Ok. Official Easy Vibe Debugging request

[bifbangpow]

All right. well. I tried to modify the john hollis easy vibe to have a 3pdt footswitch and both mattery snap and power input jack.  I seem to be having some real trouble. so here goes the whole shebang.

Problem: NO clean sound. No fx. Weird pulsing noise when hooked to Amp. Also LED 6 lights up automatically....

Original project:  http://www.geofex.com/PCB_layouts/Layouts/easyvibe.pdf

Wiring diagram for modification I came up with... (hope it's correct):



And my opamp ic chips read as follows:

U1:   (1) .03
        (2)  1.5
        (3)  1.07
        (4)  0
        (5)  1.38
        (6)  1.38
        (7)  STARTS AT 5.0 AND GOES UP INFINITELY
        (  8.9

U2:   (1)  4.6 AND GOES UP
        (2)  4.6 AND GOES UP
        (3)  4.9 AND UP
        (4)  .03
        (5)  4.8
        (6)  4.7
        (7)  4.7
        (  8.9

U3:   (1)  O
        (2)  4.7
        (3)  4.7
        (4)  .11
        (5)  1.08
        (6)  4.26
        (7)  4.4
        (  8.9

U4:  (1)  4.5
       (2)  3.0
       (3)  4.5
       (4)  .02
       (5)  4.7
       (6)  4.7
       (7)  4.7
       (  8.9

If I had to guess i would think the readings for the first chip are not good... but I'm still trying to learn the troubleshooting process. Please help! 

[thermionix]

(Sorry, not helpful, but your artwork reminded me of this)

[bifbangpow]

(Sorry, not helpful, but your artwork reminded me of this)

haha. oh god. mine is definitely not artwork hahahaha

[Ben Lyman]

This is the schematic, maybe it will help someone spot something with the voltage readings you posted
http://www.hollis.co.uk/john/easyvibe.jpg

[bifbangpow]

Yes I'm in real dyre straights here.  I'm kinda surprised no one has been able to help me yet. Usually these threads go fast!

[Kipper4]

Unfortunately the schematic is not numbered

So I'm guessing which is which
In the input buffer and subsequent phase stages pins 1 2 3 5 6 7 (if it's a dual package)
Should be around Half of V+   (4v5)
Pins four at gnd
Pin Eight at V+

That is unless it's the lfo.

And my opamp ic chips read as follows:

U1:   (1) .03  it's looks like the whole thing is off. Biasing should be 4v5
        (2)  1.5 ?
        (3)  1.07 ?
        (4)  0
        (5)  1.38  ?
        (6)  1.38. ?
        (7)  STARTS AT 5.0 AND GOES UP INFINITELY     how far? Just kidding. Not good.....
        (  8.9

U2:   (1)  4.6 AND GOES UP.   This might be the lfo
        (2)  4.6 AND GOES UP
        (3)  4.9 AND UP
        (4)  .03
        (5)  4.8
        (6)  4.7
        (7)  4.7
        (  8.9

U3:   (1)  O     very suspect
        (2)  4.7
        (3)  4.7
        (4)  .11
        (5)  1.08 suspect ? Might be meter loading.
        (6)  4.26
        (7)  4.4
        (  8.9

U4:  (1)  4.5
       (2)  3.0
       (3)  4.5
       (4)  .02
       (5)  4.7
       (6)  4.7
       (7)  4.7
       (  8.9

If I had to guess i would think the readings for the first chip are not good... but I'm still trying to learn the troubleshooting process. Please help!
[/quote]

[bifbangpow]

That is unless it's the lfo.

And my opamp ic chips read as follows:

U1:   (1) .03  it's looks like the whole thing is off. Biasing should be 4v5
        (2)  1.5 ?
        (3)  1.07 ?
        (4)  0
        (5)  1.38  ?
        (6)  1.38. ?
        (7)  STARTS AT 5.0 AND GOES UP INFINITELY     how far? Just kidding. Not good.....
        (  8.9

U2:   (1)  4.6 AND GOES UP.   This might be the lfo
        (2)  4.6 AND GOES UP
        (3)  4.9 AND UP
        (4)  .03
        (5)  4.8
        (6)  4.7
        (7)  4.7
        (  8.9

U3:   (1)  O     very suspect
        (2)  4.7
        (3)  4.7
        (4)  .11
        (5)  1.08 suspect ? Might be meter loading.
        (6)  4.26
        (7)  4.4
        (  8.9

Thanks for checking those for me.  So I'm looking at bad op-amps or a short before the ist opamp?

[bifbangpow]

What would cause my op amps voltage readings to be so wrong?

