No signal from Wonder Drive build

[Jared]

I’m working on a Wonder Drive pedal. I got it all built out and I’m not getting signal through the pedal when the switch is on.
I’ve checked for solder bridges, and made sure all polarity in the separate components are correct.
I’m using a tester and going through the circuit and I’ve come to the point where the signal does not pass through; it’s after the first transistor in the signal. I’ve switched out transistor and the same thing is happening. No signal is coming out of pin 1 and progressing to the next resistor.
I’ve attached a picture to help visualize. (Green is good to go, red is where the signal stops)
Any help would be greatly appreciated!
Thanks!

 

[zgrav]

your hunch is right -- the VCC from the diode should connect to the other VCC parts shown on the schematic.

to test for ground, you DMM should show that all of the points marked ground are connected to one another, and they should also show they are connected to the ground pad on the pcb, and to the ground terminals on the in/out jacks.

 

[Jared]

your hunch is right -- the VCC from the diode should connect to the other VCC parts shown on the schematic.

to test for ground, you DMM should show that all of the points marked ground are connected to one another, and they should also show they are connected to the ground pad on the pcb, and to the ground terminals on the in/out jacks.

To answer your first question: the Power at the IN5817 is (+) is 9.28v and (-) is 9.00v

All of the components that have a VCC indication on them on the schematic are as follows (with voltage readings):
-Q1: pin3 (9.00v)
-Q2: pin3 (9.00v)
-R18: (9.00v)


I'm sorry, I'm new to all of this and I'm still not completely sure if I understand how to confirm if something is actually being grounded as it should be. But I went through the schematic and determined what components are meant to be grounded (indicated by the three line triangle icon) and then tested them with my meter. The results are as follows:
-IN: 0.00v (both pins)
-R1: 0.00v (both sides)
-R7: 3.70v and 0.00v on the other side
-C10: 4.47v and 0.00v on the other pin
-R4: 0.00v (both sides)
-Volume: 0.00v (all pins)
-R21: 3.70v and 0.00v on the other side
-R10: 0.00v (both sides)
-OUT: 0.00v (both pins)
-SW: 0.00v
-C11: 9.00v and 0.00v on the other side

On the schematic, the IC doesn't indicate that any pins are connected to the IN5817 by the VCC icon but here are the voltage readings anyway:
-Pin 1: 4.47v
-Pin 2: 4.43v
-Pin 3: 4.49v
-Pin 4: 0.00v
-Pin 5: 4.47v
-Pin 6: 4.51v
-Pin 7: 4.49v
-Pin 8: 9.00v

After metering I tried the audio probe once again and found that the signal still does not pass through the pedal the same as before.

 

[Mcknib]

Your voltages look good, the voltages you're getting suggest everything in the power supply circuit is working now that the guys have helped sort your inverted power

I've read through your post as far as I can make out you're now getting audio up to pin 3 of the IC? you shouldn't be getting audio on pin 8 (power vcc) so I'm a little confused

Are you numbering the IC pins correctly from 1 top left dot down to 4 then up in a U shape 5 to 8

It might seem like a daft question but are you getting bypass signal we know audios going in but can't see your in and out jacks to make sure out is wired correctly

Anyway here's the main audio path to assist your probing anything coming from a voltage reference e.g. VREF or going to ground may affect audio but isn't part of the audio path, when probing try to probe on the component legs or pins if you can it's not always easy to get a good probe connection on the solder side

Perhaps it's a good idea to re probe following the green trace and update us

The schematic bottom left power section shows connections to the IC pins 8 (vcc) and pins 4 (ground) labelled OPA2604AP you'll see the small 8 and 4 all other pins should be vref half the vcc so as I say all good

 

[Jared]

Your voltages look good, the voltages you're getting suggest everything in the power supply circuit is working now that the guys have helped sort your inverted power

I've read through your post as far as I can make out you're now getting audio up to pin 3 of the IC? you shouldn't be getting audio on pin 8 (power vcc) so I'm a little confused

Are you numbering the IC pins correctly from 1 top left dot down to 4 then up in a U shape 5 to 8

It might seem like a daft question but are you getting bypass signal we know audios going in but can't see your in and out jacks to make sure out is wired correctly

