Debugging The Depths by EQD on Vero

[phamil90]

Link to build: https://tagboardeffects.blogspot.com/2016/11/earthquaker-devices-dephs.html

Link to Schematic: https://imgur.com/8R4keTO

So I've been working on this pedal (The first design with the offboard LED circuit) for a little bit and can't quite get it to work. I have signal passing through from input to output, but the signal isn't being effected by the LED pulses. The volume knob works, but nothing else seems to alter the sound.  The LED circuit seems to work fine (Yellow diffuse LED with GL5539s) since the LED rate and intensity changes with the pots, and I can hear a white noise pulsing with the LED using audio probing. I can't seem to find where the input signal gets lost through the effect circuit. I haven't made any modifications. Here are my voltages to ground:

IC1 (Top):
P1 = 4.4
P2 = 4.4
P3 = 3.9
P4 = 0
P5 = 4.2
P6 = 4.3
P7 = 3.3
P8 = 8.9

IC2 (Left):
P1 = 7.6
P2 = 6.0
P3 = 4.4
P4 = 0
P5 = 4.4
P6 = 4.7
P7 = 1.3
P8 = 8.9

IC3 (Right):
P1 = 1.5
P2 = 4.5
P3 = 4.4
P4 = 0
P5 = 4.4
P6 = 4.4
P7 = 7.5
P8 = 8.9

Q1 (Top): Varies with LED Intensity
C = 1.0 - 6.7
B = 0.7 - 3.1
E = 0.1 - 2.4

Q2 (Bottom):
C = varied too much to measure
B = 0.6
E = 0

D1 (LED): works fine

D2 (1n5817):
Anode = 9.2
Cathode = 8.9

Any help would be greatly appreciated! I'm considering just replacing the bottom two ICs and the MPSA18s, but was hoping y'all might have a more precise fix. Thanks!

[PRR]

Welcome.

When a thing don't work right, a Schematic is clearer than a layout. I happened to find the Schematic:
https://i.imgur.com/8R4keTO.png

However this is notated for the TL074 version, and you appear to have TL072, so all pin numbers change.

First odd thought is: you do have the LED/LDRs covered, dead-dark? Room light will overwhelm the LED blink.

[Fender3D]

Is it on breadboard yet?
Voltages on chips' pins should not be too far away from 1/2Vcc (pins 4 and 8 aside).
Check there

[duck_arse]

IC2 pin 7 and IC3 pin 1 both having the same badly wrong voltage, and both being on the same vero strip raises some questions about your trace cuts and solder shorts.

as someone says I always say, post some photos of what you have built.

and welcome.

[pinkjimiphoton]

i had this exact problem with my build. make sure your voice and intensity pots aren't wired backwards.

to this day i see confusion as to which pin is 1 or 3.

should fire right up. if its passing signal, and the led is flickering, check your soldering for a bridge. this circuit doesn't need to be in total dark, it will kick ass even in broad daylight.

when ya get it working, you can parallel the led with another for an external flashing indicator with no issues. just run two wires between the external led and the one on the board. it has to connect to the two points, if you ground it it will kill the led pulse.

pics would be useful. i DO have a schem for this with a couple separate oa's i think.  check FSB

[Harry Muff]

I made an account to chime in. the second one works, made two of them. I would do the 2nd one.

also, its kind of thin as in trebly or icy and is there any mod to help thicken it up some? im going to try the external blinking led mod thanks
jimiphoton

[phamil90]

Got it working!  It's a bit finicky when I mess around turning the pots way up or down.  It will stop pulsing for a bit but then start back up.  I ended up having to replace IC2.  I think there was a short underneath it.  Unfortunately, some of the vero strip came up with the IC and I ended up having to do some lateral jumpers to salvage the circuit.  Not the most elegant solution, but it works!

Thanks for the help y'all.

And Harry: I don't seem to have a very thin tone with my build.  What kind of LED and LDRs are you using?  You can really change the tone with different color LEDs and different LDRs.

[pinkjimiphoton]

I made an account to chime in. the second one works, made two of them. I would do the 2nd one.

also, its kind of thin as in trebly or icy and is there any mod to help thicken it up some? im going to try the external blinking led mod thanks
jimiphoton

should be completely transparent unless the depth and color knobs are pegged. this circuit is almost as good as the Black Cat, which is THE best vibe i've ever tried (and not cuz i work there).
i would check your signal path, cuz it should just be a buffer from in to out mostly. if its thin, check to see if you maybe used the wrong sized cap somewhere... hey, it happens!

