Tech question for Brownface Fender? Help!

[Goldstrat]

I picked up this Brownface Fender and there is a pot that is adjustable on it h dfoh way. It connects to the Presence knob, the cahssis ground and to a small circuit board near the transformer. Can someone tell me if this is for Biasing or maybe a midrange adjustment? I don't want to turn it in case it is for Biasing. Thank for any help!


http://www.johnstafford.net/JJ/gut/P1020268.jpg

[Blue Strat]

Yes, it does appear to be a bias pot. It only seems to be associated with the presence pot because part of each circuit shares the same ground connection.

[Goldstrat]

Thank you! Can anyone point me to some instructions on how to use it?

[Blue Strat]

Best/safest way to use it is to get a bias probe like Bias King, Bias Rite, etc.

Google will turn these up.