First project not working. Please help !

[sunday_luthier]

Hello everyone,

I'm new here, my name is Ben.

I've buit a few guitars but I am completely new to making stompboxes.  I have no knowledge whatsoever about electronics.  I needed a Reverb pedal but thought it would be a fun project to build my own.  It has turned into a nightmare.

I bought a Musikding 3-Verb kit (https://www.musikding.de/3verb-reverb).  I didn't mod it or anything.  I simply wouldn't know how to.  I just wanted to practise soldering and have a homemade stompbox.

The schematic : https://www.musikding.de/docs/musikding/3verb/3verbschem.pdf
and wiring diagram : https://www.musikding.de/docs/musikding/3verb/3verbwire.pdf

As far as I could tell, I followed the instructions and did everything right. 
But, of course, I didn't.  Otherwise my pedal would be working ;-)

It works sometimes, but most of the time it doesn't.  It either emits a loud distorted sound, or no sound at all.

Here's a clip of what's wrong. 

I read the troubleshooting section before posting here, so I hope the info below is useful.

I measured the voltage on all parts.  Here they are :

GND -- 0.00
Led -- 9.17
9V -- 9.17
In -- 0.00
GND -- 0.00
Out -- 0.00
GND -- 0.00
M1 -- 0.00
M2 -- 0.00
M3 -- 0.00
D11 -- 0.00
D12 -- 0.00
D21 -- 0.00
D22 -- 0.00
-----------------------------

0.00--R1--0.00
1.57--R2--1.60
6.53--R3--6.66
1.33--R4--3.69
3.69--R5--3.67
0.00--R6--0.00
0.00--R7--0.00
1.64--R8--2.99
0.00--R9--0.00
0.00--R10--0.00
7.37--R11--9.18
7.38--R12--3.68
3.68--R13--0.00
9.17--R14--9.17
-----------------------------

1.91--C1--0.00
1.96--C2--6.67
3.67--C3--1.64
3.67--C4--0.00
1.64--C5--0.00
3.67--C6--0.00
0.00--C7--7.37
0.00--C8--4.95
-----------------------------

IC1
0.00   3.67
3.67   3.68
1.88   1.64
6.67   7.36

IC2

1 - 4.95
2 - 0.00
3 - 1.37
4 - 0.00
5 - 0.00
6 - 0.00
7 - 2.56
8 - 2.48
9 - 2.56
10 - 2.48

IC3
4.95 -- 0.00 -- 7.36
----------------------------

   2.99
   
    P1

3.68      2.99
----------------------------
0.00--D1--7.39

If anyone could help, that would be great !  If you need more info, please let me know.

Cheers,

[antonis]

Flip 180^o IC1..

Edit: Nahhh...

[11-90-an]

Flip 180^o IC1..

Edit: Nahhh...

No welcome, antonis...?

Anyway, welcome, ben, to the forum...

Do you have any pictures of your build? If you say that it sometimes works, it may be some cold solder joints...

Those IC1's voltage doesn't make sense... are you sure you soldered the components on the board the right way around? Again, pictures plez...

[sunday_luthier]

Hi,

Thanks for your reply.  I looked into the IC1.  I didn't realise that there was supposed to be a socket for it so I directly soldered it to the board.

I broke a couple of prongs removing it so I had to order a new one.

I noticed there was a bit of a "solder splatter" between the prongs so maybe that was the problem...

I also broke prongs from the IC2 chip, so I had to resolder them...

As I said, it's getting uglier and uglier... 

I'll be sure to let you know when I get the new TL072 chip.

Cheers,

[Marcos - Munky]

Welcome, Ben.

IC1 could be soldered directly instead of using a socket. This really doesn't matter too much, the difference is using a socket makes it easier to be replaced/removed if needed.

When you post voltages, you don't need to measure every part. Usually, the voltage supply and the voltage at every pin of every ICs and transistors are enough, you don't need to measure resistors and caps. And, for the ICs, there's a indication on one ent of a IC, it's a dot on the layout you posted. The pin at top left is pin 1, then 2, 3 and 4. The pin at bottom right is pin 5.