[Harry Muff]

I cant seem to get the external led blinking. parallel means the same two holes right? my throb doesnt do anything either. I have an ultr violet with cheap ldrs. I guess have to place a small bear order soon for ldrs

how come a cm7371 lamp will not work in this? i have 5-6 of them in the junk box

[pinkjimiphoton]

the ultraviolet led is your problem, wrong light spectrum for the ldrs to respond to. you want green for this one, not that blueish purple.
they also draw different current i think and it may just be me, but i believe they radiate noise into the power supply as well.

yes, connect the two leds to the same spots remember  that if its on vero and ya tack it on the bottom of the board it may have to have its polarity reversed.

you could use a lamp, but it has a lot more current draw than what this circuit will allow i think. cold lamps are pretty high resistance, and it goes down as it heats up. you could try it. but it may blow something up.

[Harry Muff]

take the cathode to board and anode to a clr then to + rail for external lfo , seen the comments from gfx page and it works.  throb does nothing at all still. going to change out led now and place ldr order with small bear! small bear looks to have 4-5 types of ldrs you know which would you recommend? any fix on the throb control? i would like the bottom end swoosh over the harsh bite. mine is pretty much transparent but still has an icy edge to it on the high B and E that is a bit to shrill to use the fx imho. i need to work out a fix somehow.

im not good at this but looking at the schematic then the vero , is the 220nf and 22k network in the right spot?  looks like the 22k goes to neg inverter and the 220 to + out but backwards on vero as i cant follow the trade to the ldr like on the schematic. maybe a missing jumper there?

[pinkjimiphoton]

throb is fairly subtle it changes the "width" of the flash.

you don't need a current limiting resistor, just connect the led in parallel with the first one.

your problem is not the ldrs. your problem is the color led you're using. ultraviolet is about the worst color you can choose for this particular application. green is best, yellow or red will work, but blue or ultraviolet the cadmium or whatever in the ldr's won't react to.
changing the ldrs would be wasting your money.

just change the led.

[Harry Muff]

throb is fairly subtle it changes the "width" of the flash.

you don't need a current limiting resistor, just connect the led in parallel with the first one.

your problem is not the ldrs. your problem is the color led you're using. ultraviolet is about the worst color you can choose for this particular application. green is best, yellow or red will work, but blue or ultraviolet the cadmium or whatever in the ldr's won't react to.
changing the ldrs would be wasting your money.

just change the led.

will do! we need one of the resident experts to check that throb section of the scem and match it up to the vero , i cant follow it to tell but I suspecting something is off there maybe not though

[Harry Muff]

jimphoton its the diffused yellow  yessir my friend. now excuse me for the rest of the night while I go pretend to be jimi hendrix and gilmour in my jam room with my new play toy!

just seen you said green, will have to make a quick mod lol

the thin,icy shril is gone and with new LED the natural tone of my amp is coming through pretty darn good now

[pinkjimiphoton]

yeah boy!!!!! that is AWESOME. i @#$%ing LOVE mine.

i put it in a crybaby shell. it sounds better than my @#$%in univibe by far, real close to the black cat one that's my all time fav.

if it sounds good, box it and rock it, green and yellow i think should be more than close enough.

watch the throb control on the external led... you'll see it does change the way the light flashes at higher intensity and voice settings.
in some settings its actually useable, others barely noticeable. it controls the pulse width of the flash < i think >

psyched ya got it going... good on ya!! its a good feeling when ya first figure something out and fix it.

welcome to the forum.

[aishabag23]

I'd love to see a photo of that, Jimi! I bet it came out awesome.

[pinkjimiphoton]

hey aish,
seeing as how you made the board and popp'd it for me, here ya go!!

https://imgur.com/gallery/1zmXU











the big knobs are for the voice and intensity, the small ones are throb and volume.

works great, i call it the ashiewnivibe

[Harry Muff]

some reports back from the 4 hour jam, went through two stoner/doom compilations; 18 volt no good with my set up, yellow better than green, green didnt seem to work. the icy shrill on my high E and B appears with full distortion and with medium gain the pedal gets wet and transparent with the twang gone.

I replaced the 10k pot with a modern/vintage toggle to switch the 10k resistor in or out

Kept the clr on the paralelled led

[pinkjimiphoton]

clr on the external led willl mean its also on the primary led and will likely affect its performance adversely

the icy shrill at full distortion means you're clipping the input of the effect most likely.

sounds like something else is wrong with your build, bugger if i can figure it out

[Harry Muff]

clr on the external led willl mean its also on the primary led and will likely affect its performance adversely

the icy shrill at full distortion means you're clipping the input of the effect most likely.

sounds like something else is wrong with your build, bugger if i can figure it out

yeah there is definitely something wrong. if I take out the clr the lfo led quits working when voice goes above 40-50 %. it works, but I would not put it on my board and use it as is.  Its nothing like the 4000 video demos of just about every vibe on the tubes. could be my guitar set up and lousy guitar playing but I was hoping to at least get a similar tone to a Fulltn MDV or a MjM 60's vibe. you can get the mdv used for 120 bucks but im too poor to buy one. I really need to get this going if I can.  but this build is just off, i was so eager to use a phase type effect last night , but after today concluded this aint worth it ..rather use a dod phase 45 from musicians friend for 35 dollars