SOLVED Low Tide Modulator Noisy and Distorted

[nikyramone]

Hi everyone! First troubleshooting post so please bear with me and keep in mind that I am a noob with just a few months experience building pedals as a hobby (which im really enjoying!).
Anyway, after months gathering parts, waiting and waiting and waiting... and waiting for a single potentiometer I finally managed to gather everything I needed to build the Low Tide!! I was so excited. Unfortunately I can't manage to get this to work and I hope someone has a miracle solution for this. Here a short summary of the situation.

• When disengaged my guitar sounds perfectly fine.
• The first time I tried to plug it I got no sound I and I noticed that I had put the MCP602 reversed (here I freaked out, did I just burned everything doing this?).
• Now I hear sound but when engaged everything sounds distorted and crackly (kinda like the sag knob on the barbershop???). This happens with either mix at 0% or a 100% . It happens in either boost o pad mode and it is extremely sensitive to dynamics, if I play VERY quietly it can almost sound as a normal clean guitar (although never quite there) but if I strum a chord with strength the distortion is beyond this world. (it's kinda cool even).
• Absolutely all combinations of bias and gate keep this problem and as I said the problem remains with variations of pretty much all knobs (mix up, mix down, volume up, volume down...) The good news is that the effect is there so at least I don't think I have friend the randomizer IC yet (I can speed up the lfo, reduce the intensity)
• The bbd is from a reliable source (electric druid) but I only have a bunch of J201 through hole from Banzai.
• I have replaced all IC's and transistors (for the J201 just tried all the other ones from the same bag) for several other options that I had around the house except for the BBD and the randomizer, the problem persists.

Is there any chance that simply replacing the J201 for surface mount could solve this or does the fact that the problem persists with boost off and mix down mean that I have done some terrible, terrible damage?
Here are some terrible pictures, sorry in advance for my terrible soldering technique. Thank you so much for the help!
https://drive.google.com/file/d/1Iu7ioRT0PN41ZpwU6U-BnoN7QF6GNGlB/view?usp=sharing

IMG_20211031_193004.jpg

drive.google.com

1635706193270.jpg

drive.google.com

 

[JamieJ]

There is an original and a revision to the low tide. On mine the LM13700 and the MCP602 are facing the other way. Is that correct for your board?

I had issues with my low tide build and the only way to track down issues on complex builds is to use an audio probe.

 

[nikyramone]

View attachment 17875

There is an original and a revision to the low tide. On mine the LM13700 and the MCP602 are facing the other way. Is that correct for your board?

I had issues with my low tide build and the only way to track down issues on complex builds is to use an audio probe.

Hey, thanks for the reply. I have the very first board (I think I bought it pretty much the day it got released). I was following the PCB orientations when putting the ICs but maybe the issue is there.
The idea of the audio pobre sounds like a good learning experience. I will give it a try next weekend.

 

[Cucurbitam0schata]

You got it - they are not too hard to make on the fly, and you'll learn lots. Good luck!

 

[bowanderror]

If you're getting the issue with the Mix at 0% and 100%, then the input & output stages are your most likely culprits (not the delay/LPG/modulation circuits). An audio probe would definitely identify which stage in particular is the problem.

Have you tested the JFETs to see if they are real & if they are standard J201 DSG pinout? The crackling could also be a result of a poor connection between the socket & transistor leads. I've had issues with poor socket connections when bending JFETs over like that, so you may want to try straightening the legs and re-inserting them into the sockets. You can also use hot glue or tape to hold them in place.

I noticed a possible solder bridge that could be fixed with a quick tap of your soldering iron:

 

[nikyramone]

If you're getting the issue with the Mix at 0% and 100%, then the input & output stages are your most likely culprits (not the delay/LPG/modulation circuits). An audio probe would definitely identify which stage in particular is the problem.

Have you tested the JFETs to see if they are real & if they are standard J201 DSG pinout? The crackling could also be a result of a poor connection between the socket & transistor leads. I've had issues with poor socket connections when bending JFETs over like that, so you may want to try straightening the legs and re-inserting them into the sockets. You can also use hot glue or tape to hold them in place.

I noticed a possible solder bridge that could be fixed with a quick tap of your soldering iron:
View attachment 17935

Thank you! That's exactly the kind of feedback I was hoping to hear. I checked and I think the solder bridge is pretty much an optical illusion because of the shitty picture. This weekend I will invest some serious time in audio probing the entire circuit but I am really hoping it is the through hole j201. I have ordered a bunch of SMD and let's see with those.
About checking DSG pinout. Can I do that with a multimeter?

 

[bowanderror]

Good to hear that wasn't a bridge!

You can determine which is the Gate pin of the transistor by using a multimeter, but not the Drain/Source as they're generally interchangeable in JFETs. That's usually enough to get the pinout though.

Basically, you should get continuity (0 ohms) with the red lead on the Gate and the black lead on either the Drain or Source. If you swap the red & black leads, you should then get non-continuity (OL or 20M+) with the black lead on the Gate and the red lead on Drain or Source.

 

[nikyramone]

Hi everyone! The SMD j201 arrived and now everything works perfectly. I just have to do some finer adjustments now to eliminate noise (which will be a bit difficult now that my cheap screwdriver has obliterated the trimpots).
I guess the lesson is not to use through hole J201 ever again.

For anyone interested the through hole I used were from Banzai.