Marshall Guv’nor/Guvernator- no sound

[megatrav]

Got this guy all wired up. I tried to make it as neat as I could.
The pedal powers on but there is no sound bypassed or engaged.
I am thinking I either goofed on the switch or jacks.
Here are some pics.
Any help is much appreciated

 

[zgrav]

if you have any wd40 you could also try putting a drop in the screw and maybe a drop on the pot shaft and leave the pedal upside down for a half-hour or so. you can also try forcing the pot at both ends of its rotation to see if you can loosen the screw a bit.

 

[Chas Grant]

What type of knob did you use?

 

[PJS]

Last time I had this happen I got the knob off with a cut off wheel in a Dremel. I did not save the knob, but decided that was easier to replace than the pot - I had bought a 10 pack of knobs so had spares.

 

[megatrav]

I am using Marshall style silver top knobs. The spoons and wd-40 did not work. I was able to cut through some one the knob, but I don't have a Dremel. I may try to drill through it tonight.

 

[Chas Grant]

Good Luck! Hopefully it goes well, I was going to recommend cutting them, but it seems you have started that!

 

[zgrav]

did you over-tighten the screws on the knobs and strip the slot? there are also some special drills bits you can get to remove screws, but sacrificing the knob is likely to be the cheapest and quickest solution. Some interesting ideas about removing stripped screws in this video.

 

[megatrav]

did you over-tighten the screws on the knobs and strip the slot? there are also some special drills bits you can get to remove screws, but sacrificing the knob is likely to be the cheapest and quickest solution. Some interesting ideas about removing stripped screws in this video.

Yes, I over-tightened it like a dummy. Thank you for the video. I could cut through the knob which would take a while, but I am hoping I can just drill through the screw enough to get an allen key in there and loosen it enough to pull the knob off. I already ordered some replacement knobs so I am ready to sacrifice it! I hope I can save the pot, but if not, then I can get another.

The way I had this one laid out, the pot wasn't attached to the board so that part is easy

 

[HamishR]

Marshall knobs are always a pain. They get stuck, they split, the screw gets jammed...I'm not sure what it is. I think the plastic is a more brittle form or something. I rarely use them. I just put some on an amp and was surprised it went smoothly. Hopefully I'll never have to remove them.

 

[megatrav]

So, I managed to drill through the knob and get it off. I wired everything up and now I have another problem. The effect is turning on and all LEDs are lighting up but there is barely any output. With all knobs turned up it barely puts out any signal. I can tell the effect is working but something is making it very quiet. The bypassed sound is just fine.
I am going to check all of my solder joints and make sure that I done have any cold ones. Any other suggestions?

 

[PJS]

Measure the voltages on the IC would be the first thing. The second would be to make an audio probe and go through the audio pathway with it and have a listen to where you lose volume. If the gain knob gives you more or less distortion then the volume loss will be towards the output end of the circuit.

 

[music6000]

Did you remove the Knob with the stripped screw out of the Enclosure ?
I ask this as you may have cracked the pot board going inside the Pot while handling it under pressure.
This could cause the lack of volume you are getting now.

 

[megatrav]

I removed the knob by drilling through the screw with the smallest bit that I had. I do have some small marks on the shaft of the pot, but it is still functioning. But I could have damaged it possibly
The gain control, tone controls, and volume control all work, they are just very quiet.

 

[Chas Grant]

Its possible that with all the fun you had with the one potentiometer that you damaged it. Its possible to move the shaft in the pot, I have done this before, I had low volume and intermittent breaking up when turning the pot. Somehow the shaft was pressed down into the pot a little and the wiper was not making good contact with the windings. I opened the pot up by gently opening the 4 tabs on the top of the pot and removing the bottom cover. I was then able to push the shaft back into the pot and it stayed with no problems. Still using the same pot to this day. Or you can try replacing the pot. ( I did this because I 'm curious and like to know how things work, what better way to learn then by trying to break them.)

 

[megatrav]

I went through and reflowed basically every solder point on the PCB and the issue remains. I am going to replace the volume pot and hope that fixes it. If not, I'm giving up haha

 

[megatrav]

Sorry for the late update. I replaced the volume pot. No difference.
the pedal “works” but isn’t even audible unless the volume is maxed out. At that point it’s less than half the volume of the bypassed tone.

I can’t read schematics very well, so I’m not sure what would be problematic. If anyone has any more suggestions, please feel free to advise!

 

[megatrav]

When I look at the schematic, I do see R11 and c12 after the volume pot. When I look at the board, those look like they have nice solid shiny solder joints. The only thing I can figure is that I may have used the wrong value?

 

[Chas Grant]

Looking at the build docs, the pic on the web page for the PCB and the pic of your build, I see a few discrepancies. Check and see if you can see the values printed on the PCB with out removing the resistors, if not you may have to do continuity checks to verify them. The circled resistors are the ones in question and the color code value is next to them. Mr. PedalPCB usually says to go with what is printed on the PCB as these are the most up to date.
Circle color What you have installed What it is According to web page/Build DOC
Red 10K R11 - 22K
blue/green 22K R8 - 100R
pink 47K R4 - 10K
Orange 680R R102 - 47K
White 100R R10 - 680R

YOU NEED TO VERIFY THE VALUES TO YOUR BOARD!

 

[megatrav]

Looking at the build docs, the pic on the web page for the PCB and the pic of your build, I see a few discrepancies. Check and see if you can see the values printed on the PCB with out removing the resistors, if not you may have to do continuity checks to verify them. The circled resistors are the ones in question and the color code value is next to them. Mr. PedalPCB usually says to go with what is printed on the PCB as these are the most up to date.
Circle color What you have installed What it is According to web page/Build DOC
Red 10K R11 - 22K
blue/green 22K R8 - 100R
pink 47K R4 - 10K
Orange 680R R102 - 47K
White 100R R10 - 680R

YOU NEED TO VERIFY THE VALUES TO YOUR BOARD!

View attachment 8441

Hey thanks! That looks to be my issue. It might take some time, but I will swap with the correct ones. Hopefully that fixes it!

 

[megatrav]

So, I managed to get the incorrect resistors out.. or at least the ones you highlighted.

As I was taking the resistors out, I noticed that they are marked with the incorrect value on the board, which is most likely how I mixed up the values so badly. I have no idea if there are others that are incorrect.

It is definitely my fault for not checking and verifying the build doc with what was on the PCB, but I do think @PedalPCB might want to consider either including a warning that the values aren't the same or maybe not have the incorrect values on the board lol

 

[Chas Grant]

So, I managed to get the incorrect resistors out.. or at least the ones you highlighted.

As I was taking the resistors out, I noticed that they are marked with the incorrect value on the board, which is most likely how I mixed up the values so badly. I have no idea if there are others that are incorrect.

It is definitely my fault for not checking and verifying the build doc with what was on the PCB, but I do think @PedalPCB might want to consider either including a warning that the values aren't the same or maybe not have the incorrect values on the board lol

GO WITH THE BOARD!