How long do output transformers last?

[joeriz]

Just wondering as I am in the process of rebuilding one of my ST-70s. Short of user abuse, how long can one expect output transformers to last? Does simple use/age eventually render them unusable? I've seen folks write about things like core deterioration with age.

Or, with proper care, can one expect them to last pretty much indefinitely?

(My particular set is approaching 50 years old!)

Thanks,
Joe

[dcriner]

They should last indefinitely. The only thing that might go wrong is that a winding will open up, but it's either good or bad.

You could tighten the through-bolts to compress the core laminations.
Doug

[hilldweller]

They should last indefinitely. The only thing that might go wrong is that a winding will open up, but it's either good or bad.

You could tighten the through-bolts to compress the core laminations.
Doug

If you tighten the bolts to compress the laminations, Would this possibly create a gap between the winding and the lam core and than cause hum??? Sounds Risky To Me. Yellow_Light_Colorz_PDT_14

[erichayes]

Actually, tightening the screws will lessen the buzz some older transformers develop, and marginally increase their efficiency. Good transformer manufacturers now use a combination vacuum-hot varnish procedure to keep the laminations from flapping around and making noise.

[hilldweller]

Thanks Eric, I always learn something new when I visit the forum. I appreciate the opportunity to learn from knowledgeable people. A real blessing! :) :) :)

[Shannon Parks]

Not exactly the same thing, but just saw this this morning:
http://therealbobroberts.net/iso.html