1965 VOX AC50 MkIII questions

[ericlc]

Hi all,

I have a VOX AC50 (serial 3317) on the bench.
It is functional but weak and noisy.
Most caps are end of life and resistors are out of spec.
It is a version without the infamous brimistor.

I have a question about the output transformer.
It has a loose wire which seems to have broken off from a ground point.
The bare wire goes through the chassis near the speaker output terminals.
It was isolated with band aid........internally the lead is connected to the secondaries.

I could safely isolate this wire again, but does anyone know how this is supposed to be terminated?

Best,
Eric

[sluckey]

Most likely connects together with the black wire at the speaker terminal block.

[ericlc]

Thanks.
Yes, it does connect to the other secondary leads.
I probably need do some measurements to see how it is connected internally

[pdf64]

That OT looks unusual, perhaps a replacement, and seems to have been tinkered with.

[ericlc]

Indeed. This seems to be a 6K transformer rather than 3k5

[Roe]

the right OT is crucial here.

https://pacificaudiomagnetics.com/produ ... ransformer
https://www.facebook.com/photo/?fbid=83 ... 9313359373

[Roe]

I had two ac50s at my bench at the same time. I tried to swap the OT on one, doing an a/b test. the stock OT sound very warm with excellent bass.

[ericlc]

Thanks.
Modulus is UK based which is convenient since I am in The Netherlands.

[ericlc]

Indeed the OT was doctored with.
It turned out not being original either as the chassis cutout was altered as well along with additional mounting holes.
I did replace it with a replacement OT from Modulus as suggested (thanks Roe).
It is again a wonderful amp now with lots of low end.