Easy-Vibe Trouble

[Big Red]

1. John hollis easyvibe
2. http://geofex.com/PCB_layouts/Layouts/easyvibe.pdf
3. Followed layout exaclty. TL062 op-amps
4. No substitutions
5. Negative ground (I think)
6. When effect is engaged, an un-vibed sound comes out. Sometimes only on the chorus or vibe mode, the other is silent. After a while sound only comes out when the strings are hit hard and the sound is fuzzy.

The bias lights don't pulsate when depth pot is turned all the way up as described in Hollis' FAQ.

The effect did work until I put the back cover on the box, so I took the back cover off and lined the inside of the box and the bottom of the circuit board with construction paper. The effect doesn't work, even with the circuit board suspended in the air

IC1
1 = 3.82
2 = 3.81
3 = 1.79
4 = 0.001
5 = 3.78
6 = 3.80
7 = 3.80
8 = 8.19

IC2
1 = 3.80
2 = 3.81
3 = 3.80
4 = 0.001
5 = 3.78
6 = 8.18
7 = 0.921
8 = 8.18

IC3
1 = 3.80
2 = 3.80
3 = 3.79
4 = .001
5 = 3.80
6 = 3.77
7 = 6.68
8 = 8.17

IC4
1 = 3.80
2 = 3.80
3 = 3.82
4 = 0.001
5 = 3.78
6 = 3.80
7 = .760 - .834
8 = 8.16

diode = 0, 0.555
led2(top led of the 2 bias leds) = 3.80 volts
voltage is greater on the positive pins of all electrolytic caps
voltage of battery in engaged effect = 8.15 volts

sorry if I forgot anything. I typed this once allready, but it did that thing where you loose it all because you took to long to post. so I went through this one sort of quickly.

pictures of the board are on the way

[Big Red]

sorry, they are a little blurry

[petemoore]

IC3
1 = 3.80
2 = 3.80
3 = 3.79
*4 = .001  [see if the diode beep mode indicates this as connected to Gnd.
5 = 3.80
6 = 3.77
**7 = 6.68 this one should be near 1/2v...
8 = 8.17

IC4
1 = 3.80
2 = 3.80
3 = 3.82
*4 = 0.001 [should be Gnd = 0v, close...meter 'anomoly?' maybe?
5 = 3.78
6 = 3.80
**7 = .760 - .834, like IC 3 pin 7, should be closer to 1/2 v 
8 = 8.16
  All IC pins 4 are grounds or should be
  IC 3 and 4, their B opamp outputs [pins 7] seem to be mis-biased and too close to the +supply rail, look at the resistor values around these pins 7 on IC's 3 and 4.
  The rest of the input and output pins seem to be resting a little low, not sure how the EZ Vibes bias, should be close to 1/2v for optimal +/-  signal voltage swings, ...~within +/- 10%

[GibsonGM]

Maybe try going thru the power section (the v bias, 2 leds and all), be sure you're getting the right voltage.  Search the forum for EZ Vibe Debug, there is a jpg going around with some handy voltages...

[oldrocker]

Also make sure all the LED's are oriented correctly.  I know this may seem obvious but you'd be surprised how easy it is to get the polarity wrong when installing LED's.  I got mine right the first time with this build but to be honest until I fired it up I wasn't sure I had it right.  Just a suggestion.

[Big Red]

petemoore, I checked the resistors going into the #7 pins on ics 3 and 4, they are 10K resistors, giving readings of 8.8K and 9.0K ohms. and I assume that 0.001 is just the meter trying to be as precise as possible, so I take it to mean 0. my batteries are dead on my meter and I cant find the diode function on my dads which I'm using now, so I'll have to get abck to you.