So, by your voltages:

IC1
0.00   3.67
3.67   3.68
1.88   1.64
6.67   7.36

we have (post this way next time):
1 6.67
2 1.88
3 3.67
4 0.00
5 3.67
6 3.68
7 1.67
8 7.36

While it's a smart idea to include the correct voltages within the kit, they didn't included them. But anyway, some voltages are off. Let's start by pin 8.

Pin 8 is the positive voltage input. According to the schematic, voltage goes in, then thru a 33r resistor (R11) where it drops a bit, then goes to V+, which is connected to pin 8 of IC1 and to IC3. But you got 9.37V feeding the circuit, and R11 shoudn't drop it that much. So, either:
a) you measured the voltages the wrong way, which don't seems to be the case because of other voltages (more on that below). You should put the meter on DC voltage, black probe connected to any ground point, and red probe to where you are measuring the voltage.
b) R11 have an incorrect value. Check the color code, it should be orange orange black (plus one or two extra bands which the color doesn't matter).

If we check the voltages on IC3, we have those 7V entering the IC, and the output is about 5V. This is correct, since IC3 5V is a voltage regulator. Also, the voltages on pins 3 and 5 of IC1 (marked as Vb on the schematic) are connected to a voltage divider (R12 and R13). Since those resistors have the same value, the Vb voltage is half the voltage on V+. We expect about 4.5V on those points, which is half of 9V. Since you're feeding the voltage divider with 7.3V and getting 3.6V (half of 7.3V) out of the divider, so the divider is working but the input voltage is wrong. Once you solve the R11 issue, you'll solve pins 3 and 5 voltage issue.

Also, by your photos, some parts aren't really soldered to the board. IC2 for example, pin 3 is soldered to a orange wire but not soldered to the board.

[antonis]

No welcome, antonis...?

Aoutchhhh.. 

[deadastronaut]

the brick is meant to be connected directly to board underneath....(last thing to go on by the looks. )

[ElectricDruid]

Welcome, Ben!

First thing I'd say is "Don't get too disheartened" - stuff doesn't often work first time, even with experience. It just gets easier to fix it is all!
Second thing to say is that I don't think that looks too bad at all. I've certainly seen some much uglier stuff posted around here!! So bear with it and I think you'll get it going.

Someone else pointed out that some of those solder joints don't look like they've flowed properly - there's space around a few of them. Also you could trim off the excess wire on the solder side of the board (Incidentally, when I was a penniless teenager who couldn't afford tools, I used to use a pair of toenail trimmers for this job! Sidecutters on a budget!). Long ends like that are asking to bend over and short against something else, or short on the enclosure or something.

Once you get the new TL072, get that socket soldered in, fix up a few of those dodgier-looking joints, and we'll have another look at it.

Good luck!

Tom

[duck_arse]

hello sunday, and welcome. that antonis - he has no manners.

about your R11 - I think is right value, orng orng blk silver brn I think is wrong value, shows 3R3, which makes matters worse.

https://resistorcolorcodecalc.com

the current the circuit draws through that value resistor equals the voltage drop from 9V DC input to your measured 7V4 ish. at 33R it would be about 48mA, but at 3R3 it becomes 480mA. this indicates a short somewhere on your board - IF - your voltage measures are measured correctly.

and this brings up point 2 - it is good that you have posted all those component voltage readings in this inst, because there are some resistors connected hard-to some IC pins as sighted on the circuit diagram, meaning both resistor and IC pin should read exactly the same volts. yours don't - I can't match any of your IC readings to any of the resistor readings, to any useful degree.

so, this leads me to ask about your measuring method - could you take us through your proceedure, please? meter type, metter settings, circuit power on or off, probe placements, etc.

[jfrabat]

Welcome to the forum, Ben.

First thing I'd say is "Don't get too disheartened" - stuff doesn't often work first time, even with experience. It just gets easier to fix it is all!

Wait, you mean that sometimes they DO work the first time around?  LOL!  Mine VERY RARELY work the first time around.  But like Tom says, you just get better at figuring out WHY it is not working, and fixes come quicker than before.

