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  • #1

    Question for the DIY pedal makers/modders.

    Last night I was going to start the project of modding my BYOC Screamer Clone. I wanted to record some clips with it before modding so I took the pedal off of my board and took it to the studio downstairs. My roommate plugged it into one of his power supplies and the thing would not work. I plugged it back into my board and it still didn't work. This is the first issue I have ever had with it. I took it apart and smelled that nasty burned electronics smell. I went over the pedal with a magnifying glass and couldn't see any issues whatsoever. The 1st thing i did was pop in a new JRC chip and whala that fixed it. Somehow i burned up the chip that was in it.

    Question 1: How sensitive are those chips?
    Question 2: Where do you guys buy your chips?
    Question 3: Could the wrong ploarity on a 9V PS have caused this?


    BTW: Taking the stock pedal and doing asymmetrical clipping via 1 IN914 and 2 IN4001 diodes makes a nice difference. I think I will keep the pedal like this for a while!!!
    I get weak in the knees at the sight of a vintage Fender amp!
    Tags: None
  • #2
    Re: Question for the DIY pedal makers/modders.

    As far as sensitivity and cause I am not sure, but I buy my chips and other stuff at http://www.smallbearelec.com/home.html
    Current Gear: USA Custom Dinky S: Mahogany Body, Pau Ferro Neck & board, DD, Jazz. Schecter C1 E/A: C5, Jazz. Wolfgang Special USA: Air Zone, Air Norton. Ibanez RG7621 7 string. Schecter Stiletto Studio 5 string Bass. Line 6 Vetta 2 with Mesa Recto Cab
    Past Gear : Schecter C1 Blackjack. ESP LTD KH602. Ibanez S 7 string. Ibanez RG7420 7 string. Mesa Rect-o-verb Head. Peavey Classic 50 4x10. Line 6 POD 2.0

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    • #3
      Re: Question for the DIY pedal makers/modders.

      If there is no stuff on the inside to secure anything, your chip will fry if you use the wrong polarity.

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      • #4
        Re: Question for the DIY pedal makers/modders.

        Yup, wrong polarity is usually the culprit when there is no protection against it. Too much heat from soldering irons can do it too. That is why I always socket any circuit with IC chips. I even socket transistors. Makes it a lot easier to swap things when wanted/needed. Those chips are sensitive. Static electricity can potentially fry them.

        Parts Sources:
        Small Bear Electronics
        Mouser
        DigiKey

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        • #5
          Re: Question for the DIY pedal makers/modders.

          I am guessing the BYOC clones don't have the built in protection and the wrong polarity fried it! These pedals do have a socket that solders to the board and from there the chip is placed in the socket. Not enough I guess!
          Last edited by B Bent; 06-13-2006, 11:37 AM.
          I get weak in the knees at the sight of a vintage Fender amp!

          Comment

          • #6
            Re: Question for the DIY pedal makers/modders.

            What you can do is get a diode, a 1n4001 will work, and place it from the power rail to ground. It may require another wire run or something (I don't know what the layout looks like on the board for that one). The line on one end of the diode faces the +9V supply rail. It'll be better than nothing.

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            • #7
              Re: Question for the DIY pedal makers/modders.

              Yep use a diode, then the current only runs one way

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              • #8
                Re: Question for the DIY pedal makers/modders.

                Originally posted by ErikH
                What you can do is get a diode, a 1n4001 will work, and place it from the power rail to ground. It may require another wire run or something (I don't know what the layout looks like on the board for that one). The line on one end of the diode faces the +9V supply rail. It'll be better than nothing.
                Originally posted by Rid
                Yep use a diode, then the current only runs one way
                Heh . . . you guys are talking about two different things. Erik is refering to placing the diode backwards across the power supply pins. Add a fuse in series with it and you have a classic "crowbar" circuit.

                Rid is refering to placing the diode forward biased in series with the positive supply rail, thus preventing reverse polarity. The downside of that is, you also reduce available voltage by about 700mv.

                Usually, a standard 9-volt battery clip will prevent you from hooking up power backwards. Although, if you used external wall-wart power, its easier to mess up.

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                • #9
                  Re: Question for the DIY pedal makers/modders.

                  Originally posted by ArtieToo
                  Heh . . . you guys are talking about two different things. Erik is refering to placing the diode backwards across the power supply pins. Add a fuse in series with it and you have a classic "crowbar" circuit.

                  Rid is refering to placing the diode forward biased in series with the positive supply rail, thus preventing reverse polarity. The downside of that is, you also reduce available voltage by about 700mv.

                  Usually, a standard 9-volt battery clip will prevent you from hooking up power backwards. Although, if you used external wall-wart power, its easier to mess up.
                  The diode will drop the voltage by around .6V. If you look at the Boss PSA adapter, it puts out 9.6V. That extra .6V is to make up for the voltage drop from the reverse protection diode they put in. By putting the diode from the power rail to ground like that, it stops the positive voltage from traveling across the ground plain and frying components that don't like that, such as IC's and electrolytic caps. With the diode in series with the power rail, reverse polarity can potentially still kill some components because there's nothing stopping the positive from not hitting them.

                  If I'm wrong anywhere, please correct me, but from what I've learned in my short DIY venture, that's what I understand it to do.

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                  • #10
                    Re: Question for the DIY pedal makers/modders.

                    If I'm reading you right, thats not quite correct.

                    What rid was describing would be the top pic, and what you're describing would be the bottom:



                    In the top one, you simply block reverse polarity voltage. Since the voltage "drops" across the diode, you lose approx 600 - 700mv. (Depends on the diode.)

                    In the bottom one, the diode "re-routes" the voltage, bypassing the circuit. No voltage drop per se.

                    Both are acceptable forms of circuit protection. It just depends on the circuit. Usually, on the bottom one, you'ld add a fuse so that that blows rather than burning up the diode. Car stereo amps are notorious for using the "burnt-diode" technique. It forces you to take the amp to a tech for an expnsive diode replacement.

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                    • #11
                      Re: Question for the DIY pedal makers/modders.

                      Yup, you're right, Artie. I looked at my notes again. I haven't built anything in months (no time really) so some stuff slips the mind.

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                      • #12
                        Re: Question for the DIY pedal makers/modders.

                        Yeah, I haven't built anything in ages. I really need to take the time to build a couple things. Some of those BYOC pedals look cool. Runoffgroove has some neat looking stuff too.

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                        • #13
                          Re: Question for the DIY pedal makers/modders.

                          I've done a few projects from Runoffgroove. Good stuff. They've even inspired me to come up with a few of my own.

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                          • #14
                            Re: Question for the DIY pedal makers/modders.

                            This thread is a perfect example of why this is my favorite forum on the web!!

                            Great info guys! I am a sponge and taking notes!! thanks to all!!
                            I get weak in the knees at the sight of a vintage Fender amp!

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                            • #15
                              Re: Question for the DIY pedal makers/modders.

                              Glad to be able to help.

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