no effect on Hummingbird Layout

[Charan]

Hello, I'm new to this forum and also new to vero. After my first successful vero experience (a silicon Tonebender), I moved on to build the Earthquaker Hummingbird, which is a dream pedal for me. I've gotten all the parts together and tried out the circuit w/breadboard, battery, and, jacks. In all of my tests, I get a (fairly) clean tone out of the circuit with no effects. The level pot works, but the other pots and mode switch do nothing. Pics are below.




 

I realize that there are many posts about unreliability of the silicon UJT transistor, and a generous soul is sending me a tested UJT. But in the meantime, it bothers me that even if I remove the UJT the sound is unchanged. Does anyone who has built this have troubleshooting suggestions?

p.s. I've posted a little on this on the DIY stompboxes forum, and I've received very helpful responses about the transistor. I don't mean to waste time w/redundant posts, but I figure that this forum would be better for reaching people who have built this actual layout.
p.p.s. I can see in the photo that the 50k pot broke (my dog probably did it) but I did all my tests when the pot was intact.

[Charan]

Sorry a couple more bits to help:
-I kept spare rows at top bottom and right in case I would need to do any additions to the circuit.
-I used two resistors in series to approximate the 330k resistor in layout.

[Charan]

Hi, I just wanted to bump this. I've got a fresh UJT that was tested in two vox repeat percussion circuits, but it only puts out clean sound. Volume pot works, but depth and mode switches do nothing.

My guess is that the UJT is somehow disconnected from the audio path and that is why it is not modulating/regulating the output.

Does anyone know where I should check voltages or anything else I can check to trace the problem in the UJT subcircuit? Apparently, there is no sound in that part of the circuit, so I don't think audio probe will cut it (in fact, I probed it and there was only sound from the audio path, not in the UJT part of the circuit. I appreciate your help!

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[Beaker]

Hi there, I have built a few of these and all of them (sort of) worked first time, so there is no problem with the layout, However it is far from the most reliable of builds, and has sometimes defeated even experienced builders. Therefore I would not suggest this build to anyone without a half a dozen or so succesful builds under their belt first.

I suspect you have had no replies, as nobody wants to come across as a hard arse to a beginner. Build simple layouts first and get your skills honed - we have all tried to run before we can walk.

[Charan]

Thanks B, I get it. Actually, I think I fixed the problem--I replaced a transistor socket and re-did all the solder joints coming from the UJT base. Probably the issue was that I tried to hack by replacing a 330k w/270k+50k. This time I used a single 300k resistor. Anyway, so far, it looks like a happy ending and I can soon get in line behind the people who complain about the ticking :)

[Beaker]

Glad you got it sorted. There should have been no problem with wiring the two resistors in series, I am sure your problem was with your soldering. You need to make sure your solder joints are as good as you can possibly get them, so just take your time, work methodically and don't rush anything. Aim to get things as neat as possible on both sides of the board, and it will really help.

You will soon be posting up builds in the "show your pedal guts" thread.