Neo Vibe Troubleshooting

[parser]

Hello,
I powered up my implementation for a NeoVibe at http://www.geofex.com/Article_Folders/univibe/vibeupdate.pdf  and surprisingly, at first attempt, I had the lamp pulsing and working properly. The problem is in the sound that appears to be UNPROCESSED at all.. do you have any advice where I should put my attention on ?     

[Kevin Mitchell]

Hey, welcome to the forum.
With the info provided it sounds like an issue with your bypass switch wiring. But we can't confirm that since more detailed photos have not been provided.

[parser]

Hi Kevin, thanks for helping me. I'm not using a DPDT by now (since I'm testing the unit) so, the effect is always in the "EFFECT ON" path. The ground was not properly connected to the L pad. Now it is, but the effect still doesn't process the signal. Moreover, if I set the volume at top, I just hear noise. I added another picture...

[antonis]

Hi & Welcome.. 

Have you performed testing with photocell covered..??

[Kevin Mitchell]

Oh, okay. Smart move! And thanks for the full picture.

If you have no guitar signal at all on the output then you likely have a short, cold solder, bad trace or bad part somewhere along the signal path (more likely a short). You should make an audio probe, follow the schematic and see where the signal drops out.

In case you didn't know, without the cap on the LDR/Lamp setup your room's light will keep the LDRs stuck on low resistance so you won't really hear the phasing. But that wouldn't cause the guitar signal to disappear.

Do you hear any artifacts from the LFO pulsing? If not then perhaps the error is further down the circuit near the output stage.

Good luck!

[parser]

 
.. and actually it was a short after soldering! I have now a deep phasing effect. BTW, yesterday I fried a transistor (Q12) trying to read voltages..
Thanks a lot again 

[Kevin Mitchell]

Awesome, great job!
Onto the next!

[parser]

..
Onto the next!

Yep, it will be a Distortion Device whose project is taken from a 1978 magazine. It has 6 BC109C NPN transistors, 3 knobs and 5 switches. 

[antonis]

Awesome, great job!
Onto the next!

2 fried transistors, at least..??

[Kevin Mitchell]

Awesome, great job!
Onto the next!

2 fried transistors, at least..??

Sometimes you've got to blow up a few parts to learn and move forward!
When a new member comes along and more-or-less troubleshoots their build themselves, it's indeed a great job. Especially on a home-etched board like this one.

[parser]

Awesome, great job!
Onto the next!

2 fried transistors, at least..??

Sometimes you've got to blow up a few parts to learn and move forward!
When a new member comes along and more-or-less troubleshoots their build themselves, it's indeed a great job. Especially on a home-etched board like this one.

BTW, my board was an "artwork" all etched by myself with a dremel tool (yes man, it can be done ) 

[parser]

2 fried transistors, at least..??
[/quote]

Exactly one (Q12), to be precise

[Kevin Mitchell]

My goodness, man! Well... that's one way to do it.
I've never wished to unsee something as much as this. Ok I'm over exaggerating, but it works and that's quite impressive! So box it and never show it again

Hit the bottom of the board with some clearcoat to prevent oxidation.
And please try an chemical etching next time lol. You'll save yourself a ton of work.