in an oven to save time.
There are also air-dry ones (the ones I use).

[Chuck H]

You can put it on a table, over some newspaper or cardboard to minimize the mess, incline the transformer 45š to work easier and drip, say, half a teaspoon of paint (*not* water based, but "oil" synthetic paint/lacquer/wood varnish/car paint/etc.) between the coil/bobbin an the core laminatioms.

If you dare, tie the wires to a stick, so the heavy iron core and bobbin hang from it, and submerge it fully (leaving the wires and stick outside) into a can of paint or varnish as stated above although for full submersion avoid those with thinner, which may compromise wire insulation.

JM!?! I'm confused. Are the reasons to NOT use water based paint for the first procedure not of concearn for the second? I just don't know of any paint or varnish that doesn't use paint thinner AND doesn't use water.

The guys over at the pickup forum use mineral spirits (paint thinner) based varnish all day long without issues. I don't think mineral spirits will compromise the magnet wire or laminate coatings. Some thinners that may would be lacquer thinner, acetone and MEK. So I might avoid lacquer, but I've never tried it so I don't know for certain that it's a risk. But lacquer thinner is pretty hot stuff. Anything "fast dry" is going to have a hot solvent in it. Avoid those.

One other tip. The longer you let it dry after dipping, the less it will stink when the transformer is used. And it will stink. At least a little. And for a long time.

I don't know what the actual magnetics shops use for potting but it's kind of like a rosin that is really sticky for awhile and slowly hardens. But continues to harden and seems to get quite brittle when very old.

[J M Fahey]

JM!?! I'm confused. Are the reasons to NOT use water based paint for the first procedure not of concearn for the second? I just don't know of any paint or varnish that doesn't use paint thinner AND doesn't use water.

The guys over at the pickup forum use mineral spirits (paint thinner) based varnish all day long without issues. I don't think mineral spirits will compromise the magnet wire or laminate coatings. Some thinners that may would be lacquer thinner, acetone and MEK. So I might avoid lacquer, but I've never tried it so I don't know for certain that it's a risk. But lacquer thinner is pretty hot stuff. Anything "fast dry" is going to have a hot solvent in it. Avoid those.

One other tip. The longer you let it dry after dipping, the less it will stink when the transformer is used. And it will stink. At least a little. And for a long time.

I don't know what the actual magnetics shops use for potting but it's kind of like a rosin that is really sticky for awhile and slowly hardens. But continues to harden and seems to get quite brittle when very old.

Hi chuck h , letīs go step by step.
Maybe the confusion comes because because the US (maybe English) definition of "pain thinner" is quite loose (ours is tighter).
In a very loose term, *everything* that makes a paint thinner is "paint thinner" ... and that would include *water* !!! , because thatīs exactly what it does to water based paints !!! so letīs tune these definitions a little.
a) what *we* call plain "thinner" (and obviously itīs not "our" word but US or British origin) is what you call "lacquer thinner".
Itīs a complex mixture , meant for quick drying, and solvent for paints which harden by plain evaporation and nothing else.
Typical "car" paints (as well as classic guitar paints) : Nitrocellulose (yellowish) in the old times, acrylic (transparent) paint today.
This paint can be dripped between core and bobbin but its strong solvents are dangerous to some insulations so no no for submersion.
These solvents are mainly Ethyl Ether and Acetone, plus a myriad others to control drying time, enhance brightness even without polishing, behave better on humid days, etc.
Iīve seen some formulas , they may have up to 18 ingredients. (additives, cathalyzers, etc.)
May include some heavy alcohols , even Butyl Glycol (Butylic Alcohol?)
2) then there are those "safe" multi purpose paints, which in the old times were based on "oil" (some modified cousin of linseed oil) and disolved with natural (tree) turpentine and in modern times based on some synthetic "oil" and dissolved with a petroleum distillate *equivalent* to turpentine.
Itīs a petroleum fraction lighter than Kerosene but heavier than gasoline, maybe you can give me its name.
Google also calls it Turpentine or at best mineral turpentine while we use 2 very different names so confusion is impossible. (Which is good because they are chemically very different)
These "oil" paints harden in 2 phases, first by evaporation overnight and then by oxidation, which takes from a week to a month and *really* hardens it.
During this time it emits a strong pungent smell.
This paint (or the equivalent varnish) is safe to all wire enamels.
We call these: "Synthetic" paints . The "oil" part is implied.
3) water based paints should not be used in any case.
At least because of corrosion and besides, for safety reasons.
Sorry if I am still not clear, remember "things get lost in translation".
Commercial transformer varnish comes in 3 flavors.
The real old one was like the "synthetic" paints, took forever to dry.
The newer ones, dry only a little so as not to drip. and then are oven cured.
No oven: they never dry, keep soft and tacky forever.
The modern "air dry" ones are not like "nitro" paints, don't really know their formula, but the solvent smells close to Toluene and Xylene, the rubber contact cement solvents ... but the product is quite different.
As soon as it dries a little (maybe in 1/2 hour), it turns to a gel which later can never be re-dissolved even if applying more solvent.
Sorry for writing so much, but paints are fascinating ... an there are thousands different ones which we have never even mentioned.

