How to fix a buzzing transformer

[mikeydee77]

Magnetic lines travel through the shortest possible path, so at corners and top/bottom of center leg flux is minimal.

Not zero but so low as to become irrelevant.

That´s why factories punch holes *there*.

Nice diagram is worth a 1000 words... but in terms of remembering it much more so. Thanks Juan, another really useful bit of info.

[mikeydee77]

Had complete success with the transformer dunking in varnish.

Recipe I followed
Fitted some cable ties on transformer to help with dunking
Warmed transformer on radiator prior to dunking
Got an old fruit juice carton twice the height of the part
Lowered transformer into carton
Filled with polyurethane varnish diluted 20% with white spirit
Stirred around to encourage bubbles out
Left immersed for two hours
Raised out of varnish and drip dry, supported by chopstick to stop falling back into varnish
After a while poured varnish into tin for reuse.
Drip dry for 24h still bit sticky
Dried on warm radiator for further 24h

Result is transformer is absolutely silent. Really pleased with result.

Thanks to all for guidance hope this will help others...

[mozz]

For us on the other side of the pond, what is white spirit? Mineral spirit? Turpentine?

[Tom Phillips]

Had complete success with the transformer dunking in varnish....Result is transformer is absolutely silent. Really pleased with result...

That's great news. Thanks for reporting the results. It's always good to get a final report of a project like this.
Cheers,
Tom

[mikeydee77]

For us on the other side of the pond, what is white spirit? Mineral spirit? Turpentine?

According to google it it Mineral Spirit in the US.

Like a lot of English English terms it makes no sense. It is clear liquid, not white. Ha ha...

[Helmholtz]

https://en.wikipedia.org/wiki/White_spirit

White spirit (UK)[note 1] or mineral spirits (US, Canada), also known as mineral turpentine (AU/NZ), turpentine substitute, and petroleum spirits, is a petroleum-derived clear liquid used as a common organic solvent in painting.[1] There are also terms for specific kinds of mineral spirits, including Stoddard solvent and solvent naphtha (petroleum). Mineral spirits are often used as a paint thinner, or as a component thereof, though paint thinner is a broader category of solvent. Odorless mineral spirits (OMS) have been refined to remove the more toxic aromatic compounds, and are recommended for applications such as oil painting. ...

[Helmholtz]

Had complete success with the transformer dunking in varnish...
Thanks to all for guidance..

Might be worth a small donation to help the forum to survive?

[Pedro Vecino]

Reading it I also invited myself. Thanks!

[Mick Bailey]

For us on the other side of the pond, what is white spirit? Mineral spirit? Turpentine?

You've never heard the song 'Smells like white spirit'?

https://www.youtube.com/watch?v=QlCF04DVPK4

[mikeydee77]

Ha ha that was going through my head as well but thought it would not land internationally

[g1]

You've never heard the song 'Smells like white spirit'?

Once, on a painting job, was spinning out a brush with turps and a big gust of wind came and blew all the mist onto someones car parked nearby. There was still a fair bit of paint in the mist so I had to clean up the car before it had a chance to dry. Nowadays I probably would have set off their alarm and got myself in a pickle.