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Topics - neiltheseal

Hello again, I'm back with another issue that I'm struggling with. Can anyone help please?

I recently built the Keepressor (Keely compressor from PCB Guitar Mania). (build docs

The pedal "works" but not like I had expected. I built a dyna comp which compresses like I expect it to. This Keepressor is very subtle

With an audio probe I have found something that might be an issue, although Im not sure what do do about this.

The signal seems pretty strong up to the base of q3. When I touch many of the parts after this I get signal for an instant which disappears.

D3 - the signal is fine on the cathode.
D4 - signal for a moment on the cathode
Q3 - signal fine on the base, distorted and metallic signal on collector
Q5 - signal on base for a moment, distorted and metallic, but consistent signal on collector
R20 - signal disappears
R21 - Signal fine on one end (connected to pin 3 volume), but on the ohter side same problem as above.
C12 and C13 - Signal disappears

I have checked all of the parts (twice) and they are correct. Transistors and capacitors are oriented correctly.

I had the c5 issue mentioned in the build docs but have fixe this. Once fixed the pedal now works and definitely compresses. The issue is that it is really subtle and most knobs don't audibly do that much.

The pedal sounds ok, but it's a bit of a waste of a compressor at the moment as it is barely noticable. Not like the dyna comp which is very in your face at hight settings.

VOLUME: At full volume the pedal is about unity volume.
ATTACK: turned fully CCW has a mild overdrive sound, that I quite like. Compresses slightly more CCW.
SUSTAIN: seems to work like the sensitivity on a Dyna comp, although it only compresses about 1/4 of a Dyna comp
CLIP: I have no idea what clip does, except for a mild volume boost.

Hi again

I recently put together a Total Bender from PCB Guitar Mania which is 3 tone benders in 1. I managed to get it working with mk3 as a PNP. Link to previous post (

However I have managed to break it and am hoping that someone can assist.

There was too much pressure on the fuzz pot so it only worked at around 10% and 100%. I reflowed solder on the legs of the pot and pushed it out to relieve pressure, however I think i removed the PCB trace rings around the pot so the connection is poor.

An audio signal does come out but it is very faint. An audio probe shows that the fuzz pot is the likely culprit as the audio signal is great until c3.5 on the schematic which is just before the fuzz pot. The signal on fuzz pot and q3 is very quiet.


To repair this, would i essentially solder jumpers from the 3 legs of the fuzz pot to the relevant components? I.e.:
- leg 1 to c3.5
- leg 2 to base of q2
leg 3 to positive end of d1?

Below are pics of the schematic and the PCB. I tried to solder jumpers as discussed but I think i got the legs wrong on the pot. It now does not work at all. Is it 1,2,3 from left to right with the pot facing you?

Also does it matter which leg of c3.5 I solder leg 1 of the fuzz pot to?

Further on the schematic i see d1 and base of q3 are connected. Could I solder leg 3 of the fuzz pot to either of these?
Hello again.

With this forum's help with my previous posts I have successfully completed and/or troubleshooted quite a few pedals.

I was feeling confident however, I have run into an issue with the submarine device by PCB Guitar Mania. I hope that someone can assist with this as I'm a little stumped.

The problem

The pedal sort of works.

  • Works in bypass and when engaged.
  • The volume and voice pot affect the signal as does the switch. I can see the little LED change colour and intensity when the switch/voice pot is adjusted.
  • The switch and voice pots audibly affect the signal
  • However the LED does not throb as I assume it should. The rate, intense and throb pots do not affect the signal

I have checked all of the parts (resistors, capacitors and electro capacitors) and they are correct. ICs and transistors are correct and are placed correctly per the provided build docs. This is assuming the letters at the end of IC names mean nothing. I have TL074CN instead of TL074 and TL072CP instead of TL072.

Pics of both sides of the PCB and my audio probe can be found here (

There seem to be a lot of gaps in the audio probe:
- R3, 4, 7, 8, 10 and 11 and C2, 6 and 7 only had sound on one side.
- VR 2 had audio on one leg but none of the other light dependent resistors had an audio signal. Is this normal?
- The signal seems to come out of pin 1 on IC 2 but I cannot see where it goes in.
- The bottom half of the schematic does not have an audio signal at all but this seems correct.
- I can get the voice pot to adjust the brightness of the red/green LED and the switch changes the colour but I can't get it to throb.

I will reflow solder on all parts tomorrow and see how that goes.

Thanks in advance!

Link to build docs:

Voltage (not sure if it helps):

IC1 - TL072CP
1 - 4.61
2 - 4.61
3 - 2.16
4 - 0
5 - 4.02
6 - 4.61
7 - 4.63
8 - 9.28

IC2 (TL074CN)

1 -  4.84    8 - 4.59
2 -  4.64    9 -  4.61
3 -  4.59    10 - 4.58
4 -  9.28    11 - 0
5 -  3.58    12 - 4.58
6 -  4.61    13 - 4.61
7 - 4.62     14 - 4.61

Q1 (MPSA18)

C - 2.08
B - 0.59
E - 0

Q2 (MPSA18)

C - 1.48
B - 0.89
E - 0.23
Hi everyone. I hope this is the right spot to post this

I just put together a Total bender from PCB Guitar mania. I have managed to get the Mk1 and Mk2 working but am having trouble with the Mk3. I'm hoping someone can help.

This is the silicon version and in the Mk3 transistors are 2n3904.

Currently I can get a very faint signal out of the Mk3 which seems to go to full volume and sound normal when I strum the guitar really hard. Below is a video.

I have asked around and the consensus seems to be that there is an issue with this PCB at least with the Silicon version. I have checked all of the parts are correct and re flowed solder etch and it all seems correct. Plus it sort of works.

Does anybody know what might be the issue here?

