BOSS CH-1 JFET Switching Issue

[noach]

Hello all.
I recently obtained a BOSS CH-1 that doesn't pass the wet signal, even when 'switched on'. The LED turns on/off, but the signal stays dry. I did some testing, and it seems that the issue lies with JFET Q2. When switching, the resistance between drain and source remains negligible, and the voltage at the gate stays constant. I am not sure where to go from here.

I also tested out Q4, and everything seems to work fine on that switch.

Here is the schematic:
https://www.synthxl.com/wp-content/uploads/2020/03/Boss-CH-1-T-Service-Manual.pdf

Thanks for reading!

[PRR]

Welcome!

> the voltage at the gate stays constant. I am not sure where to go from here.

That points to Q5 not doing its thing. It can be hard to find fault in the high-Z gate network so I'd just inspect solder joints then replace D4 C20 R24 R28.

[noach]

Thank you! I'll try this out.

[noach]

It's quite interesting, I poked around a bit more, and realized that the voltage on the collector of Q5 is actually varying with the switch. It only seems to be staying constant at the joint between C20, D4, and R24. What could be causing this?

[antonis]

the voltage on the collector of Q5 is actually varying with the switch.

Could you be more specific, plz..??

[noach]

Referenced to ground, when the effect is 'active' (LED on), the voltage at the collector of Q5 is around 4.3 volts. When I flip the switch to the 'off' state, the voltage decreases to ~4.1 volts. This is different than the junction between diode D4, C20, and R24, where the voltage is staying constant.