Optical Tremolo build Error (No sound)

[Perkla]

I just built the optical tremolo with the same components that can be found on the internet, i built the 5 knob version and one IC 4558 and TL072, the LED is flashing just like it should when the pedal is activated but it does not give a damn noice, no matter how i adjust the knobs its all quiet... i have double checked it all and it still not working.. it have a mini trim pot as well... what would be wrong ?

[CynicalMan]

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Are you talking about the tremulus lune? What are your voltages?

[Perkla]

http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Are you talking about the tremulus lune? What are your voltages?

The tremolo i built is from Das Musikding. I am running it on 9 volts

http://www.musikding.de/product_info.php/info/p1831_The-Tremolo---optical-Tremolo-kit.html

[CynicalMan]

I meant the voltages on the active components. Read the debugging thread I linked to, it has instructions on how to post them.

[Perkla]

Well, my english is not very good but i understand a little of it, i am no newbie to building pedals, i have built many peldals before but no tremolo.. this tremolo is the model with negative on the pin in the middle of the DC jack and i have it all good with the voltage and the LED is working properly but i dont have any sound.. i have double checked it all several times, i swapped the film capacitors cus i thought they was not working, still no sound... :S the bypass works great and its all wired up like it should be.

[CynicalMan]

I'm talking about this bit:

Now, using the original schematic as a reference for which part is which (that is, which transistor is Q1, Q2, etc. and which IC is IC1, IC2, C1, and so on) measure and list the voltage on each pin of every transistor and IC. Just keep the black lead on ground, and touch the pointed end of the red probe to each one in turn. Report the voltages as follows:

Q1
C =
B =
E =

Q2
C=
B=
E=

IC1 (or U1)
P1
P2
P3
.
.
.

D1
A (anode, the non-band end) =
K (cathode, the banded end) =

D2
A =
K =

Z1 (zener)
A =
K =

And so on until you get through them all. Having gathered the data, post a tidy list of it on the forum, and you'll most likely have a working effect soon.

So take a multimeter, and post the voltages from all of the pins of the TL072. Don't worry about the 4558 if the LFO's working fine.

[Perkla]

This is the voltages on the TL072

1: 8,78 Volts
2: 7,64 Volts
3: 7,60 Volts
4: 8,10 Volts
5: 7,59 Volts
6: 8,72 Volts
7: 8,72 Volts
8: 9,33 Volts

[CynicalMan]

Ok, the first thing to look at is the reference voltage. R16, R17, and C5 form a voltage divider that should make a 4.5V reference for the op amp. So pins 3 and 5 should be around 4.5V, but they aren't. This means that either there's probably a mistake in the voltage divider or that the op amp is broken.

First, look for soldering errors, bridges, or cold joints in the op amp area. Make sure the TL072 is inserted the right way. Using a continuity (or resistance) meter on your multimeter, make sure that R17 is connected to pin 5 on one side and ground on the other.

If the op amp is socketed, remove it and test the voltage over R17. If it's not at 4.5V, then there's some error in the voltage divider. If it is at 4.5V, try a different op amp in place of the TL072.

[Perkla]

I removed the TL072 and on R17 and pin 5 on the socket to TL072 i have about 4,5 volts, i put in a new TL072 and it is still not working, i have double checked the soldering and wiring several times, still the LED seems to flash like it should on a optical tremolo pedal, does the RC4558 have anything to do with this ? if its broken, shoule the pedal still give nocie ?

[Perkla]

This is the circuit board

[Perkla]

I found the problem, my custom made circuit board had a problem, R17 is suppose to be connected to pin 5 on the TL072 AND pin 4 on the TL072 AND then to ground and thats what i have done wrong in my custom etched circuit, i made a jumper so now is pin 4 and one side on the R17 connected to ground and it works just fine.. sorry for making trouble here on the forum.. it was all my fail.. thanx anyway..

[CynicalMan]

Glad to hear it's working. I just debugged one of these, but I just had to swap out ICs until I found a pair that wasn't burnt out by experimental breadboarding. 

[Perkla]

I am using the same components that most 5 knob optical tremolos are using but i made my own circuit board, i made some small changes to it and it works great, i dont understand how i could fail grounding pin 4 on the TL072 and the resistor, i should of known that have to be grounded or else it will not work at all, so i made a jumper and now it works, and i made the change in my custom PCB layout as well so i dont etch the same misstake again.

[wanchope]

Hi everybody, this is my first post, sorry for resuming an old topic but my problem is really similar to Perkla's.
I am trying to make a tremolo w/rate variable on the fly, inside an old volume pedal case. So I built Das Tremolo kit from musikding inside that case and everything looks ok (double checked all solders etc.), but when the pedal is activated doesn't play any sound. As for Perkla, the led flashes right on time with the LFO, so i guess it should be something wrong with the IC1.
I try to report the values I measured on IC1, but as i'm a newbie I don't know which is to be called P1 rather than P2 P3 etc...so I try to make it clear what I mean in graphics:
P1 4,75       P5 9,54
P2 4,75       P6 4,75
P3 4,53       P7 4,75
P4 0           P8 4,53

Just a little difference vs Perkla's: when the fx is (should be) bypassed, still signal is not 100% dry, i feel just a touch of tremolo mixed in.
Anybody could help me? Any idea?

Thanks in advance