Antonio Vernucci wrote:
I've only been up against the wall twice, and I unwound the burned windings,
and counted the turns. (write the numbers down, and don't lose the paper)-
--------- (don't ask me how I know)

Thanks for the tip, but in our case the transformer had already been re-wound
once. Unfortunately voltages are incorrect, so it must be re-wound for the
second time. And it is therefore not possible to determine the number of turns
for the various windings.

How incorrect ARE the voltages?

If the plate voltage is 20% high for instance, measuring the DC level,
that means the AC voltage on that winding is 20% high too. And so you
need to remove 20% of the windings. So you do have a reference after all.

In the solid state world you can just assume the DC voltage after the
rectifier is 1.414 times the AC voltage, minus the diode drop. Problem
is that in the tube world there is often a substantial resistive loss
through the vacuum diode.

But, you can measure that! Measure the DC drop across the diode, then
work from the desired DC voltage, plus the drop, times 1.414 to get
the AC you need. (This is assuming the diode drop will change only a
little bit once you get the voltage perfect. If it's not, use the
nomograph in the RCA HB-3 handbook to work it out).
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."