SOLVED Blue Sheep No Effect

[joelorigo]

I'm testing my in-progress Blue Sheep in my Auditorium Test Platform, I am getting a bypass signal, but when switching to Active, there is a "pop" but then no signal. I have continuity between the Test Platform and the PCB on all the connections, I don't see any solder bridges and the Platform was working earlier when I tested another circuit. Can someone take a look?

 

[joelorigo]

Is the output pin on the IC shorting out to ground or to another part of the board?

Just to be clear, the output pin in question is 2, correct?

 

[Laundryroom David]

https://www.ti.com/lit/ds/symlink/tl072.pdf

 

[Laundryroom David]

Just to be clear, the output pin in question is 2, correct?

Output pins on a TL072 are pins 1 and 7

 

[joelorigo]

I see. But looking at the schematic, doesn't the signal go out of pin 2, down the path to ground on the left, and also loop back into meeting up with the output of 1? As I stated above, I'm a novice at reading these and trying to understand it better.

 

[Laundryroom David]

I see. But looking at the schematic, doesn't the signal go out of pin 2, down the path to ground on the left, and also loop back into meeting up with the output of 1? As I stated above, I'm a novice at reading these and trying to understand it better.

No problem. I would try at pin 1.

 

[joelorigo]

Is the output pin on the IC shorting out to ground or to another part of the board?

The only pins that have continuity with ground is 4 & 8, which looking at the power section of the schematic looks normal

Gently remove the IC from the socket and bend the audio output pin so it does not fit into the socket when you put it back in.
Then power up the circuit and use your audio probe to see if you are getting audio output on the pin you kept from going back in the socket. If you have audio on the pin, but not when the pin is in the socket, you check the parts that connect to that pin on the PCB to isolate where the audio is being blocked/shorted to ground.

I removed IC 1, bent pin 1 up and put it back in the circuit. Pin 1 does not have the signal.

 

[zgrav]

do you have another IC of the same type that you can put in that socket to see if it works?

 

[joelorigo]

You can also test for connectivity between parts. Disconnect the pcb from power, then try testing between various points.

A great start would be between power and ground , to make sure there’s no short circuit anywhere.

I am not getting any continuity between the power or any of the ground points.

 

[joelorigo]

do you have another IC of the same type that you can put in that socket to see if it works?

This is a chip that I tried in another build, that build worked with it in.

 

[joelorigo]

You can also test for connectivity between parts. Disconnect the pcb from power, then try testing between various points.

I am getting continuity between pin 2 and one lead of the 47p cap, one lead of resistors 1.2k & 15k, but not the 220n cap , nor any lugs on the PRE pot.

 

[jesuscrisp]

The only pins that have continuity with ground is 4 & 8, which looking at the power section of the schematic looks normal

It's NOT normal to have the power pin (8) have continuity with ground.
If that's the case, you're not getting power.
I have a feeling that shorting your power to ground by connecting the SW wire to the Auditorium.

Please measure voltage on all pins of the ICs against ground.
It should be close to 0V on pins 4, close to 9V on pins 8 and close to 4.5V on all other pins.

For audio continuity testing, what are you using for that specifically?

 

[music6000]

With Power Unplugged!
Test for Continuity on these matching colours.
Test to see if Red Circles have Continuity with Green Circles?
If you do, you have a short! :

 

[joelorigo]

It's NOT normal to have the power pin (8) have continuity with ground.
If that's the case, you're not getting power.
I have a feeling that shorting your power to ground by connecting the SW wire to the Auditorium.

It previously to unhook the SW wire from the Auditorium, disconnecting the SW wire from the platform gave me signal in bypass still, and a loud hum when switched to Active. I do have continuity with the SW and the GND now btw.

Please measure voltage on all pins of the ICs against ground.
It should be close to 0V on pins 4, close to 9V on pins 8 and close to 4.5V on all other pins.

0 on all IC 1 pins

For audio continuity testing, what are you using for that specifically?

I have this DMM

Cen-Tech 11 Function Digital Multimeter with Audible Continuity - Cen Tech - Amazon.com

Cen-Tech 11 Function Digital Multimeter with Audible Continuity - Cen Tech - Amazon.com

www.amazon.com

 

[joelorigo]

With Power Unplugged!
Test for Continuity on these matching colours.
Test to see if Red Circles have Continuity with Green Circles?
If you do, you have a short! :

View attachment 56302

All the greens have continuity, all the red have continuity, and the purples have continuity.

But so do greens and reds.

 

[jesuscrisp]

Then your power and ground are shorted.

 

[joelorigo]

I have a feeling that shorting your power to ground by connecting the SW wire to the Auditorium.

Also, why are you suspecting that? Just curious, does it have something to do with the fact that this PCB doesn't have LED pad on it like all the PedalPCB boards do?

 

[joelorigo]

Then your power and ground are shorted.

OK, what should I do now to figure out why that is happening? I did another visual check of the soldering looking for bridges and don't see anything really wonky, except on one side of the 33k resistor. It's bulbous, as opposed to a Hershey's kiss. Could that be causing the short?

 

[jesuscrisp]

Whoops, some of my original sentence was deleted. My suspicion was that you might have killed some component by shorting the power to ground by connecting the SW pad without an LED connected.

The SW pad connects the negative end of the LED (with a current limiting resistor in series) to ground so the current can flow and the LED goes on. Without an LED + resistor connected it just shorted Power to ground, you can Google what happens when you do that.

Did you measure 0V at all pins of the ICs with power connected? Because before you measured 9V....

 

[joelorigo]

Did you measure 0V at all pins of the ICs with power connected? Because before you measured 9V....

Sorry, you're right. 0 at all pins connected to power when switch is on Active on the test platform. When in Bypass, 0 on pin 4, 9.23 on pin 8, and around 4.5 -ish on the rest of the pins. For both ICs.

 

[joelorigo]

Whoops, some of my original sentence was deleted. My suspicion was that you might have killed some component by shorting the power to ground by connecting the SW pad without an LED connected.

The SW pad connects the negative end of the LED (with a current limiting resistor in series) to ground so the current can flow and the LED goes on. Without an LED + resistor connected it just shorted Power to ground, you can Google what happens when you do that.

Sounds like I shouldn't have tried this one on the test platform then, yeah? At this point should I finish the build with the in the enclosure, or is there something to do while it is still in the platform?