Transformer hum after warmup

Dynaco-Doctor Forum

Welcome! Need support, you got it. Or share your ideas and experiences.

I have an ST-70 with the Curcio mods and it has developed a mechanical hum in the transformer. I assume it is the power transformer.
On startup, the amp sounds great but after 10 minutes or so I hear a crackle through the rt speaker and then the transformer begins to hum fairly loudly. Should I get a new power transformer? What tests should I run?
I built this thing about 20 years ago and have forgotten most of what I know about it. Thanks for any assistance!
Joe

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Topic - Transformer hum after warmup - jclark1@utk.edu 06:31:45 02/18/25 (0)

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