Neovibe help

[pete74]

Hello.   Made up a ggg univibe a few days ago.   Light pulses as it should, but I'm not hearing any effect (always a dry sounding signal).   Checked voltages at points indicated in the pdf and they seem pretty close to correct for all.  I've left the lightshield off just for the pic below, when it's on I don't hear any difference.



I've built a dozen or so pedals before but never really had many issues to troubleshoot, so I'm pretty new there.   Any suggestions as to where I should begin here?

Schematics are at: http://www.generalguitargadgets.com/effects-projects/modulationecho/univibe/

[EBK]

Maybe tilt those LDRs up so they are directly facing the light.

[pete74]

Maybe tilt those LDRs up so they are directly facing the light.

I would try that but sadly,  I've already snipped off the leads.   Can I somehow verify that is the issue before ordering 4 more?

[EBK]

You can probably solder new leads to those if you want to, but I understand why you'd want to test things a bit more first.  Perhaps a small mirror or shiny foil over top will reflect enough light to make something audible.  Worth a shot.

[pete74]

You can probably solder new leads to those if you want to, but I understand why you'd want to test things a bit more first.  Perhaps a small mirror or shiny foil over top will reflect enough light to make something audible.  Worth a shot.

My lightshield has tinfoil on the inside and makes no audible difference when it's on...

[EBK]

Maybe try a bright flashlight in a dark room to see if you can make it do something?

[pete74]

Maybe try a bright flashlight in a dark room to see if you can make it do something?

Just tried a flashlight, makes no difference.  Seem to have lots of light from the bulb tho.
 

[EBK]

Maybe try a bright flashlight in a dark room to see if you can make it do something?

Just tried, makes no difference.

OK.  You'll need to have those LDRs tip up 90° eventually anyway, but I'd say check voltages next.  One of the schematics on the linked page had some values to compare to.

[GiovannyS10]

Can you post the solderside, please? (double sided, right?)

You have to see a thing: You really solded the LDRs wrong... But i think it is not your problem. Have you replaced any transistor for another one? Double check if its pinout are correct Have you no sound when the fx is activated or a weird sound?

[Jaicen_solo]

If the light is working, the Lfo section is all working, so ignore all the parts in the bottom half of the board, assuming your 15v regulator is ok.

If you halear nothing, get an audio probe on it and follow the signal path through from the first transistor. My guess is you have a wiring issue.

[pete74]

If the light is working, the Lfo section is all working, so ignore all the parts in the bottom half of the board, assuming your 15v regulator is ok.

If you halear nothing, get an audio probe on it and follow the signal path through from the first transistor. My guess is you have a wiring issue.

Got it with a probe...   apparently I was colorblind when wiring my switch.       
Thanks everyone.

[Jaicen_solo]

Excellent work. Also do yourself a favour and be sure to use a large enought supply to give you 20-24v after the rectifier.  It will work at less, but the depth of modulation will be less.

[pete74]

I've added a 3pdt w/LED connected to pad O (as seen in another post http://www.diystompboxes.com/smfforum/index.php?topic=83206.msg695898#msg695898)....    Anyone know why when I engage the effect (stomp on 'da switch) there is now a delay where there is no sound at all for a second or so and then everything kind of fades in?

[thermionix]

Is the effect powered off when in bypass?

[pete74]

Is the effect powered off when in bypass?

Nope... lamp is still pulsing

[pete74]

I've added a 3pdt w/LED connected to pad O (as seen in another post http://www.diystompboxes.com/smfforum/index.php?topic=83206.msg695898#msg695898)....    Anyone know why when I engage the effect (stomp on 'da switch) there is now a delay where there is no sound at all for a second or so and then everything kind of fades in?

As it turns out, pad O on my PCB is actually a ground...