Stage fright

[Jules]

Hi all, I will start by saying what a great community this is and the help I have recieved has been fantastic so thanks a lot everyone.
I have built a stage fright phaser and I cannot get it to work for me.
When I turn the trimpot manually whilst a chord is ringing out the phaser works but only while I turn the trimpot.
The LED flashes in time with the speed knob as it should.
Does anyone have any ideas about what I have done wrong here?
Thanks again
Jules

[TGP39]

Jules,
     Are you getting no sound when you aren't turning the trimpot? Or just no phaser effect?

     Try reflowing the solder where that trimpot is.  You may have a bad solder joint there. It's an easy attempt at fixing this issue. If it doesn't work, we can look deeper into the circuit.

Steve.

[Jules]

Steve, when I turn the trimpot it gives me the phase effect as I turn it.
I am getting sound when not turning the pot, just no phase effect. Thanks for your suggestion will try that

[Jules]

reflowed a few solder joints and now working perfectly.

[TGP39]

reflowed a few solder joints and now working perfectly.

Awesome!  Enjoy....

Steve

[ravendark]

I am having this exact same problem. I also tried reflowing the solder on the trim pot with no luck. What else should I look for to try and fix this issue?

[TGP39]

Hi Tony. Your phasing only works when you are turning the trimpot also?
Do you get the guitar sound, but no phasing?

Steve.

[ravendark]

That's correct. I get the signal without phasing. when I turn the trimpot, it effects the signal, but I don't actually get the phasing with the lfo.

[TGP39]

Ok. This is a little different. Do you have a Digital Multimeter?  Are you able to take voltage readings on all your IC's?  Also, sometimes a picture is really worth a thousand words. This info would go a long way in narrowing down the problem.

Steve.

[ravendark]

I do have a DMM. Here are the voltages

on all LM13700
Pins 1 and 16- 1.2V
Pins 3 and 14- 4.2V

TL074
Pins 5, 7 and 8- 4.2V
pin 10- 3.5V

Tl062
Pins 3 and 5- 4.2V
pin2- 3.8V

Here are a couple pics
http://i357.photobucket.com/albums/oo13/whamola_man/sf%20front_zpszw5vvxcd.jpg
http://i357.photobucket.com/albums/oo13/whamola_man/sf%20back_zpsvhhqeiax.jpg

thanks for the help!

 

[TGP39]

I can't really see it, but make sure q1,q2 and q3 are the correct transistors and oriented properly on the board.

Steve.

[ravendark]

The transistors were in correctly. I reflowed all of the solder joints on the board and the pedal came to life.
Thanks for your help!!

[TGP39]

So glad Tony!  I'm going to have to build this one myself. Have fun.

Steve.