Lemon Rockerverb- no sound when engaged

megatrav

megatrav

Well-known 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!
 
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megatrav said:
I would consider taking them out and putting in different ones but I don't think that is the issue. Maybe a trace is damaged somewhere?
Click to expand...
This is why I have asked if anything was removed from the Original Build up.
This is crucial as not knowing the quality of the board, any removal of any part in the original building of the Board could have damaged a trace.
This is why temol suggested the audio probe. this will tell you from the In to the Out highlighted in RED on the Schematic he supplied where the audio stops along the way is an Issue.
You listed C4, Is that still an Issue?
Q1 Drain is ??????????????
If so, Reflow it & Test again!
 
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The only things I have removed
music6000 said:
This is why I have asked if anything was removed from the Original Build up.
This is crucial as not knowing the quality of the board, any removal of any part in the original building of the Board could have damaged a trace.
This is why temol suggested the audio probe. this will tell you from the In to the Out highlighted in RED on the Schematic he supplied where the audio stops along the way is an Issue.
You listed C4, Is that still an Issue?
Q1 Drain is ??????????????
If so, Reflow it & Test again!
Click to expand...
Okay to clarify, the only component I have removed from the original build is c10.

I get continuity when testing from the leg of the component on the adapter board to the corresponding pads on the adapter board and the back side of the main PCB. There is no continuity between each leg of the transistor (Q1). When using an audio probe, I can hear the audio when I touch Gate of Q1 but not the Drain or Source. Also, when I touch c4 I do not hear audio.

I'm not sure what I need to test at this point, I am doing my best to keep up with both yours and temol's instructions.
 
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megatrav said:
The only things I have removed

Okay to clarify, the only component I have removed from the original build is c10.

I get continuity when testing from the leg of the component on the adapter board to the corresponding pads on the adapter board and the back side of the main PCB. There is no continuity between each leg of the transistor (Q1). When using an audio probe, I can hear the audio when I touch Gate of Q1 but not the Drain or Source. Also, when I touch c4 I do not hear audio.

I'm not sure what I need to test at this point, I am doing my best to keep up with both yours and temol's instructions.
Click to expand...
As temol has stated, You need to Test if you have Continuity from Transistor Legs to the Legs going to the Main PCB
Start with Q1 as that seems to have an issue :
Continuity from Transistor to Legs.jpg
 
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WAIT!

I forgot that I originally had the trimpot for the Gain+ and the trimpot for Q1 mixed up and I did have to remove them/swap them.
So, it is possible that I messed something up when I did that swap. How can I test?
 
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megatrav said:
WAIT!

I forgot that I originally had the trimpot for the Gain+ and the trimpot for Q1 mixed up and I did have to remove them/swap them.
So, it is possible that I messed something up when I did that swap. How can I test?
Click to expand...
Highly possible!!!
You said that Q1 trimmer adjusts so you have 4.5v, Is this still true, TEST AGAIN!!!
 
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I don't care to read through 6 pages of troubleshooting at this point but I would like to point out that this circuit is poorly designed with regards to the placement of the tone stack, volume pot, and the output. I strongly suggest acquiring a small buffer for insertion between the output of the circuit board and the stomp switch and see if that improves the overall sound as I suspect you're going to run up against impedance issues with the way that is drawn up in the build documents
 
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thesmokingman said:
I don't care to read through 6 pages of troubleshooting at this point but I would like to point out that this circuit is poorly designed with regards to the placement of the tone stack, volume pot, and the output. I strongly suggest acquiring a small buffer for insertion between the output of the circuit board and the stomp switch and see if that improves the overall sound as I suspect you're going to run up against impedance issues with the way that is drawn up in the build documents
Click to expand...
He can find that out for himself if it Fires up !!!
 
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Troubleshootign is getting harder and harder with every step here. Too many variables.
- you have a signal on Gate of Q1 - where exactly? capacitor in front of the G? Solder pad of the socket? inside the socket? solder pad on a daughterboard? Transistor leg? Can you swap places q1 and q2?
- do you have 4.5V or 1/2 of the Vcc on a Drain?
 
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Okay I'm sorry this became a 6 page thread.
My voltages are all over the place now.
I swapped the trim pots because I couldn't get it low enough to 4.5v. Now, when I test Q1 the lowest I can set the voltage is 6.3.

I think I am going to put this one on the shelf for at least a few days and move on.

It was fun learning ways to trouble shoot issues but this has gotten to the point of frustrating.

Maybe this one is just a terrible design or maybe I messed it up. Or maybe the jfets I have are bunk. I have no idea.

Thanks for all of the replies. I will report back if I'm able to find anything else out
 
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megatrav said:
Okay I'm sorry this became a 6 page thread.
...
Click to expand...
No need to apologise.

Plenty of other troubleshooting threads have surpassed the six page mark, and besides... the purpose of the Troubleshooting Sub-forum is to to troubleshoot.

While I wasn't able to be of much assistance, there's been plenty of good guidance from better minds/more experienced people; sharing the experience potentially benefits others — so whether a 2-page thread or a 10-page thread, it has value.

I have a vested interest in your success, as I have the same PCB waiting to be built.

Putting this project down for a while might be just what is needed to be able to gain a fresh perspective and potentially bring the thread to positive fruition.
 
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Feral Feline said:
No need to apologise.

Plenty of other troubleshooting threads have surpassed the six page mark, and besides... the purpose of the Troubleshooting Sub-forum is to to troubleshoot.

While I wasn't able to be of much assistance, there's been plenty of good guidance from better minds/more experienced people; sharing the experience potentially benefits others — so whether a 2-page thread or a 10-page thread, it has value.

I have a vested interest in your success, as I have the same PCB waiting to be built.

Putting this project down for a while might be just what is needed to be able to gain a fresh perspective and potentially bring the thread to positive fruition.
Click to expand...
Good Luck trouble shooting this one, the GAIN Pot is on the Top Right outside of the Main Schematic!
 
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Thanks everyone for the encouragement. I am at least taking the weekend off from building/working on anything.
I was really hopeful that this would be my answer to not buying a Rockerverb but as many have stated, the circuit itself is flawed.

I think that maybe GuitarPCB Mania projects aren't as great overall. I am also building a "Sea Lion Compressor" from them and it has been a headache as well
 
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Just a little update.
I removed the boards with the jfets and installed some other ones direct on the pads. I am still not getting audio but I am getting the LED turning on and off with the switch.
I also have bypassed signal still. Just nothing when engaged.
I am going to do some testing with the audio probe tonight or tomorrow.

If it appears to still not work, I am going to cut my losses and probably just order a new board at some point.
Here is a pic of the transistors on the board.

D1180250-B5E2-4839-AE55-3DD61E65BC3C.jpeg
Please excuse the marred capacitors. It was a tight spot
 
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