Foot switch education please

[trem]

I do not have a foot switch for this amp. I thought the trem would work with just a dummy plug in the Tremolo Jack, but it does not. Obviously, I am reading the schematic incorrectly.
Can somebody explain to me what happens with the foot switch that makes the trem funtion.? The trem fs is in the middle, lower portion of the schem.....
Thank You

http://www.0rigami.com/vb/traynor_mkiii_ygl3_3a_b.pdf

[g1]

This amp does not require a footswitch to turn the tremolo on. The switch in the trem. footswitch jack is normally closed when no footswitch is connected. The footswitch (or dummy plug) is only needed to turn the trem. off. It could be the switch in the jack is dirty, defective, or there is something else wrong in the trem. circuit.

[trem]

I cannot tell if the Trem is On or Off when no plug is inserted. I wish I could figure that out for starters.
I have tried a dummy plug, and a plug with the tip shorted to the sleeve. Neither of those plugs will turn on the Trem. So, I guess there must be something else wrong.....
Thanks

[52 Bill]

The circuit appears to be a copy of the typical Fender blackface oscillator, where the grid of V3B is held negative by a negative bias voltage until the footswitch grounds out the bias voltage.

The footswitch jack shows a normally closed contact, so no footswitch is needed to make the trem work, unless the jack contact is dirty.

Check V3 as well as the three phase shift loop caps and related resistors.

[trem]

The circuit appears to be a copy of the typical Fender blackface oscillator, where the grid of V3B is held negative by a negative bias voltage until the footswitch grounds out the bias voltage.

The footswitch jack shows a normally closed contact, so no footswitch is needed to make the trem work, unless the jack contact is dirty.

Check V3 as well as the three phase shift loop caps and related resistors.

It does seem I have more going on that a switch issue. As soon as a get a chance, I will check the Trem tube and components in that circuit.
Are you saying that when the ground is lifted, the grid of V3 goes so far Negative that it does not draw any current.? Is that how it shuts the Trem tube "on and off".?
Thank You

[52 Bill]

Are you saying that when the ground is lifted, the grid of V3 goes so far Negative that it does not draw any current.? Is that how it shuts the Trem tube "on and off".?
Thank You

Yes, if you look at the schematic the negative output section bias supply voltage is fed through a 3M3 resistor to the footswitch jack's hot contact. The negative voltage is then carried to the grid of V3B via the 2M2 resistor.

When the jack connection is open (un-grounded) the negative voltage will appear at the grid shutting off the oscillator. When the jack is grounded two things happen. One, the negative voltage is grounded out so the grid can turn on the tube and two, the speed control leg of the circuit is grounded, reducing the value of that leg enough that the phase shift circuit will be able to oscillate.

[Jazz P Bass]

Thankyou 52 Bill for elucidating the function of the footswitch jack.