GibsonGM, is this what you mean? http://i30.photobucket.com/albums/c345/stompbox_layouts/Easyvibe/Easyvibe_Debug.gif
I'm not gettingthe 0.35V on pin 3 of IC1, the 3.8V on pin 6 of IC2, 2.98V of pin 2 of IC2, and a few more.
everything seems to be getting 3.8 volts, as stated in john Hollis' FAQ http://www.hollis.co.uk/john/easyvibe.html

oldrocker, I'm sure the leds are orientated correctly because I was super careful installing them, and the effect was working for a while, but I will double check.

I'm not sure how to interpret the voltages that are incorrect. I went over all the joints and I completely re-did the offboard wiring. so now I'm at a loss

[petemoore]

  Just a thought...since it was working and something 'tripped' it into not working...and those OA's are 'funny' voltage wise, if you socketted the OA's maybe try swapping IC 3 'n 4 out ?
  By 'tripped' I mean something {Touched, then Removed in circuit = changed it to non functional. Quite often when 'something bad' causes a circuit to start not working, then is removed and the circuit still doesn't work, reasonable suspicion that the 'something bad' touched, and also made component[s bad.
  Since ^that [@ 9v] generally doesn't mess with resistors, the OA's and caps may become suspected, and if the LED"s don't light anymore, them too [I guess mainly those two in the PS Section...letsee...that leaves the board trace connections.. and ?...I think that's it for EZV components...
  DDMM-ing it [Dogmatic Digital Multimeter applications]...well...I've found troubles this way, testing for continuity across connections, non-continuity too where it's supposed to be NC'd to, resistor values...I just set the meter to beep and test anywhere I think a connection is made, the switch to R mode and start verifying values of resistors [mind that there are no alternate current path through the circuit or calculate/disregard the readings as such], when measuring each resistor. Maybe hook the DMM test clip to a rail, view schematic points to test/measure from there...mainly just applying the dern meter every which way imaginable...
  And substituting anything suspectable that doesn't lend itself to being tested or measured, to eliminate them as variables...a more part friendly way [instead of sticking fresh actives in a circuit which is acting up and causeing OA's to be suspect], take the suspect active out and put it in a socket with a circuit that Does work to test it. 

[Big Red]

  if the LED"s don't light anymore

sorry, I didnt word that very well, the 2 bias leds light up, they just dont pulsate.

I'll see if I have anything that runs on TL062. I'll try and pick up some new OA's

[stumper1]

It's been posted here somewhere before but,

If you etched a board from the link you posted there is an error in the PCB layout.  Not sure if this could cause your problems or not.

I don't have my notes here, but from the link posted:
Where LED4 connects to R19 (I thinks it says 19 - kinda fuzzy, it's the R between the drive pot and C9), looking at the picture - the lower pad of that R is connected to the trace from the bottom (-) side of C9. It should not be.

Hope this helps. Good luck

[Big Red]

Stumper1, is this what you mean? if so I corrected it allready http://i30.photobucket.com/albums/c345/stompbox_layouts/Easyvibe/EZvibe_Part.gif
thanks

[GibsonGM]

The Debug JPG is helpful, but I believe it's designed around 4 dual opamps...go with it if that's what you did ('62's right?).  Your voltages should be close altho not exact.  I built mine exactly like the Hollis layout, using '64's, so I had to 'infer' some voltages.

Check Stumper's advice, for sure, make sure that pad isn't connected!!  And then swapping out new op amps might be a good idea, too, in case one or both fried.  This might fix it.

The bias LED's don't oscillate...as long as they go on you're ok.  You say you have 3.8v between R23 and the 1st LED, so your bias is likely ok.  After checking that pad, you'd want to assure that the op amps are getting the ~9v at their power pins, and that ground is at 0.   THEN, starting at the first connection in the signal path, you have to follow the voltages until you find the glitch.   

Do your oscillator LED's strobe?  Nothing else will happen until they do.

[stumper1]

Stumper1, is this what you mean? if so I corrected it allready http://i30.photobucket.com/albums/c345/stompbox_layouts/Easyvibe/EZvibe_Part.gif
thanks

Yep.

Good luck!!