Easyvibe questions

[scottso]

Hi folks!  New to the forums here and was hoping someone could help me out!

I etched a PC board for the Easyvibe and built it out last night.  The nutshell is that it doesn't seem to "vibe".  I get sound with the vib/chorus switch in both settings but it just seems clean with no phasing at all.  The bias LED's are lit solidly.  The first build I used some VTL5C2's I had lying around, but then I replaced them with an LDR/LED combo when I couldn't get it working and all the voltages seemed to match up with other people who had working ones (from searching the forum here).  But alas I still have the same issue. The LDR's I'm using drop down to about 2k in ambient room light and about 1.5M to 2M or so if I isolate them in an opaque box.

I'm also using NE5532's for all the opamps at the moment and 1n4148's for all the diodes. If I can't make progress I will post the entire diagnostics info as advised in the sticky, but I just wanted to be sure I'm not doing something dumb.

Schematic is here if needed: http://i149.photobucket.com/albums/s72/spudworks/Easyvibe_Schematic_Voltages.gif

My first question is, should the VTL5C2's work as an LDR/LED combo?  Datasheet is here: http://optoelectronics.perkinelmer.com/content/Datasheets/DTS_vtl5c1c2.pdf  It looked like it should work.

My second question is what is the orientation of the LED's for the LFO?  Its not marked on the schematics or board layouts I found and tracing the circuit it looked like the + side should be to the left.

And lastly even though I have the LED/LDR pair shrink tubed, I DO get a very very subtle phase sound just by moving my hand back and forth above the board. My scope shows the wave form changing too.  It looks like the LED's for the LFO are not lighting up, but the voltages seem fine, hence my first question.  What should the voltages be before and after the LED's?

Thanks in advance for any assistance.  This is my first really complicated build after making a few boosters and fuzz pedals and I'm a little overwhelmed at the complexity.  The easyvibe isn't so easy for me!

[petemoore]

  Good place to start, what I can offer.
  take an LED and put a current limiting resistor onit, the - mark on the side to battery - it should light.
  measure the voltage that goes to an LEd and see that the most - goes to the cathode.
  that voltage should move up and down [easiest to read with the rate all or most of the way down]. If it doesn't then the LFO driving the LEd's isn't functioning properly.

[Andre]

There are 2 versions of the PCB.
If the text on the one you did says: "CORP 2001 R G KEEN", please check if the one pin of R18 which is closest to the LED does not short with the trace right next to it.
R.G. did a small change to the PCB design in 2006 to avoid this short.
The text on this one is: "CORP 2001-2006 R G KEEN.

André

[d95err]

First of all, try to find out if the LFO is running at all. Put an LED in paralell with the LED/LDR combo's and check that it is pulsating properly.

[GibsonGM]

...or tap into that spot and see if you can see the waveform on your scope....

[scottso]

Thanks so much for all the input!  It helped me track down my dumbness.  I had one of the LED's backwards!! Doh.     It never ceases to amaze me how one little simple thing can cause so much time spent tracking it down.

My lesson is never trust that the long lead is ALWAYS positive.  Test the darn things every single time.

[oldrocker]

Thanks so much for all the input!  It helped me track down my dumbness.  I had one of the LED's backwards!! Doh.     It never ceases to amaze me how one little simple thing can cause so much time spent tracking it down.

My lesson is never trust that the long lead is ALWAYS positive.  Test the darn things every single time.

YES!  Always double check.  I even double check resistor values.  I take nothing for granted.