How To Modify Effect Pedals...Designed for the absolute electronics beginner in mind

Written by Brian Wampler

http://www.guitartone.net

Http://www.indyguitarist.com/

http://www.howtoplayguitar.net/

Tools:see 'items to purchase'

For this demonstration, I'll use the sd-1...but by following the directions in this document, you'll be able tomod any pedal!

First thing you'll want to do is unscrew the four screws on the bottom of the pedal, put the screws, the clearplastic and the bottom plate into a small tray or bowl of some sort so you can avoid losing any parts. Forother odd shaped pedals (such as the visual sound), please use this guide with the specific guide for thosepedals (included).

Lift up gently on the circuit board. This is what the inside of the sd-1 will look like

When working with guitar pedals, or any other electronic equipment, its advisable to 'discharge thecapacitors', which means you are bleeding off any stored electricity inside the pedal.

Simply use a screwdriver with a rubber/plastic handle, and touch the solder pads and the pedal case at thesame time. Nothing will happen visually that you can see, but if this were a higher voltage piece ofequipment like a guitar amp, you would see a huge spark and hear a loud POP!

All you are doing here is running a little bitty tiny bit of electricity to ground (which on a pedal, is ultimatelythe case).

DO NOT USE THE SOLDERING IRON TO DO THIS—you will end up messing up a solder joint.

Carefully look over your mod sheet -- locate the first change to be made. You can actually start whereveryou want, but its generally good habit to start from the top.

TIP: On any circuit board, you will see letters and numbers generally (which will be referenced on the modsheet.)If you aren’t sure what kind of part it is, here’s a tip:D= DIODEC= CAPACITORR= RESISTORIC = IC CHIP ( ALSO CALLED OP-AMP)

Q= TRANSISTOR ( I HAVE NO IDEA WHY “T” DOESN’T = TRANSISTOR!)

Locate the part numbers on the pedal's circuit board and the mod sheet. Begin marking the solder jointswith a black felt tip marker (ANY color will do actually!)

TIP: If you mark the wrong capacitor, don’t worry about it – you can leave it alone, or what I sometimes do,is reheat the solder joint just slightly, which will remove the marker. Leaving it won’t hurt anything, it justmight confuse you if you have a lot of markings on your pedal!

When done marking the solder pads, it will look something like this (of course, depending on the specificchanges YOUR pedal requires!)

To remove the current component that will be replaced, you will need your de-soldering braid and solderiron. I highly recommend sticking in a good cd in your cd player to ‘get your groove on’.

My personal fave’s: either misc jazz, Robert Randolph and the family Band, Gov’t Mule, or if I’m in adownright corn-pickin’ mood (I actually do live next to cornfields), I might throw in some Hank Jr.

Before each time you use the soldering iron to replace a component, I like to touch the side of the pedalcase with the soldering iron to discharge static electricity. Static electricity won't hurt you, but it couldpossibly mess up the transistors or the ic chip, though in all actuality, not likely.

Place the face of your de-soldering braid on the solder pad on the circuit board. Apply your hot solder iron toit, for just a few seconds –if it doesn’t soak it all up, pull the iron away, wait about 3 seconds, and try it againwith a clean/new piece of desolder braid.

You will see the soldering braid 'suck up' the solder.

Now, Change the first component on the list. Then, of course, cut the legs off after you solder it (like you doafter each component is installed).

NOTE: On some boss pedals, you will see a bit of yellow epoxy – be careful,and use a needle nose pliers to remove whatever you need to remove to get thepart in!

Now, the most important time saver: TEST THE PEDAL AFTER EACH CHANGE!!

Let me say that again: TEST THE PEDAL AFTER EACH CHANGE!!

Why test the pedal? That way, if you DID mess up, you know that it has something to do with that lastpart you installed. If you contact me about a problem, be prepared: the first question I’ll ask is “Didyou test the pedal after each change?” If you say no, I won’t be of much help to you!

No need to put the back cover on, just plug it into your guitar and amp and make sure everything is going asit should.

If you don't hear any sound, or it makes a funny sound, then you know something is not right. First jiggle thepedal a little bit to make sure nothing is grounding out against the case (since the cover and circuit board isnow loose). If that doesn't fix it, make sure the orientation of part is correct (as in electrolytic caps, tantalumcaps, diodes, and leds -- see ‘chart’ included with this kit). Double check the solder joints to make sure theyare done properly—use of a magnifying glass makes it a ton easier! Make sure that the component youinstalled doesn't have its legs touching any other component's legs or against the case or anything thatmight cause it to ground out. If your still having problems, simply remove the part and try it again.

99.9% of the time it is an incorrectly soldered joint.

Continue replacing parts on the circuit board, by going down the list. Check the pedal after each componentis installed.

