***THERE IS HIGH VOLTAGE ON THE TUBE BOARD. BE CAREFUL WHEN ADJUSTING THE SMALL POT ON THE BOARD.***
***THIS ADJUSTMENT IS DONE WITH THE UNIT ON.***
1) Unplug the unit and take the cover off by unscrewing all the phillips screws on the top. Then remove the two top allen screws on the front panel, one above the input knob and one above the time constant knob. Remove top.
2) With a flat head screwdriver twist the front panel balance pot both directions to get a feel for where the center of the turn is. If it had a knob on it (it doesn’t) and numbers from 1 to 10, you would want to the knob to sit at 5. Leave it in the middle.
3) Remove the 8 tubes by slightly rotating them while pulling up. Put them aside.
4) The new matched set of tubes will be numbered 1-8 in they’re boxes. Put them in according to the diagram below.
6) After warm up, the LED on the front panel will most likely be red or green. Use a small eye glass screwdriver to adjust the small pot on the tube board circled in the picture above. This is where you should be careful not to drop the screwdriver onto the tube board around the tubes since there is 200V on the board. Keep turning it till the LED turns off. If you keep turning it further the LED will turn the opposite color. You don’t want it to be red or green but right between the two colors and off. It may take many turns to turn the led off. If it wont turn off after 10 or so rotations, turn it the other way.
7) Turn the unit off and unplug it. Replace the top, all the phillips screws, and the two allen screws on the front. Your done.