WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
BTW, your board and the ST-70 are still in hibernation, shame on me. This thread will certainly bring back the desire of the project to the 2012 resolution, LOL.