Recently I built an MXR GT-OD.

W20K is recommended for the tone pot, but I didn't have it in stock, so I made it with B25K.
I know that it is used as a replacement for the W20K in many TS pedals, and I also have a few TS pedals made with the B25K.

However, make my GT-OD with B25K, the tone was too dark when the tone pot was set to 12 o'clock.
I looked for other errors, but there were no special problems, so I purchased a W20K and replaced it.

There has been a big change. It gave me a...

Hi All,

Having a problem I cant solve and I'm not sure what the issue is. Basically I have small tube amp and i'm trying to add a buffered rangemaster circuit to it. To get 9V for the circuit, I tapped off one of the preamp tube supply nodes which sits at 130V. I put that into a voltage divider (R14 and R15) to drop it to 23V, and then put that into a LM7809 ic to provide a regulated 9V. The problem is with that last part, the LM7809.

- with the 7809 installed I get 130V in to the board but...

Hi everyone,

I've been checking this forum for years, but this is my first post here.

So, I tried to add a mono jack to my EHX Freeze to use with an external switch, as instructed in this video (starting at 4:00):

So far so good.

However, my external switch (a mono keyboard sustain pedal) is working erratically.

I mean, sometimes it works when I press it, sometimes it doesn't. It's not practicable.

I check it with my keyboard, and it's working fine.

Does it have anything to do with...

Got my Mosky Silver Horse yesterday. Tried using it and after a day this is what mine does.

Can’t return it coz I sourced it from AliExpress via another country. My mom in law carried it for me. I’ve raised a dispute with AE and written to Mosky as well. No luck so far. Trying some DIY repair if possible.

Any tips on how I should go about this ?

Any checks I can do to figure out what component is causing this ?

Tests I’ve done so far :

D2, D3 and D4 have around 0.6V reading when...

Was anybody successful building a JJ Rocket Boing clone using pedalPCB sproing PCB? I reflowed all my solders, checked for bridges, switched my IC for different kind of opamps without success.
The output gain is way below unity. When plugging a guitar, I get no signal at all (or so low that I can't amplify enough to distinguish it from the static noise).
With an audio probe, I notice that the signal out of the first opamp (pins 1-2 or IC2.1) in the schematic at is already way below unity. Would...

Hello guys,

im having troubles to find what is going wrong with a Truetone Liquid Chorus and Echo Version 1. It was not turning on in the first place but i found a shorted cap close to the DC input, then i could turn on the pedal but it was acting like a bypass even though the leds indicate that either echo or chorus are ON. I found wrong voltages on the 2x 4558 op amp, i replaced them by 2 tl072 and recovered the right voltage on only one of them 4,5V on pin 123 and 567. The other one show...

Anybody know what chip is used in the switching circuit for this pedal?

One is a CD4053, the other the markings are worn away.
I think it looks like a 4013, but it won't latch.

Thanks.

Hello everyone,

I'm moving my post which was initially on the MXR MicroChorus dedicated thread ( here, since it seems to be the proper location for that!

So, long story short:

the MXR MicroChorus uses a SAD512 BBD chip which is hardly sourceable.
Fender3D provided on page 5 a complete rebuild schematic and a PCB in order to use a MN3007 chip instead
Since the original schematic and the updated one are quite close, I just made a small additional board

And now I'm a bit confused!

So...

Thought I'd pick up one of these to see what it's like.
I was hoping I'd be lucky and it would be a take on the Moen Shaky Jimi/Jimi Nova, which are based on the EasyVibe.
Here's links to the Moen Shaky Jimi and Moen Jimi Nova threads.
And I'd like to thank John Hollis for his lovely EasyVibe circuit. :thumbsup

What's inside then? The highlights:
1 x ST 064C
3 x TI TL062C
4 x LED/LDR pairs

It does indeed look to be generally based on the Moen/EasyVibe circuit although I haven't checked the...

I have an old Type P210 tc scf. The gain pot went open and I had to tear it apart to clean and lube the pot. All that done, I did some scoping and measuring and found that it's putting a DC offset at the outputs. The offset starts at 7V (roughly half of 15V) and decreases very slowly. I replaced the most obvious cap and that didn't help. Even when unplugged with a shorted input, it takes about an hour to get back to 0.0V.

The schematics are difficult to read, however, it appears that the...

Hi guys, i have here a musikding Engineering thumbs Compressor kit that is not working!

Schematic:

Guts Shot

Since i’m not the one who mounted the kit, i checked every component polarity etc. resolder a bunch of holes, and identified a wrong transistor in the circuit. It was with a BC337 instead of a BC327.
I changed the transistor, but its somehing else wrong.
I have bypass sound. When its on, seems like there’s no effect applied. Level pot its working , the other ones i can’t notice...

