On Sat, 05 Mar 2016 09:11:39 -0500, Boris Mohar
wrote:

On Sat, 5 Mar 2016 05:01:45 -0800 (PST), " wrote:

On Friday, March 4, 2016 at 10:24:44 PM UTC-5, Phil Allison wrote:
wrote:

I don't buy your story of the 1N4004 diode being reversed, 6550s draw
over 500mA each with positive grid bias and the amp would have quickly
blown up if that were the case.


... Phil

Well, when I put the diode in correctly (per the schematic), the hum
reduced greatly and the amp draws about 30 watt less than before. When
new caps arrive, I will try them out. Could also be that the diode was
bad in the first place, not sure as this is the first time I checked it.

Peter Wieck
Melrose Park, PA


It could be that the original diode was Selenium which has much larger Vf.

This is clearly the case in images of this model and later schematics
also show a 2W 6K8 shunt resistor across the first filter cap.

RL