Boss RV-3 Problem-No Dry Output

[RedRabbit]

Hey Folks, I've been lurking here for years and finally have a problem that I can't solve through research or brute force.
Hopefully someone here has experienced this first hand.

I recently received a semi-working Boss RV3 Reverb/Delay as a throw in for a project guitar I was selling. The guy told me there was something wrong with the mix pot, and I instantly figured that it was dirty or a lead had broken or whatnot. Turns out there is no dry signal output at all. When the knob is turned fully left there is no output, when there should be just dry signal. The effected signal works and sounds good, but there is no dry mixed with it.

I've checked for continuity across all of the dry path, as well as checking for component shorts there as well. All the pots have been cleaned to hell and back.

I'm curious if anyone has experienced this first hand with this pedal or any Boss pedal and how they resolved it. Hopefully someone has an answer before I have to spend a good day in there with an audio probe. I'm admittedly pretty awful at SMT work since I have super sausage hands and none of the correct tools, but I have some talented friends who could pull it off.

Thanks!

http://www.freeinfosociety.com/electronics/schematics/audio/pictures/bossRV3.jpg

[PRR]

Signal tracer. Find where dry signal stops.

[slacker]

Do you get a signal in bypass and if you use the right output does it do the same thing?

[RedRabbit]

Do you get a signal in bypass and if you use the right output does it do the same thing?

There is signal in bypass. Output A&B both do the same thing.

[slacker]

Ok then, so we know the bypass/dry signal is making it from the input, through IC2 through Q4 and then through IC1 to the output. When you turn the effect on Q4 opens stopping the dry signal passing through it and Q2 is supposed to close allowing the dry signal to pass that way instead where it gets mixed with the wet signal from Q8 and Q7.
I would start audio probing round Q2 and see where the dry signal stops. If you have a meter measure the voltages on the collectors of Q6 and Q5 when the pedal is bypassed and on, you should get the opposite voltages so if one's 9 volts the other should be near zero. Q5 switches Q2 so the problem could be round there. 

[RedRabbit]

Thanks a bunch for your help slacker.

Since I need to dig around and find my audio probe (or build a new one), I took a meter to Q6 and Q5. The collectors are opposite voltages when bypassed/on at 7v just like you said.

Now, I took a meter to Q2....

When the effect is bypassed, D-3.65v, S-3.65v, G-0.0v
When the effect is on, D-3.65v, S-3.65v, G- 0.01V

Speaking of Q2, what transistor is that? I can't read the pixellated text in the schematic. I know it's an N-JFET, but every permutation of what I think it is, isn't it. 

[RedRabbit]

Speaking of Q2, what transistor is that? I can't read the pixellated text in the schematic. I know it's an N-JFET, but every permutation of what I think it is, isn't it. 

Just found the service manual. Q2 is 2SK880GR. I still haven't determined if it's the faulty component, but both mouser and digikey don't have it in stock. Any suggestions?

[PRR]

Any N-type JFET will work well enough to prove that's the problem.

[RedRabbit]

Fixed! Faulty Q2...
98 cent N-JFET from RatShack works just fine.

Thanks for the help guys!