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?

 

[Feral Feline]

Faulty Vol pot?

Did you test the pots before putting them in?

I compared your build to Szukalski's and found nothing errant.

You've grounded the power differently, but that shouldn't matter.

I'd reflow all the solder joints where the leads were clipped and
Try subbing out the ICs for a different set.


Sorry, that's all I've got.

 

[joelorigo]

Faulty Vol pot?

Did you test the pots before putting them in?

I didn’t, and never have! What should one do to test a pot?

I compared your build to Szukalski's and found nothing errant.

You've grounded the power differently, but that shouldn't matter.

What have I done differently than that build?

I'd reflow all the solder joints where the leads were clipped and
Try subbing out the ICs for a different set.

I’ll start with the ICs I guess, I recently saw a thread about bad TL072s even from reputable sources

Sorry, that's all I've got.

Thank you for your help!

 

[Feral Feline]

Testing the pot:
Remove it from the build.
Turn the pot all the way to one side, measure the total resistance between leg 1 & 2, then 3 & 2.
Turn the pot all the other way, measure again and it should match up with total resistance above (ex 100k pot should read 100k on your DMM).
Turn the pot half way, measure both sides (ex 100k pot will then measure 50k per side).
That effectively takes care of continuity testing your pot as well. Might seem excessive/redundant/whatever, maybe there are better ways to do it, but that's how I'd approach it.


What you've done differently:
You did...
...Nothing differently! I was looking at the power and grounding cockeyed, and thought you'd done something different with the ground — but it wouldn't have mattered even if you'd done it how I thought!
Je m'excuse!

ICs and reflowing
If the ICs check out okay and you're still getting nothing, then start reflowing solder joints (without the ICs in the pedal). Maybe start with the power, grounds and then the IC sockets. Put known good ICs in and test again. Still no signal, then finish re-flowing all the joints.



Still no signal, then get out the audio-probe.


Signal in bypass with no signal while circuit engaged usually means there's a problem with the switching. Double check your connections — just 'cause you have continuity between two points doesn't mean the two are connected correctly and might need to be moved to the neighbouring connection point at one end... if you know what I mean. If not, I should try to get some sleep — a recurring condition.

Good luck!

 

[szukalski]

I don't see where the SW output is connected to, but bear in mind that it is just straight from the 9V because there's no onboard LED or CLR.

If it's connecting to ground, then you're making a short. Try disconnecting it.

 

[jesuscrisp]

What does the offboard wiring (jacks, footswitch) look like?

 

[joelorigo]

I don't see where the SW output is connected to, but bear in mind that it is just straight from the 9V because there's no onboard LED or CLR.

If it's connecting to ground, then you're making a short. Try disconnecting it.

The SW is connected to the SW on the Auditorium Test Platform

 

[joelorigo]

What does the offboard wiring (jacks, footswitch) look like?

Here is a wider photo

 

[joelorigo]

I swapped out the TL072s and still no signal. However they all have the same code on them (26A83KM) so ??? Is there a way to test the ICs? Or just pull them from working pedals?

 

[jesuscrisp]

Maybe just try disconnecting the SW wire from the platform like @szukalski suggested, see if that does anything.
Definitely doesn't need to be connected without an onboard LED.

 

[joelorigo]

Disconnecting the SW wire from the platform give me signal in bypass still, and a loud hum when switched to Active. I did not have continuity with the SW and the GND before I disconnected it btw.

Also, how important is the IC? I just realized I have 2 NE5532s, one of which I know works in another circuit

 

[szukalski]

Most dual op amps should work. It doesn’t need the SW connected at all.

 

[jesuscrisp]

As I assume that this is your own pcb design, could you share the exact schematic you built it with? Not the schematic it's based on, your own.

 

[joelorigo]

Most dual op amps should work. It doesn’t need the SW connected at all.

Does the loud hum tell us anything when disconnecting the SW wire?

 

[joelorigo]

As I assume that this is your own pcb design, could you share the exact schematic you built it with? Not the schematic it's based on, your own.

My design? Haha, no. Even though I've gotten about 40 successful builds under my belt I'm only a "color by numbers" type builder. This is the Blue Sheep donated to this forum by @szukalski here:

Blue Sheep

This is a fun build which is based on the Blue Pilot by dylan159 over at FSB. That is an attempt to re-engineer the Blues Driver to be simpler and cheaper to build, using IC op-amps instead of a discrete op-amp configuration, and common parts. There are a few of these projects and they're all...

forum.pedalpcb.com

I took the Gerber files and ordered PCBs from JLCPCB. I gave 2 away and have messaged those guys to see if they have built theirs to eliminate the PCB bing the problem. (I also have 2 more to give away if anyone wants one)

 

[joelorigo]

The TL072s I have are good, I just tried each of them in working pedal.

 

[szukalski]

Does the loud hum tell us anything when disconnecting the SW wire?

Not really. The SW is just coming straight after the 1N5187 so it shouldn’t have any affect disconnected. See the schematic here:

pedal-bluesheep/bluesheep_schematic.png at main · szukalski/pedal-bluesheep

Contribute to szukalski/pedal-bluesheep development by creating an account on GitHub.

github.com

 

[szukalski]

Break out the audio probe and start tracing the circuit to see where the signal stops.

 

[Laundryroom David]

My design? Haha, no. Even though I've gotten about 40 successful builds under my belt I'm only a "color by numbers" type builder. This is the Blue Sheep donated to this forum by @szukalski here:

Blue Sheep

This is a fun build which is based on the Blue Pilot by dylan159 over at FSB. That is an attempt to re-engineer the Blues Driver to be simpler and cheaper to build, using IC op-amps instead of a discrete op-amp configuration, and common parts. There are a few of these projects and they're all...

forum.pedalpcb.com

I took the Gerber files and ordered PCBs from JLCPCB. I gave 2 away and have messaged those guys to see if they have built theirs to eliminate the PCB bing the problem. (I also have 2 more to give away if anyone wants one)

I bought Blue Sheep boards from jlcpcb as well. No issues.

 

[jwin615]

Center lug tone pot looks iffy. May have balled above the pad.