Resistors and capacitors (except electrolytic and tantalum capacitors) do not need to be orientated anycertain way, there is no positive or negative side of them.

When replacing electrolytic and tantalum capacitors, diodes, LED's (which are a diode that give offlight), all need to be orientated correctly.

See the accompanying chart to get a better understanding of how to know if a component will needorientated or not.

When you need to change a capacitor (I call them ‘caps’, so if you see both terms, please don’t getconfused!), its easiest if you bend the legs (also called the leads) like this before you solder it in. This issimply because of the location of the capacitor prohibits you putting it in straight.

For example, this is the easiest way to install a capacitor on the tone pot of a blues driver.

Then, of course, cut the legs off (like you do after each component is installed, and tested).

When changing diodes, make ABSOLUTELY sure you put them in correctly! If you don’t, the pedal will notwork when on. Here is how you would orientate them:

Lastly, you might want to change the LED on/off indicator. Unscrew the screw and pull out the mini circuitboard gently with your needle nose pliers.

Make sure you mark the orientation of the led. I always mark this side, but you can mark either side, itdoesn't matter. What DOES matter is that whichever way the stock led is orientated, the new led must beorientated the same way. If its not, the led simply won't work.

If in doubt, touch your new LED on their solder pads, with the pedal plugged in, and on. If it lights up, yourgood, If it doesn’t, turn the led around.

If you use a 3mm led like I do, you won't have to drill the case, if you use a 5 mm led, you will have to drill.First find a drill bit that is just barely larger than the led.

__________________________________________________________________________

Drill VERY carefully, and slowly. You don't want to go fast and go through quickly and risk hitting somethinginside (yes, I did learn the hard way! :) )

Blow the metal debris out (a can of compressed air helps, but not absolutely necessary).

Test everything once again before you put the cover back on.

Your Done! Your ready to rock!

I hope you've enjoyed this instructional program on how to mod your boss pedal, showing the sd-1overdrive as an example. Email me with any questions and comments Brian@indyguitarist.com orwampcat@yahoo.com !

Thanks!Brian Wampler

http://www.guitartone.net - THE place to make your guitar tone BETTER!

http://www.indyguitarist.com/

http://www.howtoplayguitar.net/ - Guitar lessons, tip, tricks, jam tracks – to make YOU the best guitaristpossible!

See Next Page for Additional Notes

Different types of connections—they will yield differentresults!

Diodes In Series:

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http://www.indyguitarist.com/

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email: Brian@indyguitarist.comorwampcat@yahoo.com

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capacitor codes

third digit meaning

0 multiply by 1

1 multiply by 10

2 multiply by 100

3 multiply by 1,000

4 multiply by 10,000

5 multiply by 100,000

8 divide by 100

9 divide by 10

Large capacitors have their values printed on them in plain terms, such as 100 uF. (We use the letter u as asubstitute for the Greek letter micron, so "100 uF" represents 100 micro-farads.)Small capacitors often use a 3-digit code to indicate their value. This code is similar to the resistor colorcode scheme, except that it uses digits instead of colored stripes. The first two characters are the 1st and2nd significant digits, and the third digit is a multiplier. Values are expressed in pico-farads. Examples:

code meaning

221 220 pF

222 2200 pF

223 22,000 pF = .022 uF

224 220,000 pF = .22 uF

225 2,200,000 pF = 2.2 uF

228 0.22 pF

229 2.2 pF

If there are only 2 digits printed on a small disc capacitor, this is likely to be the value written directly in pico-farads, such as "47" = 47 pF. There is some ambiguity with 3-digit numbers ending in zero; "220" mightmean 22 times 1, or it might mean 220.Letters are used to indicate tolerances. For example, a cap marked 102J has a nominal value of 1000 pFand a +/- 5% tolerance. It can have an actual capacitance as low as 950 or as high as 1050 pF.

letter tolerance

F +/- 1%

G +/- 2%

H +/- 3%

J +/- 5%

K +/- 10%

M +/- 20%

Capacitors sometimes have a letter-number-letter code, such as Z5U or X7R. This code indicates theminimum and maximum temperatures at which the cap is rated to function, and the amount of change incapacitance that will occur across that range of temperatures. As a general rule, you won't need thisinformation unless you are planning to operate your equipment at near-freezing or near-boilingtemperatures.Capacitors marked NPO are designed to have minimal fluctuations of value over a normal range ofoperating temperatures. This high stability is desireable in oscillator circuits, but is generally not necessaryin other capacitor applications.Capacitors sometimes have a maximum voltage rating printed on them also. Generally speaking, tinycapacitors cannot endure high voltages, so if a cap is too small to have space for a voltage rating to beprinted on it, assume that the maximum working voltage is 50 V or less.

Found at: www.alfalima.net