[Chuck H]

Sorry for writing so much, but paints are fascinating ... an there are thousands different ones which we have never even mentioned.

LOL... Thank you for the paint chemistry lesson. I'm actually a painting contractor by day job. I also served many years on a paint store counter solving problems for uneducated contractors. As well as having been a tinter. Paint chemistry as it applies to usage doesn't confuse me typically. I just wanted to be sure the OP had info they could take to any hardware store (God knows the guy behind that counter doesn't know squat) and get what he needs.

Love you man.

[J M Fahey]

OK, thanks.
Yes, the main problem is getting the store clerks selling you what you need, for which *the customer* needs a clear notion first.
Anyway I think the OP will be able to use any old non water based paint can he has sleeping in his garage shelves.
Itīs unlikely he has some "car type" paint ... unless he actually paints cars.
He needs the kind of paint that once opened develops a "skin" on its surface and is usuallybthinned by what you call "mineral turpentine".
Itīs usually the cheapest, most common (non water based ) paint.
Maybe you can suggest some brands, not for him buying exactly those but to have a clearer idea (as in the store clerk saying; "I donīt have *that* one, but I can sell you ....")
Good luck.

[pdf64]

'Itīs a petroleum fraction lighter than Kerosene but heavier than gasoline, maybe you can give me its name.'
I think it may be white spirit.
I alawys wondered what the difference was between it and turps; they are sold for equivilant thinning / brush cleaning purposes in the UK.
White spirit - Wikipedia, the free encyclopedia

[Prairie Dawg]

How about polyurethane varnish like the stuff Minwax sells?

[Chuck H]

That would be fine too. Varnish is the typical go to product for ameture potting. It dries painfully slow and has more of a tendancy to stay wet in pockets where it pools and skins. But the same properties that make it do that also make it more flexible for a long time. Eventually becoming brittle with great age. Polyurethane would get harder sooner with a shorter cure time. Not sure what the long term performance difference would be except to say that it seems to get brittle with extreme age on woodwork in less time than varnish.

[Chuck H]

'Itīs a petroleum fraction lighter than Kerosene but heavier than gasoline, maybe you can give me its name.'
I think it may be white spirit.
I alawys wondered what the difference was between it and turps; they are sold for equivilant thinning / brush cleaning purposes in the UK.
White spirit - Wikipedia, the free encyclopedia

It's mineral spirits. Or paint thinner. You can buy it at any hardware store. Turp isn't used anymore in commercial finishes. Mostly because of expense. But also inconsistency and impurities can cause finishing problems with some modern coatings. Turp is a natural wood product (distilled from pine pitch usually) and white spirit (or mineral spirits) is a petroleum product.

[J M Fahey]

Bpth varnish suggestions would work great.
The "classic" ones.
Now it seems every classic paint is reborn "green", meaning water based . Not th same thing at all, plus we want no water, moisture, condensation, nothing watery inside.
In fact commercial transformers are dried in an oven for a couple hours before potting.
They also use vacuum chambers to do so, to pull out entrapped air quickly.
When you restore normal pressure, varnish rushes into the tiniest hidden spots.
But itīs too much for us.
Just dipping for, say, an hour is the maximum.
My brother in law yearly sands and re-varnishes all exposed wood in his sail yatch with excellent results with some kind of "Marine Varnish", which would be great for this.