Why is the guitar so good at picking up mains hum or are my guitars wired wrong? I have made two kit guitars a Strat & Les Paul. A similar problem of mains hum with volume position exists on both but the LP has unique wiring so I will just concentrate on the Strat. If the volume is set around 75% it makes the guitar a perfect aerial for mains hum. At full volume there is zero pickup as shown in the picture. Both pictures are 2mV/div so there is almost 10mV of hum. :o Is it my guitar and wiring...

Helloooooo,

I checked the connections twice and also double-checked the values. The numbering doesn't follow the PCB at all because the PCB numbering is buried under the components.

Here the voltages, all measured against circuit ground (not DC adaptor ground), pedal on, switches off, knobs at 12 o'clock

U1
1 4.73
2 4.73
3 4.67
4 0
5 3.88
6 3.90
7 3.90
8 7.77

U2
1 3.82
2 3.82
3 3.79
4 0
5 4.51
6 4.74
7 4.74
8 7.77

U3
1 3.88
2 3.88
3 3.87
4 0
5 3.81
6 3.83
7 3.83
8 7.78

Q1 J175 Pedal ON
D...

Hey Folks. New to this site. I repair old amps and occasionally old pedals.

Trying to understand and get this pedal working correctly.

The pedal is working but I notice the following

The red check LED does not light up. I believe it should be ON when the pedal is active. Or, maybe the older versions did not do this?

When running on a battery I see the full battery voltage at the board.
When running on a wall wort there is a 3V drop at the board which I trace back to the PS adapter socket...

Hello all,

I found an old post in wich a Joyo speaker sim bypass was discussed. The problem i encoutered (beside pcb soldering :lol: ), my JF14 appears to have a different layout............ :roll:

DSCF0321.JPG

Does anyone have a clue how to achieve a speaker sim bypass on this pcb board?

Orignally from this website:
Rollz-5 is a weird experimental modular percussion sequence synthesizer thing. You can patch the different modules together in unique ways and there's many possibilities for fun.
For ease of constructing, I created this pdf of the original documentation images, so that it will be easier for people to print them out at correct scale, and also make it easier to read as a consolidated booklet instead of an assortment of gif files.
Rollz-5.pdf
There is an expensive...

Hi Everyone,

I've just recently been given a Peavey Backstage Plus 35W Solid State guitar amp for nothing, and I'm currently working on it to get it back to a useable state, so, what's wrong with it?

Well, the original speaker is a no-worker but the rest of the amp seems to work fine, I verified this by plugging my pair of headphones into the headphone socket, I get normal sound through my headphones but no sound through the speaker.... :thumbsup

I've managed to find what I think should...

Hello gys, just wanted to share some tries I have done with MK1 TB transistors
I usually use MP41A, MP40, MP40 (the last one been quite leaky works great with MK1 typology)
BUT I tried on Q2 Q3 GT403 transistors, they are crazy leaky (700, to 1500 usually). They need serious biasing but man, they sound great.

Cheers
Ben

Hello guys! 😄
I found this pedal sitting around in my drawer, something I got a while back from a friend who told me it was some kind of overdrive.

The pedal came with one knob missing and no labels at all. I tried to figure out what the knobs do and wrote down some labels I applied, but honestly, I’m not sure if I got everything right since I’m kind of a noob with this stuff...

Could someone help me figure out if my guesses are correct? In particular, I’m really curious about what the two...

I got one of these cause they seemed cool. It sounded alright when I played it so I ended up tracing it to see what was going on under the hood. Going off the other pedals by this brand I'm pretty sure its a clone, not sure exactly what it's a clone of but there are some familiar elements. A TS style soft clipper with switchable asymmetry into a two-band Baxandall followed by a JFET buffer. (Yes, I know there's a gate resistor 'missing' from the buffer, it is not a tracing mistake, and the...

The pedal works perfectly in 8 second mode. However, when I switch to 2 or 1/2, the effect doesn't work. When it kicks in, it basically doubles the signal overtop of the input, i.e. Just makes the sound a little warmer. There are no trails, echos, or repeats. The delay controls don't seem to change anything. The controls all work perfectly in 8 second mode however. I've recapped and swapped ICs. I get the voltages on the 4066 when sliding the selector switch. Interestingly, if I jump pins 3&4...

If I set the guitar volume to less than 95% the pedal seems to tune in to mains hum. The guitar has no hum when plugged into my Zoom 3000 so why would the Boss pedal give trouble? I bought the Boss off Ebay so I did a factory reset that went fine but setting the pedal sensitivity or range of the toe & heel switches didn't do what the manual said. It appeared to log the two positions with the right led states but pressing the switches a second time was supposed to switch it to normal mode. Is...

Hey Everyone,
Been a while since I last contributed a new thread to the forum, anyway, thought I would start a thread about a Tube amplifier I built a few months ago, okay, so what is it? I hear you ask, it's an OTL (Output Transformerless) Tube amplifier I built using three Svetlana 6N1P medium mu twin triode tubes I bought online from Evatco, I built the amp so that I could connect my pair of Audio Technica ATH-M50X headphones to my 43 inch Blaupunkt smart TV, the TV does not have a built-in...

Hi. I built WattAmp pedal. (
It is preamp pedal with 3 transistors. It works great, but even on low gain have some loud noise.
I recorded it. Can anyone classify this noise? What should i check?

I posted the gut shots to this a while back here

The original thread for this was for the first version which was different and the schematic pics are long gone.

I got around to tracing it myself, it's slightly different than a phase 90, just some different part values and an extra resistor on the output. Enjoy.

JoyoVintagePhase.png

Hello guys. Just built UniCab from pedalPcb.
It sounds not bad with guitar. But when i tried it with bass, there was not enough low frequencies for me.
So i want to change values of some filters to just add more bass.

I hear that Size and Resonance pots are changing bass. Am i right that i have to try different values for C8 and C10?