1) Every now and then, monitor the Balance settings by flicking the BAL switch to the left side:
2) Then compare with readings with the BAL on the right side :
What the meter reads doesn’t matter at all, but you must make sure that both BAL readings are the same in 1) and 2).
To do so, adjust the BAL preset with a flat screwdriver as you repeat step 1) and 2).
keep adjusting it until readings are the same on 1) and 2).
You will notice that when you turn the preset in one direction to increase the meter reading in 1) it will decrease the reading in 2) at the same time, so just keep flicking from one side to the other adjusting the preset in the right direction until you achieve the same reading on the BAL positions.
Once you have finished adjusting them, flick the switch back to ZERO for normal gain reduction reading and do the other channel.
IMPORTANT :
All tubes in a FAIRCHILD should be well matched, it is very important.
I would always expect the BAL preset setting to be between 9 O’clock and 3 O’clock maximum.
Do not run your FAIRCHILD with any of the BAL presets almost all the way up or down on one side, something is obviously wrong, and the matching of your tubes has become very poor.
Please contact me first, I can either re-measure all your tubes for free and suggest a new arrangement for them all, or tell you if any tubes have gone very low or bad, or noisy, or I can simply help you move your tubes around so that you have a better quad arrangement on both sides.
Remember : Bad Balancing and high biasing can cause output transformer failure, especially when combined with very high operating levels and low output loads.