How to adjust the bias voltage and Replace power tubes

23-10-2013

*To replace power Vacuum tube in the left Signal channel,please set the control switch SELECT of the Liquid Crystal Display to the position of L. The Liquid Crystal Display shows the cathode voltage.   Adjust the Left BIAS potentiometer to make the display reen at 0.3v. Pull out the power tube after Turn off the power switch, and then select to insert the Vacuum tube to replace.Restart and adjust the bias potentiometer in the left adjust-L while looking at the display screen.The voltage shows as follows:
*The power tubes KT88 with bias voltage : 0.38V – 0.42V
*The power tubes KT66 with bias voltage : 0.35V – 0.38V
*The power tubes EL34 with bias voltage : 0.32V – 0.35V
*To replace power Vacuum tube in the right signal channel,please set the control switch select of the
Liquid Crystal Display to the position of R. The adjustment method is the same with L signal channel.
Please Remember to replace v7/v8 electron tube after Turn off the power switch.