Second thing to say is that I don't think that looks too bad at all. I've certainly seen some much uglier stuff posted around here!! So bear with it and I think you'll get it going.

Trust me, Tom is right!  This is one of my first boards posted in this site:



Not pretty at all!!!  In fact, yours is a work of art in comparison!  (In my defense, my soldering has gotten WAY better!  I even dare say I have gotten pretty good at it!)

Regarding ICs, while it is not mandatory to have a socket, it is a REALLY good idea to always do so.  You avoid damage by excess heat, you avoid having to desolder an IC that has been soldered backwards (I have heard from others... I have NEVER EVER done this myself!  ), and you can swap out busted ICs (it is rare, but it has happened to me already).

I also agree with Duck_Arse in that there is something funky with your readings.  Voltages should match at the IC and the component they connect to.  Also, follow Tom's advice: fix up those suspect solder joints and cut off the bottom (solder) side leads close to flush.  You will avoid shorts this way.  And trust me, shorts WILL creep up on you from everywhere (solder bridges, lose wires, signal wires touching the case, etc.)!  You dont want to give them more ways to do so!

[antonis]

I also agree with Dick_Arse

Are you calling Stephen Dick or Arse..??

[ElectricDruid]

I also agree with Dick_Arse

Are you calling Stephen Dick or Arse..??

I'm sure it was just a unfortunate typo, what with "U" and "I" being next to each on the typical QUERTY keyboard...

Still, it *was* unfortunate!

So, Duck, how're y'feelin'? No feathers out of place, I hope??

[jfrabat]

I also agree with Dick_Arse

Are you calling Stephen Dick or Arse..??

I'm sure it was just a unfortunate typo, what with "U" and "I" being next to each on the typical QUERTY keyboard...

Still, it *was* unfortunate!

So, Duck, how're y'feelin'? No feathers out of place, I hope??

It WAS an unfortunate typo (which was fixed!).  Sorry, Duck_Arse!  Stephen has always been very helpful, so I would not classify him as neither a dick nor an arse! 

PS: It was sort of a funny typo though!   

[PRR]

Are you calling Stephen Dick or Arse..??

I didn't think we could say dick on this board??

EDIT -- We can!!

Too late to save Dick Smith or Dick Dale.

[bluebunny]

But we can't have cocktails in Scunthorpe. 

___


Sorry, back to the original programming...

[EBK]

I'm sure it was just a unfortunate typo, what with "U" and "I" being next to each on the typical QUERTY keyboard...

I still have fond memories of an unfortunate typo in my high school typing class (we learned on these massive IBM Selectric typewriters, although there were a few more "modern" typewriters in the classroom that were not deafeningly loud and had built-in correction tape).
The assignment involved copying sentences without looking at the keys or the paper:

Get your camera ready.
Take a quick shot.

I only messed up one letter.

[willienillie]

high school typing class (we learned on these massive IBM Selectric typewriters, although there were a few more "modern" typewriters in the classroom that were not deafeningly loud and had built-in correction tape).

We had 1940s(?) manual typewriters.  No, I'm not that old, this was in the 80s.  Somehow I passed that class, still can't type worth a damn, slow and gotta look at the keyboard.

[sunday_luthier]

Wow, Thanks for all the replies.

I measured voltages by clamping the black thingy from the multimeter to the dc jack ground and poking each contact with the red.
Multimeter was set to V---__.  I'm away for a few days so I'll have to put into practice what I've learned here next week.

Cheers,

[bluebunny]

Yep, that's all good.  The black lead can go on any ground connection: the DC jack is as good as any other.  One of the in/out jacks is another common candidate.

[duck_arse]

I also agree with Dick_Arse

Are you calling Stephen Dick or Arse..??

I'm sure it was just a unfortunate typo, what with "U" and "I" being next to each on the typical QUERTY keyboard...

Still, it *was* unfortunate!

So, Duck, how're y'feelin'? No feathers out of place, I hope??

the feathers of a dick are never ruffled.