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?

 

[music6000]

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....

On @szukalski PCB's, the SW is + Power.

 

[music6000]

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?

Remove both Op Amps & Test Continuity again.

 

[joelorigo]

Remove both Op Amps & Test Continuity again.

The points in your previous post with the circles?

 

[music6000]

The points in your previous post with the circles?

Yes.

 

[joelorigo]

As before, all the greens have continuity, all the reds have continuity, and the purples have continuity.

But now with the chips removed, the greens and reds do NOT have continuity.

 

[music6000]

I believed you may have fried the chips & it is shorting.
Make sure that SW wire is not connected to anything!
Try a different dual opamp TL072, 4558 in the top spot & see if it corrects the problem with Continuity.
If top one is good , try another good dual opamp in the bottom spot & hopefully that is good with Continuity test.

 

[joelorigo]

I believed you may have fried the chips & it is shorting.
Make sure that SW wire is not connected to anything!
Try a different dual opamp TL072, 4558 in the top spot & see if it corrects the problem with Continuity.
If top one is good , try another good dual opamp in the bottom spot & hopefully that is good with Continuity test.

I removed the TL072s and unhooked the SW wire from the test platform, pulled a TL072 from a working circuit, and put it in the top IC socket. All the greens have continuity, all the reds have continuity, and the purples have continuity - and the greens and reds do NOT have continuity. I put the same chip in the bottom IC socket. Same result.
Then I tried each of the TL072s in a working build and the pedal worked with each of them.

 

[zgrav]

with the chips out of the board, power it on and test the voltages at the points in the sockets where the red circles were drawn. take note of them. then turn off the power, put the working ICs in the sockets, apply power and then take the same voltage measurements at the pins where the red circles were drawn. what are the measurements for each group? any big differences between the measures for the empty sockets versus when the ICs are in place?

 

[zgrav]

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.


0 on all IC 1 pins

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

for your DMM you have "audible continuity testing" which means you get a beep if there is continuity between two points you are touching with the probes. that is not the same thing as "audio testing" which is when you play some kind of signal into the audio input for a pedal and then touch different parts of the circuit with a special probe connected to a speaker so you can tell if the audio signal is reaching the different places it needs to --- eventually to the output jack.

just clarifying that these are completely different things when you are troubleshooting a problem on a circuit board.

 

[joelorigo]

for your DMM you have "audible continuity testing" which means you get a beep if there is continuity between two points you are touching with the probes. that is not the same thing as "audio testing" which is when you play some kind of signal into the audio input for a pedal and then touch different parts of the circuit with a special probe connected to a speaker so you can tell if the audio signal is reaching the different places it needs to --- eventually to the output jack.

just clarifying that these are completely different things when you are troubleshooting a problem on a circuit board.

Yes, no worries, I also have an audio probe that I constructed.

 

[joelorigo]

with the chips out of the board, power it on and test the voltages at the points in the sockets where the red circles were drawn. take note of them. then turn off the power, put the working ICs in the sockets, apply power and then take the same voltage measurements at the pins where the red circles were drawn. what are the measurements for each group? any big differences between the measures for the empty sockets versus when the ICs are in place?

Do this with the SW wire connected back to the test platform I assume? Currently it is disconnected based on above post #66.

 

[zgrav]

I would leave the sw wire disconnected until you get the board working. eliminate it as a possible cause of the issue for now.

 

[joelorigo]

with the chips out of the board, power it on and test the voltages at the points in the sockets where the red circles were drawn. take note of them. then turn off the power, put the working ICs in the sockets, apply power and then take the same voltage measurements at the pins where the red circles were drawn. what are the measurements for each group? any big differences between the measures for the empty sockets versus when the ICs are in place?

Doesn't seem lie a big difference. With the SW wire disconnected from the platform, with no ICs in the board, the readings on the sockets are 9.01 for both. When the ICs are inserted the readings for both pins are 8.91. That is when the test platform is in Bypass and Active btw.

 

[zgrav]

that is what you want to see because you know the power is not shorting to ground like it was doing before. have you checked to see if you have any sound coming through the effect now?

 

[joelorigo]

that is what you want to see because you know the power is not shorting to ground like it was doing before. have you checked to see if you have any sound coming through the effect now?

Great! I have not. Should I check that with the SW wire still unconnected?

 

[zgrav]

the SW wire is just for the LED, right? leave it unconnected until everything else is working. it is a possible source for the problem you had but should not stop the board from working when it is not hooked up to power.

 

[joelorigo]

the SW wire is just for the LED, right? leave it unconnected until everything else is working. it is a possible source for the problem you had but should not stop the board from working when it is not hooked up to power.

I am not sure about that. As it has been described earlier in this thread, I think so. I did try playing through it earlier in this process with the SW wire disconnected and there was signal in Bypass and a loud hum in Active. I can try it again.

 

[Laundryroom David]

I am not sure about that. As it has been described earlier in this thread, I think so. I did try playing through it earlier in this process with the SW wire disconnected and there was signal in Bypass and a loud hum in Active. I can try it again.

I believe

 

[zgrav]

the SWitch wire carries power for the LED so it is not required when you are testing the board. it just lets you know when the effect is engaged when everything is boxed up. you may have a problem the way it is wired but you can save it for last in your troubleshooting.

 

[joelorigo]

Yeah same thing as before, with the SW wire disconnected form the test platform, there is signal in Bypass and a loud buzz/hum in Active.