**FIXED** Collosalus 2022: Signal and Voltage Issues

[jeffwhitfield]

Hey folks,

Just put this one together and, after running initial tests and traces on the board, I immediately started noticing some oddities. I'm usually pretty good at debugging drives and fuzzes. It's the other stuff that I have a problem with. Did a full inspection, touched up a few spots with solder, but still can't figure it out.

I'm getting a signal off TP1, but it's a bit distorted. No signal off TP2 at all. Voltage readings off the first few IC's check out fine. However, once I got to IC3 (MN2007), I started getting some wildly different voltages than what's expected. Same with IC7 (CD4013BE) and IC8 (CD4049UBE).

Attached are pics of my board as well as the voltage measurements. Any help in debugging this sucker would be most appreciated. Just need to be pointed in the right direction.

Thx in advance!

[jeffwhitfield]

Quick update. So my audio probe is totally hosed. Seems that it just causes a constant hum when in use so...ordered a pre-made audio probe from Rattlesnake Cables. Once I get it, I'll resume debugging and, hopefully, will find where in the signal path everything is breaking down.

[Scruffie]

No clock (1/2 supply on pin 2 & 6 of 3007 when working) = no BBD signal.

4013 and Q3-5 are where you have to dig.

[Thewintersoldier]

Quick update. So my audio probe is totally hosed. Seems that it just causes a constant hum when in use so...ordered a pre-made audio probe from Rattlesnake Cables. Once I get it, I'll resume debugging and, hopefully, will find where in the signal path everything is breaking down.

Is this your first audio probe or probe usage? Generally you get nothing but hum/noise until you hit an audio signal. I'm not sure how your probe would break unless a wire broke or a solder joint was bad since there are no active parts in a probe. At the very least there should have been signal at the input.

Sent from my Pixel 5 using Tapatalk

[jeffwhitfield]

Is this your first audio probe or probe usage? Generally you get nothing but hum/noise until you hit an audio signal. I'm not sure how your probe would break unless a wire broke or a solder joint was bad since there are no active parts in a probe. At the very least there should have been signal at the input.

Sent from my Pixel 5 using Tapatalk

It's not my first probe. The current one is an sProbe I put together. And, yeah, even with the ground attached and probe hitting an active part it still results in hum/noise. Switched out the capacitor but, nope, still not having it. I'll likely play with it later, debug it, and get it working as a backup. But, for now, I just need a working probe.

[Thewintersoldier]

If you don't wanna wait
http://diy-fever.com/misc/audio-probe/

[jeffwhitfield]

True, true. Built one of those prior to building an sProbe. New one will be here by Friday anyways so I can wait.

[Bio77]

Try wiggling Q3-Q5, one might be loose in the socket.

[jeffwhitfield]

Try wiggling Q3-Q5, one might be loose in the socket.

Will do! Probably need to test those transistors to make sure they're good. They were from a know good batch but...hell, could be a bad one in there.

[jeffwhitfield]

Ok, got a working probe. TP1 works. TP2 doesn't. Going off IC3 (MN3007), pin 3 is getting a clear signal in. I would assume that I would get a signal off pin 7 and 8. Nope.

I tried switching out the Xvive chip I got for a MN3207 which technically should still work, albeit not well. Nope. Might go ahead and order another MN3007 to see if maybe I just got a bad chip.

Other things I did: reflowed all the solder joints; removed, tested, and reseated all transistors

[Bio77]

BBD is probably fine.  You don't have a clock.  You should follow Scruffie's advice.  He's the Yoda of BBDs 

[jeffwhitfield]

BBD is probably fine.  You don't have a clock.  You should follow Scruffie's advice.  He's the Yoda of BBDs 

Good advice!

Ha! Yoda of BBDs! That's awesome!

[Scruffie]

I tried switching out the Xvive chip I got for a MN3207 which technically should still work, albeit not well.

Sorry to have to tell you, but you've killed or at the very least damaged that 3207 now.

A 3207 has inverse power and ground requirements and a maximum supply voltage of 12V (or is it 11?)... you have to account for that when swapping them.

[jeffwhitfield]

I tried switching out the Xvive chip I got for a MN3207 which technically should still work, albeit not well.

Sorry to have to tell you, but you've killed or at the very least damaged that 3207 now.

A 3207 has inverse power and ground requirements and a maximum supply voltage of 12V (or is it 11?)... you have to account for that when swapping them.

Fortunately, that's not the case. Popped the same chip into a know working chorus pedal. Works fine. Guess I got lucky.

One thing is for sure, this whole thing is making me feel stupid. Definitely don't know shit about flanger circuits. Durp!

[jeffwhitfield]

No clock (1/2 supply on pin 2 & 6 of 3007 when working) = no BBD signal.

4013 and Q3-5 are where you have to dig.

Thanks for the tip here. Unfortunately, I'm still bust. I did switch out all the transistors as well as the 4013 (and the 4049 while I was at it). Checked the continuity around that area. Also switched out the two 120pF's I had in place for C23 for a 68pF that measures around 65pF (just for testing). Still no change.

I'll admit, I'm dumb as a stump when it comes to a circuit like this. Can measure voltages, continuity checks, and traces...but no idea on properly troubleshooting a circuit like this. Good with drives, fuzzes, and such. But, man, this is a challenge! 

So...what's the next logical step?