[thermionix]

The offboard wiring seems correct in the drawing you posted, so probably something not right on the board.  Can you post pictures front and back of your PCB?

[bifbangpow]

The offboard wiring seems correct in the drawing you posted, so probably something not right on the board.  Can you post pictures front and back of your PCB?

Sure.

Back of the board:




Front of the board:

[thermionix]

Excellent, clear photos.  Right off the bat I see that most, if not all, of your electrolytic caps are installed backwards.  The + lead goes in the square pad.

There may be more...

[thermionix]

Yeah I think even C7 needs to be reversed, but I'm not 100% sure on that one.

There's no indication on the Geofex layout of the orientation of LED1-4.  My first thought is that it probably doesn't matter because they are being fed a sine wave.  But you'd want them all the same way, right?  Sorry, I don't know the circuit, so I'm a bit confused there.

[bifbangpow]

Excellent, clear photos.  Right off the bat I see that most, if not all, of your electrolytic caps are installed backwards.  The + lead goes in the square pad.

There may be more...

Did I seriously do that?  WTF. What a stupid rookie mistake.  haha

[bifbangpow]

...
There's no indication on the Geofex layout of the orientation of LED1-4.  My first thought is that it probably doesn't matter because they are being fed a sine wave.  But you'd want them all the same way, right?  Sorry, I don't know the circuit, so I'm a bit confused there....

Yeah I assumed if there was no markings then it didnt matter.    But if anyone knows which direction they go that would be great. 

I rotated them so that they are all positive on the left side and negative on the right. 
Still nothing.  stay tuned.

[thermionix]

Excellent, clear photos.  Right off the bat I see that most, if not all, of your electrolytic caps are installed backwards.  The + lead goes in the square pad.

There may be more...

Did I seriously do that?  WTF. What a stupid rookie mistake.  haha

Ah, nobody is born with it, we learn as we go.  Some of the electrolytics may be fine swapped around.  Some may have been damaged by reverse voltage.  Only way I know to be sure is to replace them all.

When Duck gets here (6:30AM Pacific time) he will probably spot some things I missed.

I'd like it if someone more knowlegable than me can comment on those 4 LEDS.  Should they all be the same way in the circuit?  Two one way, two the other?

[thermionix]

I'd like it if someone more knowlegable than me can comment on those 4 LEDS.  Should they all be the same way in the circuit?  Two one way, two the other?

Oh duh, I see the schematic that Ben posted.  Has them all going the same direction.  Don't know why there isn't a square pad on the Geofex PCB layout.  Still maybe they can be reversed as long as they all are...?

Also seems John Hollis specified heat shrink over the LED/LDR combos.  Maybe not such a big deal in a sealed up enclosure, but probably better to do it.

[Ben Lyman]

heat shrink over the LED/LDR combos.  Maybe not such a big deal in a sealed up enclosure, but probably better to do it.

Definitely do it because as soon as one LED lights up inside that enclosure, all the LDR's are going to think it's the 4th of July.
Also, it's a good idea to tilt all those LDR's so they are facing dead on to the top of each LED because that is where the LED shines the brightest.

[Cozybuilder]

Further on the homebrew vactrols; these will work better if the LED is pointing directly at the LDR, not obliquely. You could sand a flat on the end of the LED and superglue it to the LDR, then cover with heat shrink. For added light protection you could seal the lead ends also (I do that with non-corrosive black RTV; Permatex Item #81158).

[duck_arse]

R.G. is the sort of smart cookie that would layout a board with all the leds oriented one way. looking at your leds, I can see the anvils of some, indicating the kathodes. second from left is obscured, but second from right is backwards to the outer two, which appear correct. [tayda users beware!]



I'd face the ldr's flat to the led-ends, but wouldn't be so worried about light leak once boxed. the leds will be swamping the ldr's cause they are so close, and they all go off together. but yeah, tube them.

how did you manage the trimpot connection, did you extenderise the wiper lead?

[bifbangpow]

I'd face the ldr's flat to the led-ends, but wouldn't be so worried about light leak once boxed. the leds will be swamping the ldr's cause they are so close, and they all go off together. but yeah, tube them.

how did you manage the trimpot connection, did you extenderise the wiper lead?

You're all very helpful.  Yes last night I remembered the leadframe method of identifying negative lead and switched all the reversed leds.  But I think I need to replace all the electrolytic caps now.

As for heatshrinking the leds and vactrols... I'm going to assume the entire vactrol and led head should be sealed inside the shrink?

p.s. extenderise?  I'm not familiar.  I simply soldered the wires into the lugs on the pots.