Help diagnosing some issues with Uni-Vibe replica project

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gbkd80
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Post by gbkd80 »

So, I built myself a Uni-Vibe.
Image

I got an enclosure from Franco @ Argenziano Effetti, and originally was going to etch my own board but decided it was easier to get one pre-done from Brook at Pigeon FX. I used NOS 1/2w resistors (not sure brand, probably AB, had a ton of them), new Nichicon caps, some greenies from Tayda, BC108 in Q1 and 2SC945s for most of the remainder, but ran out and had to temporarily use some 828 pulls.

Originally I had some issues from wiring the transformer for 220v and I'm in the USA, so I corrected that. Then I had the PCB shorting against my standoffs accidentally (found this when the case halves were sparking :( but that's been resolved. I have a test footswitch mechanism built from a C100K dual-gang pot, 5-pin din socket and a switch similar to what is in the real pedal. I was having trouble getting the lamp to even pulse, and it was not bright at all. It turned out I had 2 bad transistors in the darlington pair, and that got the lamp going. Main issue is I am not getting any effect on output and barely getting any signal through from an instrument. So, I swapped out Q1 and still have an issue.

I'm more than likely going to swap out all of the transistors in the circuit with 2SC828s when they arrive but I'm wondering for the more experienced Vibe builders here (religiously went through the Sinner build thread and used most of the resources) if anyone has suggestions on where to look if I'm barely passing signal and no effect. I also noticed the transistor next to the trimpot can barely get a reading if the intensity is more than halfway dialed in. Flashing OL..

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