Unexpected increased distortion (=earlier breakup) in vntage Silvertone 1482 tube amp

[Helmholtz]

I asked about an oscilloscope.
This would allow to verify output power.

[g1]

Carlo, what is the line voltage at your location? Is the amp set up for 240V operation? Or are you using an external step-down transformer?

[slidincharlie (Carlo P)]

Carlo, what is the line voltage at your location? Is the amp set up for 240V operation? Or are you using an external step-down transformer?

The line voltage is around 230 VAC. I had the power tranny rebuilt by a tech a few years ago. I provided him with the specs shown in the schematic. Honestly I don't remember if I asked him for 220 (which was the common value back then) or 230 V operation.
The point is that the amp started to have a more distorted sound recently, after a long period of normal operation (given that this is a crunchy, wild little amp of its own anyway).

[g1]

I wasn't thinking about the distortion, just the lower value voltages you were finding.

[Helmholtz]

I wasn't thinking about the distortion, just the lower value voltages you were finding.

But the problem showed up only recently?

[g1]

But the problem showed up only recently?

Yes. But I don't think we need to be concerned about the lowish voltages unless the line voltage is not getting to the PT primary. Unless the voltages were checked and found to match schematic when PT was replaced.
Carlo, can you verify full line voltage is getting to primary of PT ?

[slidincharlie (Carlo P)]

Yes. But I don't think we need to be concerned about the lowish voltages unless the line voltage is not getting to the PT primary. Unless the voltages were checked and found to match schematic when PT was replaced.
Carlo, can you verify full line voltage is getting to primary of PT ?

How would I do that?
I read full line voltage (223 V right now, but it can get as high as 230 V at times) on the fuse holder, which is the first tie point of the AC supply from the wall socket.

[g1]

One probe to the fuse holder, the other probe to the power switch. Try both sides of fuse to both sides of switch. Should all give the same reading as what is coming out of the wall.
This is assuming it is still wired up as schematic shows, with switch on one side of AC and fuse on the other.

[Helmholtz]

I'm not concerned with voltages being low by less than 20%.
If something prevents the full mains voltage from getting to the PT primary, this something should get quite hot.
But let's see...

[slidincharlie (Carlo P)]

One probe to the fuse holder, the other probe to the power switch. Try both sides of fuse to both sides of switch. Should all give the same reading as what is coming out of the wall.
This is assuming it is still wired up as schematic shows, with switch on one side of AC and fuse on the other.

Yes, the amp is wired up as the schematic shows. And yes, probing the fuse holder against the switch in each of the four possible combinations always gives the same VAC reading.