Lemon Rockerverb- no sound when engaged

megatrav

Active member
I've been working on this build from guitar pcb mania.
I have bypassed sound. No sound when engaged but I do have an LED.
I took some shots of the board and I can't spot any bad connections so I think I might have the switch Ground and Control backwards. The PCB only says CNTRL.
I haven't tried swapping them yet but I wanted to post here to see if anyone might catch something else I may have done wrong.
D8E1A375-3995-4E14-B3DE-0B7D22196D96.jpeg 1356B69E-4BEF-4727-9D34-25382E24CF51.jpeg CF32E9F3-AD5D-4D76-9638-E0652C9C6873.jpeg 7C420E8D-B9B7-4F23-987C-2DAC7BFF7725.jpeg
Thanks!
 

megatrav

Active member
What value capacitor do you have at C6 -100pF ?
It's different to C8 & C11 which are also 100pF ?
Those are also 100pf. They are just a different kind of ceramic capacitor. The cheaper ones from Tayda.

An audio probe does sound like a good solution.
Since I am hearing a hum when it is engaged would it be reasonable to think something is shorting to ground?
 

music6000

Well-known member
Those are also 100pf. They are just a different kind of ceramic capacitor. The cheaper ones from Tayda.

An audio probe does sound like a good solution.
Since I am hearing a hum when it is engaged would it be reasonable to think something is shorting to ground?
Think, was the Electrolytic Capacitor the only thing you desoldered & turned around 2 times?
I ask this because if you removed a component that was awkward to remove, you may have damaged a trace!
The + & - Power pads on the PCB look really close to touching, Confirm you don't have Continuity there!!!!!!!!
An audio probe is your only option if you are convinced your components & solder are Good!
 

megatrav

Active member
Think, was the Electrolytic Capacitor the only thing you desoldered & turned around 2 times?
I ask this because if you removed a component that was awkward to remove, you may have damaged a trace!
The + & - Power pads on the PCB look really close to touching, Confirm you don't have Continuity there!!!!!!!!
An audio probe is your only option if you are convinced your components & solder are Good!
I have some solder wick and smaller solder coming in.
I am going to try to redo some of my joints just to be sure.

I only removed the capacitor once. It was the only component I removed, but I will check everything close by to make sure it's good.

I will also check continuity at the +/- pads.

Thanks again for all of the tips. I will report back after
 

megatrav

Active member
Checked and no continuity with the +/- pads. i assume that is a good thing.
I do have continuity between most of the grounds ( I didn't test them all)
I touched up a few pads but didn't have time to test. If it still isn't working, I may try swapping the SMD J201s for some through hole JFETs that I got from Mouser.
I am waiting for some parts to come in for the audio probe.
 

megatrav

Active member
If you have a guitar cable and a capacitor then you have an audio probe. Any capacitor... 47n...to 1u. Do not waste your time guessing the problem.
okay cool. I thought I needed to attach gator clips and all that. Any helpful diagram for how it should be connected? It would have to be something easily reversed
 

temol

Well-known member
Quick and dirty audio probe.

White wire - connect to GND (solder to PCB GND for example).
Yellow wire - signal. Poke different areas of the pcb.. follow the audio path from input jack towards output jack.

If you do not have a jack socket you can open jack plug and temporarily solder cap and GND wire inside jack.
Connect the opposite end of the guitar cable to amp/headphone amp.. set vol almost to zero.


IMG_20211004_193859.jpg IMG_20211004_194218.jpg
 

temol

Well-known member
I assumed it's obvious that you have to inject a signal into the input.. anything.. mp3 player, phone, 1kHz sinewave (signal generator, audacity). Guitar is not the best choice because you probably need two hands to comfortably operate the audio probe.
 

megatrav

Active member
I assumed it's obvious that you have to inject a signal into the input.. anything.. mp3 player, phone, 1kHz sinewave (signal generator, audacity). Guitar is not the best choice because you probably need two hands to comfortably operate the audio probe.
Okay. So, let's say I use my phone and plug it into the input. Where does the output go? I am asking since I am using the input of my amp with a guitar cable. That cable has a Jack connected like the picture above. Ground connected to the ground of the Jack on the pedal (soldered on) and a 68n cap connected to the tip with a cable for probing.

Would the probe allow me to hear the audio if I find the correct "bridge"?

I'm just having a little trouble understanding how it works
 

Mcknib

Well-known member
Separate

Like this quick one, as stated you don't need the clip on the ground side it's just easier to clip it to a ground point

20200420_174549.jpg

Stick one end of your out cable in the probe jack the other to your amp as normal, ground it and probe the circuit with the probe end

Connect whatever you're using as audio into the in jack I use a looper pedal but you can use anything that plays audio
 
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