Vox VT20+ footswitch issues

[Deva]

So I've recently bought a VOX VFS5 pedal and it is working on other amp, the problem is that on this Vox VT20+ amp the LED lights up but there is no response on the amp even tho I can select the channels manually I can't select them with the pedal(The pedal was tested and it works). I noticed that even when I select a channel, the preset selector works witch is not supposed to be working. I think that then there is a short of some sort somewhere but I can't seem to find it :/. Can you guys help out? I can't even find the schematic for this amp witch makes everything worse. Thanks to everyone that gives me a reply! Cheers from Croatia!

[dmeek]

This is the footswitch input for the VT20+ modes are selected with different voltages on the ring, tip is +5v. The selected voltage goes to IC3 pin 56.
There are many schematics for VFS5 clone pedals. I'm not sure how close they are to the Vox original,

[Deva]

This is the footswitch input for the VT20+ modes are selected with different voltages on the ring, tip is +5v. The selected voltage goes to IC3 pin 56.
There are many schematics for VFS5 clone pedals. I'm not sure how close they are to the Vox original,

I measured across the ressistor and the IC3, the voltage changes as I change the Banks and that is no good bcs the current changes am I right? Do you have any Idea what could that be?

[Jazz P Bass]

"I measured across the resistor and the IC3, the voltage changes as I change the Banks and that is no good bcs the current changes am I right? Do you have any Idea what could that be?"

This is a very confusing statement.

[Deva]

"I measured across the resistor and the IC3, the voltage changes as I change the Banks and that is no good bcs the current changes am I right? Do you have any Idea what could that be?"

This is a very confusing statement.

So I plugged in my pedal and tried changing the banks(The stored presets on an amp) with the pedal and there is voltage change in the circuit, but It does not work still

[Deva]

Can you tell me what parts to check? So the problem is my pedal is getting power but not interacting with the amps Channels.

[Jazz P Bass]

If you are getting 'different' input voltages at the input pin of IC3 & it does not act correctly, then most probably IC 3 is bad.

[Deva]

If you are getting 'different' input voltages at the input pin of IC3 & it does not act correctly, then most probably IC 3 is bad.

Tested all switches for channels on the IC3 and they work, there is constant voltage on the FOOTSW pin 2.3V and still is not changing channels

[dmeek]

Check the voltage at the footswitch jack ring terminal to see if the voltage changes when you switch channels with the footswitch. If it does , then check at CN3-1, then CN4-1, then R279 both sides.
You could have a broken jack, bad connection to the main board, an open L1 ferrite bead or an open R279.

[Deva]

Check the voltage at the footswitch jack ring terminal to see if the voltage changes when you switch channels with the footswitch. If it does , then check at CN3-1, then CN4-1, then R279 both sides.
You could have a broken jack, bad connection to the main board, an open L1 ferrite bead or an open R279.

Gonna Check it right now, I'll send what happend in the evening, Cheers!

[Deva]

Check the voltage at the footswitch jack ring terminal to see if the voltage changes when you switch channels with the footswitch. If it does , then check at CN3-1, then CN4-1, then R279 both sides.
You could have a broken jack, bad connection to the main board, an open L1 ferrite bead or an open R279.

update, the voltage changes on the connector when switching banks, but when switching channels it is the same

[dmeek]

Check with an ohmeter that the ground of the footswitch plug is connected to the ground of the amp

[Deva]

Check with an ohmeter that the ground of the footswitch plug is connected to the ground of the amp

Yes the ground from the connector grounded on the board, I put a probe on a connector ground and on C216 and It beeps
And the pedal Lights up and changes colors as you press the bank button but it does not do it on the amp