Anyway here's the main audio path to assist your probing anything coming from a voltage reference e.g. VREF or going to ground may affect audio but isn't part of the audio path, when probing try to probe on the component legs or pins if you can it's not always easy to get a good probe connection on the solder side

Perhaps it's a good idea to re probe following the green trace and update us

The schematic bottom left power section shows connections to the IC pins 8 (vcc) and pins 4 (ground) labelled OPA2604AP you'll see the small 8 and 4 all other pins should be vref half the vcc so as I say all good

View attachment 6029

This is very helpful information. Thanks you so much.
Answers to your questions/inquiries:
-yes I’m getting audio up to pin 3 of the IC and nothing after that as far as the audio chain goes. (photo reference attached)
-also, when using the audio probe, I’m getting distorted audio from pin8. It sounds like I have the distortion knob turned all the way up, but adjusting any of the pots does not effect the signal at all. This is also happening on a few of the other components in the power chain.

-I do believe that I am numbering the IC correctly. (Photo reference attached)

-I’ve attached photos of my IN and OUT jacks for your reference.

 

[Jared]

Your voltages look good, the voltages you're getting suggest everything in the power supply circuit is working now that the guys have helped sort your inverted power

I've read through your post as far as I can make out you're now getting audio up to pin 3 of the IC? you shouldn't be getting audio on pin 8 (power vcc) so I'm a little confused

Are you numbering the IC pins correctly from 1 top left dot down to 4 then up in a U shape 5 to 8

It might seem like a daft question but are you getting bypass signal we know audios going in but can't see your in and out jacks to make sure out is wired correctly

Anyway here's the main audio path to assist your probing anything coming from a voltage reference e.g. VREF or going to ground may affect audio but isn't part of the audio path, when probing try to probe on the component legs or pins if you can it's not always easy to get a good probe connection on the solder side

Perhaps it's a good idea to re probe following the green trace and update us

The schematic bottom left power section shows connections to the IC pins 8 (vcc) and pins 4 (ground) labelled OPA2604AP you'll see the small 8 and 4 all other pins should be vref half the vcc so as I say all good

View attachment 6029

Also, something else that might be of note, when I probe IC pin6 or R9 and turn my amp up, I’m hearing some sort of (Vietnamese?) radio chatter. No joke.

 

[Mcknib]

Your IC numbering is correct, still strange you shouldn't get audio on power or ground pins at least I've never come across it

With your voltages on the op amp being ok and assuming you took the voltage readings on the op amp pins and not the solder joints underneath, that would indicate it's good so hopefully something simple like it usually is

I'd make sure your op amp is located into the socket securely if it is, I'd take it out of it's socket and reflow the socket solder joints, as you say they still look a bit rough, just hold your iron on them for around 4 seconds until you see the solder flow onto the solder pad and socket pins, you want your iron temp to be around 400 C

Picking up radio signals isn't unusual in higher gain circuits, in your case more than likely because it's not yet shielded in it's enclosure

 

[Jared]

Your IC numbering is correct, still strange you shouldn't get audio on power or ground pins at least I've never come across it

With your voltages on the op amp being ok and assuming you took the voltage readings on the op amp pins and not the solder joints underneath, that would indicate it's good so hopefully something simple like it usually is

I'd make sure your op amp is located into the socket securely if it is, I'd take it out of it's socket and reflow the socket solder joints, as you say they still look a bit rough, just hold your iron on them for around 4 seconds until you see the solder flow onto the solder pad and socket pins, you want your iron temp to be around 400 C

Picking up radio signals isn't unusual in higher gain circuits, in your case more than likely because it's not yet shielded in it's enclosure

Thank you for the suggestions!

I did take my readings from the pins and not from the socket side.

I went ahead and reflowed all of my solder joints with the 4 second suggestion you gave me and I re-seated the IC.
The audio signal is still bypassing when I switch the pedal on.
and the audio is still being cut off at the same place in the audio path, as well as distorted audio still being heard on pin8 of the IC.

Is it possible that I could have fried the IC when the power was inverted or something?

 

[zgrav]

It is possible your IC is bad, but having the power the wrong way was not likely to harm it. Your diode was blocking most of it. Do you have another IC you can swap out to try?