Hi everyone,

I built the Aion P2 (Cygnus) it sounds very good but it is extremely noisy when the volume and sustain control are high (no hum but white noise hiss).
I have already tried several transistors and double checked the wiring and soldering.
Is it normal for the P2 to be so noisy?

Thanks.

Hey,
Just completed a 'Hundo' TA-100 clone on a board from Effects Layouts; using 1N34As and MP42B pnps with HFe tested around 80.

It sounds great *IF* I touch the case of Q2, otherwise it sounds quiet, farty and terrible. It isn't an intermittent issue, just works if I touch it. The other issue was the volume did not work unless I grounded pin 1. I reflowed the Q2 and vol pads but the issues persist.

Any ideas on the touchy transistor? Thanks!

I just picked up this awesome stand alone reverb unit but it doesn’t really work. I’m hoping you guys can help out, might be of interest to somebody.

The unit passes dry guitar just fine, sounds fantastic in fact. I can only get a very weak wet output with the Gain, Blend, and Tone maxed out and hitting the input hard. Hoping for and easy fix I replaced Q5 & Q6 since I heard those two can go bad but there’s no change in operation. I also added C9 since it looked like it had been removed and...

I've made a huge mistake.

I wanted to be able to use the power plug instead of the battery, but the power jack wasn't working. These have a plug style that looks like a headphone plug. I opened it up, made some very minor changes to the power wiring and now that power jack works.

Fast forward a few months and one day my PDS 1700 makes no sound. I try battery power, and plug power, and I desperately try and remember exactly what I changed with the wiring. I don't remember what I did. I have...

Hello,

unfortunately i have a problem with my aion oceanid build. I built the pedal exactly as described in the documentation except for two capacitors C7 + C18. I substituted these with “Styroflex” capacitors of the same value. (This shouldn`t make any difference?).
The pedal works as it should except for there is amplification with all knobs on zero (so the signal is louder when the pedal is turned on). As far as I can tell all the other functions are working therefore there is an increase...

Good afternoon, 

Unfortunately the Empire Big Joe Stompbox of the guitarist from our band is broken.  
He took this pedal over from another musician years ago in good condition, so I suspect no guarantee and since we come from the Netherlands, having it repaired will be an expensive affair.
I have some experience in electronics, and can handle smd components. 
I made a video of the problem, would you like to view this? Perhaps you can explain  what is wrong with the device and give advice how...

Hi all,

I have a Boss CE-1 on the bench.

Symptoms are that the LFO is not oscillating, so the right-hand LED is not flashing - it's on solidly.

Here's the schematic for reference:

I'm not seeing the triangle or sine wave forms on the output of op-amp IC-4b, instead I measure 14v DC. I've removed the chip and put a socket in so I can test alternate chips. Even without the chip in place I see 8v on pin 7, dropping to 2.8V when I adjust the vibrato rate control.

I tried replacing the 1458...

Hi, I have a walrus audio aetos power supply that operates at 230v. Would it be possible to modify or install a new transformer so the power supply operates off of a 120v circuit?

Any recommendations on where to start?
I’ve built a few pedals and an amp from a kit so I have some basic electronics knowledge.

Thanks!

Built RG Keen's Lera from Geofex to add to a PedalPCB clone of the Walrus Julia.

The On/Off switch works and the Lera does affect the sound of the Julia by adding a warble. The speed is quite fast. Neither the ramp up/down switch, the instant/delayed switch, nor any of the three trimpots have any effect on the sound.

I added the optional 10uF capacitor to the output of the 78L05 but no difference to the sound.

The build doc says Once you get it wired up, check it out with a...

Not quite sure how to explain what I'm asking for, but I think it's a Spectrum Analyzer. I have a state variable filter I built and would like to physically see how it's affecting my audio, like with frequency sweeps with the filter. Would something like work so I can plug my bass in, hit a note while playing with the frequency controls and see how the filter is affecting the signal in real time?

Hi, I am needing an (in)sanity check on this project.

I am using the following schematic:
swaw-schem.png

With this PCB that I laid out myself, and ordered for fabrication.
swah-pcb.png

Here's what it looks like currently:
2020_1208_173915_PANO.JPG

My issue is that there is no sound out when the effect is on. I've used an audio probe to come to the following conclusions:

1. The audio going through the LM13700 stops as soon as it reaches the IC.

2. The audio going through the filter...

I have a beloved Boss ME 10 that's giving me some serious problems now.
It's extremely noisy now. Lots of white noise drowning out everything else. There is also a loud crunch/popping sounds every 10 seconds or so. The effects are applied to the noise e.g. if I turn on the delay, the static/white and crunch/pop noise will have a delay to it.
I thoroughly cleaned the board with contact cleaner and a new toothbrush and replaced the 7 caps. It almost seems worse after replacing the caps? I'm not...