Jim Mueller wrote:





For those of you who work on a lot of this tube equipment, does it seem
that 140V B+ is low? It does to me, with 450V AC coming from the power
transformer,

Probably bad electrolytics, at least for the first guess. If this had
been a receiver, there would be a loud hum.


** Please read the thread.

1. There is a baby size transformer that put out 250-0-250 with no load.

2. The AC voltage peaks are clipped under load so the peak value is about 270V.

3. There is a 6X5 rectifier that drops 50V off as well.

4. Then there is a 5000 ohms resistor before the filter electro that causes another a large voltage drop.

A voltage of 140V on the electro about right, the trick of being that it allows just one 16uF part to do the job.


...... Phil