 

[Mcknib]

The fact your voltages on the IC look good would normally mean it's working but there is a lot going on at IC 1.1 you've got VREF on all 3 pins the only way to know for sure is to try another one

It would be interesting to know what your voltages are for pins 1,2 and 3 on the empty socket

As you know an audio probe just gives you your problem area not what's faulty

You've taught me something, it dawned on me I'd never actually probed pin 8 for audio it being the power pin so I tried it on a wrectifier build and low and behold I got audio at pin 8 on all 3 op amps

We live and learn so thanks for that!

I have had occasion where op amp voltages threw me on a phase 90 repair I got very high readings with the op amp in socket removed the op amp and got good readings on the empty socket so thought faulty op amp swapped it for a new one still got high readings

Eventually I found a bridged resistor which was only active with the op amp in circuit

It being an active device it must have made a connection when in circuit, me being a hobbyist I asked the site expert who said it was rare but theoretically possible

So voltages may look good but don't rule out a component being dodgy or good

 

[Jared]

I’m glad I could lead you to some knew information!
Curious, is your signal distorted on pin8 as well?

Here are my readings on the empty sockets:
Pin1-4.54v
Pin2-4.49
Pin3-4.54v

I will replace the op amp and report back!

 

[Jared]

It is possible your IC is bad, but having the power the wrong way was not likely to harm it. Your diode was blocking most of it. Do you have another IC you can swap out to try?

I will replace the IC and report back!

 

[Mcknib]

Yeah I get a lower volume distorted tone, it was bugging my wee tiny brain so I had to try it

Whilst you're waiting for your op amps I'd check the components in the feedback loop between pins 1 and 2 specifically the B100K dirt pot

As you can see it's wired as a variable resistor without powering the circuit set your meter to ohms place your meter probes on lugs 1 and 2 turn it and the readings should change fully counter clockwise lower resistance, clockwise higher resistance

You won't get accurate readings with all the other series and paralell resistances in circuit but the pot readings should still change

I saw a post recently, can't recall the circuit or details but the problem ended up being a component in the op amp feedback loop not 100% but I think it was a pot

 

[Jared]

Yeah I get a lower volume distorted tone, it was bugging my wee tiny brain so I had to try it

Whilst you're waiting for your op amps I'd check the components in the feedback loop between pins 1 and 2 specifically the B100K dirt pot

As you can see it's wired as a variable resistor without powering the circuit set your meter to ohms place your meter probes on lugs 1 and 2 turn it and the readings should change fully counter clockwise lower resistance, clockwise higher resistance

You won't get accurate readings with all the other series and paralell resistances in circuit but the pot readings should still change

I saw a post recently, can't recall the circuit or details but the problem ended up being a component in the op amp feedback loop not 100% but I think it was a pot

nonsense! Your brain seems to be quite large.
Thank you for more great advice!

from my limited knowledge, the readings seems pretty good:
Dirt b100k= 0 - 102.7k ohm
Tight a50k= 0 - 46.7k ohms

R19= 9.95k ohms
R2= 1.50k ohms
R15 = 4.69k ohms

C7= 128.2k ohms
C1= 171.6k ohms

 

[Jared]

I got a new OPA2604AP and everything works perfectly!

I'm thinking I must have fried the old one when I had the polarity inverted on my AC adapter.

Thank you all for all of your wonderful insight. Ive learned so much through all of this.

 

[Nostradoomus]

Glad it works! It’s a great feeling.

 

[Mcknib]

Great good to hear it

Another good reminder of how voltages are indicators

Good one's don't always mean it's ok and bad one's don't always mean it's fried

I think you did a good job with the info you provided especially with it being rare ish to get good voltages from a fried op amp

I'm sure you'll get many more eureka moments

That's why I love this addiction....er I mean hobby

 

[Jared]

Glad it works! It’s a great feeling.

Yes sir it is!

 

[Jared]

Great good to hear it

Another good reminder of how voltages are indicators

Good one's don't always mean it's ok and bad one's don't always mean it's fried

I think you did a good job with the info you provided especially with it being rare ish to get good voltages from a fried op amp

I'm sure you'll get many more eureka moments

That's why I love this addiction....er I mean hobby

Addiction indeed!
Thank you for all of the info YOU provided! It helped so much.

recommend any good phaser PCBs?