Kevin at Dynakitparts recently relayed the following story to me ..
"Bob, Attached photo of a failed P-782 power transformer brought to me for evaluation. A recent Ebay purchase by a customer of mine looking to save a few dollars on his MK III amplifier project. This transformer caught on fire immediately upon powering up.
Seller claimed this was removed from a good working amplifier although there were no return provisions listed in the Ad. I feel bad for this customer and many others who have gone this route in pursuit a good deal.
Dynaco products for the most part were well made and a great value. Their power transformers were not designed to last 50 years. In addition, today's higher line voltages will place an additional burden on these vintage power transformers resulting in higher secondary voltages and increased temperature rise.
The photo reveals the extent of failure to this unit. Take note of the burned windings and leads. This is a good example and reason not to install a used transformer of "unknown" origin on your next amplifier project.
Regards, Kevin @ Dynakit"
Understand that many Dynaco transformers are more than 50 years old and buying a used POWER (especially) transformer can sometimes be a "roll of the dice". If you are going to play a Dynaco amp on a daily basis buy a NEW power transformer.