Build docs here


- Someone in a facebook group suggested I put a 100nf capacitor in c3.4 where the build docs said to put a jumper. This has helped somewhat and now I get an audio signal (before that there was nothing)
- I put r3.7 (10k) in when the build docs say leave blank as this was in the original schematic.
- Removed c3.9 (470p) as this was not in the original schematic (although I just clipped the capacitor out and didn't remove the legs.
- Reversed the diode (d1) next to q3. I did this because comparing NPN and PNP schematics that they were reversed. My soldering here is bad I know.

For q3 voltage, flipping the diode, adding 10k resistor and removing the capcitor had an effect.
- Previous voltage was: collector is 8.48v, base is now -0.01v and emitter is 0v.
- Current voltage: Collector 4.27, base is 0.16 and emitter is 0

Here are some pics

Thanks in advance!
How Do I? Beginner's Paradise. / Gain pot not working
January 31, 2023, 03:31:13 AM
Hello again. I hope you're not getting sick of me!

I just put together the Aion FX Sapphire (Blues driver standard not the galaxie mod) and am having issues with the gain pot. The issue is that it does not work at all.

The pedal works and sounds pretty goo, all of the other pots work fine but there is absolutely no gain and the pot does nothing. Here is a video of what I mean.

Does anybody have an Idea why this might be?

One potentially obvious solution would be the pot itself. As the build docs ( indicate a dual gang right angled pot, but I could not find one of these so just used a non right-angled one and used wires to connect to the PCB. Although with an audio probe all 6 pins of the pot have an audio signal.

Here are some pics of the inside of the pedal and here is a pic of the schematic with my audio probe tracing. I did not completely audio probe the whole circuit as clearly it makes a sound, however I tried to look around the gain area to see where might be a problem and I am stumped.

I ended up removing the pot and replacing it with 2x 220k resistors and also with 2x 470k and still no gain.

I checked continuity per the image below and it all seems fine.

I even tried replacing the pot with a new pot and still no gain.

If anyone has an idea I'd love to hear it.

Thanks in advance!
Hi everyone.

I just put together an Aion FX Aurora (an MXR Dyna Comp clone). I've never used a compressor before but it seems to work properly, although with one issue.

When the pedal is engaged there is quite a lot of background noise, and when I turn the trimpot clockwise it becomes even louder.
Here is a video of what it sounds like.

Does anybody have any idea why I might be getting this background noise? Here's a pic of the PCB as well as a link to the build docs.
Hello again. I seem to be making incremental progress on my pedals but I am back for more guidance. This forum has helped me fix my last three pedals and I now have seven under my belt.

I have just put together a Death by Octaver from PCB Guitar Mania. I like the sound it makes but there are clearly a couple of issues.

The first issue is that the tone knob seems to work backwards almost. When turned to the left the volume is quite loud and when to the right it is far quieter. Below is a video.

The second issue is that when I roll the gain knob down I seem to get this strange feedback noise. Below is a video of the pedal so you can see what I mean. The feedback is particularly noticeable at the end.

Does anybody know what might be the cause of these issues?

***I did install C3 backwards twice in a row and had to remove it, breaking the metal rings on the PCB. I connected the legs of a 4.7uf capacitor to pin 6 of the IC and pin 1 of the transformer***

You can see both sides of the PCB below and an audio trace I did. I have since reflowed solder after the audio trace.

The build docs are on the link below on page 5

Thanks in advance!
You have been really helpful and helped me fix the last two pedals that I have had problems with.

Well here I am with a third! I recently put together a Theseus from Aion FX (a king of tone clone) and I have managed to get half of it working and sounding great, but only side b.

Pics of both sides of the PCB are below. Side B works perfectly (except for the the LED not working) but Side A does not (the side with no LED).

I did an audio probe and I get a signal on the input of the PCB, one leg of the RPD 1 and one leg of C1. No where else in the circuit. I assume that the signal should be present on both pins of C1 and this is probably the issue. If I re solder C1 and/or replace it with a new one then I should get a signal further into the circuit right?

The build docs are below (schematic on page 7).

Thanks in advance!
Hello again.

You were all so helpful with my previous post with the Tone Bender and now I'm moving onto my next failed project.

I bought the Aion FX Vulcan (Foxx Tone Machine clone) which was labelled as "easy", but i have finished soldering and wiring and it doesn't work. Even the LED won't light up. Although I can hear my guitar's clean tone when in bypass.

I have tried reflowing the solder and used an audio probe to try to diagnose the problem. RE the audio probe, i have attached a schematic where I have highlighted where I can detect the signal and it seems to cut out at C4.

I did make some changes to the components based on what I had available. Maybe these are the issue:
C3- asked for a 100n film capacitor but I used a 100n MLCC
C2- I used a 15n polyester capacitor instead of 15n film
D2 and D3 - I used a 1N34A instead of a BAT 46

Does anybody have any idea what I have done wrong? Hopefully it's an obvious beginner fix.

Thanks in advance.

Build docs below in case anyone is interested
I just put together a tone bender PCB from Tayda. After soldering everything I find that the pedal doesn't work. When I hit the switch the LED lights up but there is no sound. When I turn it off i can hear the clean tone of the guitar.

I'm new to building pedals and new to the forum. I have sucessfully built two kits (one a Tayda fuzz factory and the other an Ali Express Klone) but I am stumped on this.

I followed the instructions provided on their website made an NPN silicon version and followed the suggested instructions (to the best of my ability) such as reversing the polarity of the electrolytic capacitors and putting the 9v+ where it says 9v-.

I'm using BC108 transistors but tried 2n3904 as well. I just don't know where I might have gone wrong.

I have done some research and it seems the problem might be biasing the first transistor, but I have no idea how do do this. Any help would be appreciated.