determine VA of unlabeled transformers

[matt20102]

Greetings, all

I've got several transformers from old dismantled audio components- a 1/4" RTR and sony receiver, to be exact. Is there any way to measure/determine the VA ratings of these transformers other than google searches (not helpful), equipment power ratings or the physical size of the unit itself?

One or more of these transformers is destined to become a part of a GC project with the LM3886. The transformers themselves are fairly large; the RTR transformer about 3lb, maybe ~3in^3; the sony (from a 120W amp with 4 simult. speaker outs) about 5lb, ~4in^3.

Thanks...

[BlackDog]

The equipment they came out of normally states a mains power rating on the back of the chassis....? Should be accurate enough.

[pinkmouse]

I was chatting about this with a guy who fixes old studio kit a week or so ago, and his rule of thumb is 1 kilo per 100VA.

[I_Forgot]

used to have info about transformer size vs. power. Hams were always doing things on the cheap, including rewinding power transformers to get the voltages and currents needed. There is a direct correlation between the core size and the power input/output of a transformer. I'll see if I can find my old copy and post the info later.

I_F