2 Neovibe issues

[yeeshkul]

I finished a power supply and completely populated the Neovibe board. The supply works perfectly, the Neovibe has certain problems though:

1. LFO: it works, bulb blinks and the amplitude goes visibly up with the speed. I adjusted the trimpot (500 ohms) the way it was suggested here. But ... as i'm turning the intensity pot up the intensity reaches its maximum BUT then goes a bit down again (the very end of the pot turn).

2. Signal part: all these trannies - Q1,2,4,6,8,10 seem to be misbiased. Emitter voltages are either too close to base of higher. Is it possible that i burned them when i was testing it (i used different, highly suspicious power supply)?

thank you, i am soooo close now , Jan

[Arno van der Heijden]

2. Signal part: all these trannies - Q1,2,4,6,8,10 seem to be misbiased. Emitter voltages are either too close to base of higher. Is it possible that i burned them when i was testing it (i used different, highly suspicious power supply)?

Hi Jan,

I had the same problems with my build. It sounded fine, but the transistors you mention seemed to be misbiased.
Read about it in this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=56998.0

[axg20202]

+1.  IIR, many of my transistors appeared to be biased incorrectly from my readings, but I completed the build, hooked it up and the pedal sounds great. You could worry about this, but if it sounds right like mine did you can probably just go ahead and fagiddaboudit. Mine is still going strong.

Not sure about your pot problem though - have you tried replacing it?

[R.G.]

1. LFO: it works, bulb blinks and the amplitude goes visibly up with the speed. I adjusted the trimpot (500 ohms) the way it was suggested here. But ... as i'm turning the intensity pot up the intensity reaches its maximum BUT then goes a bit down again (the very end of the pot turn).

Probably loading on the output of the LFO. That LFO circuit is an oddity, and has many quirks.

2. Signal part: all these trannies - Q1,2,4,6,8,10 seem to be misbiased. Emitter voltages are either too close to base of higher. Is it possible that i burned them when i was testing it (i used different, highly suspicious power supply)?

Read the recommended thread. It may be the same quirk of measurement.

Here's a question: how does it sound? Have you listened to it?

[yeeshkul]

R.G. i just plugged it in and it sounds really good as far as i can judge. Clean, no distortion a bit weaker than the clean signal, but that is a known feature and i've already read your suggestions. It also "pumps" nicely. Trouble is that my AC15 broke down when i made Neovibe ready for the first fireup, so i had to test it just through computer. Another cursed project i have to laugh. But the result makes me really happy. I'll put together a build report soon.

Also thanks guys for encouraging me to plug it in despite the voltages, i was quite down ...