Good day L & G,
I was looking for suitable candidate for my bench amp and I found schematic of Roland Jazz Chorus JC-20 from this japanese website :

Looks like this is the one and only JC-20 schematic on the interweb. Anyway, from his article, I got impression that the guy who trace it are surprised that this kind of circuit are released into final products, so probably there's something weird into this circuit.

I did my research based on several another article & gutshot pictures of the...

I went on to try to find a matching pair of diodes for one of my built.
Long story short, I ended up measuring and testing a good part of all odd diodes I have had accumulated over the decades of tinkering.

Some are germanium, some are silicon, including Schottky, etc. I won’t talk about whether any of these sound “smoother”, “warmer”, “rounder”, “fuller”, etc. I don’t believe in tone wood either; nor that a measured 33nF cap will sound different than any other. Disclaimer being out of the...

Hi good folks,

I have the present circuit on my breadboard, and I would like to submit it to more experienced minds to see if there is any major flaw. My knowledge in electronics is purely DIY, on-the-go acquired, so even though my reasoning appears, ahem, reasonable, I'm always afraid to miss something crucial. So far it sounds nice to me, will probably mess with the tonestack and a few other values, but before going any further I hereby submit it here for criticism and observations.

I was...

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...

Maybe I am blind, but how are IC1 and IC2 biased? IIRC the original schem has them at bipolar 15V, but on the build docs they seem to be at 24V-gnd. I cannot see any Vref connection. Will it work as intended without a midpoint bias?
Thx in advance!

Guys,

below some line6 M9 gutshots. I need to opened it to replace a bad LCD and took some pictures.
The M9 schematic is attached as well.
Maybe it help somebody.

Cheers,

Vanderson

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Everything works great!

Except...the LED won't light up.

I cant see why, I've tried different leds, and verified they worked before and after install but I cant get the led to work in circuit.

that's the schematic. I really cant figure out why it wouldn't light up.

Are the inputs and outputs reliant on ground to make sure the led lights up? I'm just using the main I/O not the stereo, there is nothing on those solder pads.

Hello,
As I am an avid cloner myself, I thought that it's my time to give something to the DIY community. I got ahold of the effect mentioned in the title and I am providing some gut shots, also a list with components. Capacitor values on the list have ? due to my lack of experience with SMD components. Where there is no indication on the list will be completed tomorrow then I'll get a magnifying glass. All other info from the list are markings on the components (mostly SMD).
Here are some...

Hi there. I recently picked up this pedal for cheap and I love it. However, it does not quite achieve unity gain when engaged and comes nowhere close unless the eff.level pot is dimed. So even with this pot maxed out, there is still a noticeable volume drop. Its significant enough to cause a problem in live mixes.
I was wondering if there was a simple mod I could make to get to unity? Its all through-hole and I'm comfortable with soldering etc.
As it stands, I have to put a clean boost after...

Bender 1.jpeg Bender 2.jpeg Bender 3.jpeg Bender 4.jpeg JHS Bender Schematic.png

Here is my trace of the JHS Bender. I was interested in the way that he got germanium sound from silicon transistors so I thought I would give tracing it a go. I measured all of the resistors in the circuit, and the values seemed to make sense so I didn't cut any traces. I did however, cut all the traces around the capacitors to measure them so I know they are correct.

While tracing, I removed Q2 in order to...

I am looking for carbon comp 1/4w 1k ohm resistors and am unable to find any online. Can anyone point me to a supplier for these. I really only need one for a pedal repair but figured I would pick up some extras to have on hand.

Thanks,
George