I have a BV300HB and the schematic and some know how...I went to set the bias on a new set of 6550's. The specs say set to -120mV to ground on tp #1.
It's a negative bias setup so reducing the voltage to say -110mV would make it run hotter...I had the new tubes in it for a couple of months with no problems but i thought hey...maybe I can make it sound better by heating it up a bit. So I broke out the DVM and went to set the bias and it reads -88mV! should have exploded way back. The tubes do not glow/get hot after several hours on. Why would it be out of range like this? Any ideas or things to try?