Electro Harmonix POG bypass problem

[beatnik]

Hello,

I have a problem with an Electro Harmonix POG first version

The status light works and bypass signal is ok

Footswitch is not doing anything. Pedal is permanently in bypass

I’ve checked the footswitch contacts and they are actually fine.

I don't understand if either the relay is defective or the microprocessor is not sending signal to the relay

Can you help me understand how to troubleshoot the switching part ?

Schematic is attached

[Jazz P Bass]

Look at the base leg of Q1 to see if it goes hi/ low when the switch is depressed.

[beatnik]

Q1 base voltage is constantly at 0V. Could be the transistor itself or maybe the microprocessor is dead ?

[Jazz P Bass]

If you look at the schematic, Q1's base leg should be connected to the 3.3Vdc rail.

Find out why the base is low.

[beatnik]

actually r23 and r32 are not installed on the board

it seems q1 gets control voltage from the dsp_sw point

i have permanent 0V on the dsp_sw test point and i guess that's where the problem is ?

[Jazz P Bass]

I can't follow that schematic.

What is the footswitch input to toggle on the bypass? (bypass sys?)

You need to look at that point to see if the controller is getting the proper input.

[beatnik]

bypass_sys is getting the right voltage on input - switching between 0V and 3.3V

i think the problem is in the output ?