Old plexi Calsbro very low volume

[booba]

All right I did put with a variac 1.0v ac on the secondaries, 8 ohm tap.
I got 16.9 Vac plate-to-plate on the sockets.
If I do my maths correct, I have (16.9*16.9)*8 = 2284, a 2.3k primary. I should have 3.5k for 2xEL34 tubes.
So the OT is gone, right ? (still working, but low volume and no oooomph from power section) ?
Thanks ! :-)

Edit : did the same test on 16 ohm tap, 2.5k nearby

[Ted]

That certainly looks suspicious. Did you try the voltage between plates and CT? For an OT Failure that is often (but not always) significantly diffferent
between the two.

[booba]

That certainly looks suspicious. Did you try the voltage between plates and CT? For an OT Failure that is often (but not always) significantly diffferent
between the two.

You mean, an AC test with the 1Vac on the secondaries ? I only did pin3-to-pin3 AC.
Plates had the same 460v DC amp when amp was in operation.
Resistance on both sides from the CT was quite different (55 vs 79 ohm something like that)

[booba]

After more testing, I have 10Vac on one side and 7Vac on the other, from CT to plates.

[Ted]

Looks like thats your problem.

A 50W Marshall JMP transformer works fine.
I seem to remember it will even fit on the existing holes.

[booba]

A 2.5k primary + unbalanced sides means damaged coil so? That could lead to low volume?
Anyway i'm on for a new tranny. Thank you Ted !