Testing functionality of output transformer-Is it DOA?

[Cygnus_X1]

On testing the output transformer...since I don't have a filament transformer I connected a portable radio to the
OT primary.
From the headphone jack.
Connected speaker to the correct jack.

It pushes the signal, although it is weak.
I guess that tells me the OT is good?
Or does this not mean anything at all?

I must emphasize that the amp was unplugged and discharged when doing this, the OT was connected and the tubes out of the amp.

[eleventeen]

IMO that (what you described) tells you nothing particularly useful. I'm sure I don't have to tell you that it tells you nothing wrt high voltage integrity. Dead, out of the circuit, there isn't a heck of a lot you can test apart from the equal resistance of the matched halves of the primary if it is push-pull, whether the secondary is intact end-to-end and among its taps, and whether there is any short or very low resistance between the primary, the core = the frame, and any of the secondary taps. There *could* be an internal strapping of the "0" ohm output lead to ground, but that's not desirable nor common. If you're using an older VTVM to test continuity watch out for zaps coming through the primary when you break the connection(s) after testing.

[PRR]

> equal resistance of the matched halves of the primary if it is push-pull

DC resistance between primary halves is not critical. You want as low as possible, but don't want excess weight or cost. So it may be 10% or 5% of the nominal audio impedance, and in simple guitar amps the outer half is always 20%-50% higher resistance than the inner half.

The -audio- impedance matches because the turns are equal (invariably more equal than a P-P amp needs to be). The _resistance_ differs because same turns around the outside of the coil buildup is a longer length of winding. But since resistance is much smaller than audio impedance, we just don't care (or not enough to pay for complicated winding techniques which don't sound any different).

> it is weak.

Yes. The voltage is stepped-down about 30 times. It should sound like a 120V lamp being fed 4V: really really dim. You proved it is not a dead short, but there's several ways this could "work" yet be a lousy power amp OT.

What makes you think the OT is bad?

Why don't you have a heater transformer? Don't you have ANY tube amps?

[Cygnus_X1]

Well, I didn't have any PT's handy at the moment and didn't want to untie anything just yet..

I have too many amps!
Thank you for the tips-I'm lazy sometimes.

Turned out the amp had a freaky cathode resistor plugging all of the signal.
It works now.