Can someone explain this connection

[proaudioguy]

The bias is connected to the oscilator circuit. Just trying to understand what is happening here and why.

[sluckey]

The bias is connected to the oscilator circuit. Just trying to understand what is happening here and why.

The bias holds the oscillator and driver tubes in cutoff whenever the footswitch is missing or the contacts are not connected. When you ground that point by stepping on the footswitch the sudden change from big negative voltage to zero volts on the grids shocks the oscillator into quick operation (ie, fast startup). This circuit is found in all the AB763 amps as well as many other Fender amps. This is also the reason you must have a footswitch connected (or some other grounding method such as an RCA shorting plug) in order for the tremolo to work.

[Ten Over]

The bias is connected to the oscilator circuit. Just trying to understand what is happening here and why.

Sometimes the neon lamp in the LDR unit will remain lit when the LFO stops unless you put the LDR driver tube into cut-off. If the neon lamp remains lit, the Intensity control acts like a volume control of sorts. The negative bias voltage stops the LFO and extinguishes the neon lamp.