HELP: Changing stock LEDs to Brighter LEDs

Discussion in 'Effects, Pedals, Strings & Things' started by balakubak33, Apr 21, 2008.

  1. balakubak33

    balakubak33 Member

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    Hi TGP peeps!
    I really like bright LEDs on my pedals. And on some pedals I can't trace the PCB which resistor needs to be changed to make it more brighter. ;)

    I was advised on the Boss DS-1 it's R35, 4.7K down to 1K, same with SD-1 it's R15..

    Guys do you happen to know which resistor I'd change for BOSS CE-2, Ibanez TS9, BOSS TR-2, MXR Phase 90?

    Thanks!!!
    :bow
    Kevin
     
  2. whoismarykelly

    whoismarykelly Oh look! This is a thing I can change!

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    In all of those cases you could probably change to an actual 'superbright' led which will be capable of more light than the diffused ones in those pedals.
     
  3. amp_surgeon

    amp_surgeon Member

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    Be warned: This will increase current from a battery significantly. You should only do this if you're running on an external power supply, or you don't mind swapping batteries often.

    Boss CE-2: R51, currently 3.9K

    Ibanez TS9: Don't know the ref. designator, but it looks like a 3.6K. It's connected to the cathode of a 3V zener diode on one end, and the cathode of the LED on the other.

    Boss TR-2: R17, currently 1.2K

    MXR Phase 90: Can't find a schematic other than R.G. Keen's, which isn't complete.
     
  4. balakubak33

    balakubak33 Member

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    Thank you! :bow
     
  5. balakubak33

    balakubak33 Member

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    yes it's necessary to make it brighter. :D
     
  6. amp_surgeon

    amp_surgeon Member

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    There are two ways to make an LED of a given color brighter. Focus the light more tightly, or increase the current going through it.

    Most conventional LED's have a diffusing lens which makes the light visible across a wide angle. The amount of visible light is typically around 1000 millicandles (mcd). You can increase the power of this light over ten times without increasing the current just by using an LED with a tightly focused lens. Unfortunately, you won't be able to see the light unless you're looking dead center down the middle of it. Most people don't stand directly over their pedal board looking straight down at their pedals.

    The diffused LED's used in most pedals can usually take a lot more current than they are getting. The designers intentionally reduce the amount of current by using larger resistors in series with them. This is to cut down on the battery drain. In some circuits, like a simple analog fuzz, the LED may be drawing two or three times as much current as the actual fuzz circuit. If you're going to run the pedal on a power adapter then current drain isn't as much of a concern, and you can make the LED brighter by putting a smaller resistor in.

    You don't want to go too far with this, though. The sudden current draw when the LED turns on can cause a momentary sag in the power supply voltage. This can cause a "thump" in the amp when you switch the effect on or off.
     
  7. balakubak33

    balakubak33 Member

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    Really?!! whew I'm not aware of that.. Thanks so much for the help doc
    :bow

    kevin
     
  8. nitehawk55

    nitehawk55 Member

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    Take your sunglasses off :crazyguy
     
  9. Mincer

    Mincer Member

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    I wonder if this is why the Monte Allums opto+ mod for the Boss CS3 pops when you switch it off (I don't notice it popping when I turn it on). The mod contains a super-bright LED.
     
  10. amp_surgeon

    amp_surgeon Member

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    An easy way to find out is to unsolder one leg of the LED. If it doesn't pop anymore then consider putting a bigger resistor in series with it. The math isn't the same as for a red LED because white LED's have a higher forward voltage drop.

    If you want to find out just how far you can go then hang a 330 ohm resistor on the wiper of a 10K pot, and temporarily sub the LED series resistor with this. Turn the pot to dim the LED while switching the pedal on and off. Stop when it doesn't pop anymore, and measure the resistance with an ohmmeter. Use the next highest "off the shelf" resistor value.
     
  11. Flying Panda

    Flying Panda Member

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    Great information here...amazing, really. A couple of weeks ago I finally got tired of the "barely there" red LED on my AD-9, so I went to RatShack and got a white LED that was in the middle range mcd-wise of their selection, then went home, de-soldered the old red one and put in the white one. Tested it before I soldered it in and it worked, so I went ahead and soldered. Now I can see when the thing is on, it looks great...and....it sounds exactly the same. I guess sometimes dumb guys get lucky.;)
     
  12. balakubak33

    balakubak33 Member

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    Doc,

    I tried changing the resistor value on my TS9, from 3.6K I changed it to 1K. It worked just fine but I was tempted to make it as bright on my DS1 ( I drilled a bigger hole to accomodate a 5mm LED on my DS-1), tried a 750K resistor but did not work this time. I tested the LED to check if it's fried and it lit on the battery but did not work with the Godlyke PA9. The effect works just fine but does not have LED right now. Troubleshoot time!

    Kill me for being stupid. Thanks for your help!:bow
     
  13. balakubak33

    balakubak33 Member

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    Doc,

    I tried changing the resistor value on my TS9, from 3.6K I changed it to 1K. It worked just fine but I was tempted to make it as bright on my DS1 ( I drilled a bigger hole to accomodate a 5mm LED on my DS-1), tried a 750K resistor but did not work this time. I tested the LED to check if it's fried and it lit on the battery but did not work with the Godlyke PA9. The effect works just fine but does not have LED right now.


    [​IMG]

    DS-1 modified LED
    [​IMG]

    Changed 3.6K resistor to 1K.
    [​IMG]

    LED worked fine direct on the battery..
    [​IMG]

    But did not work on the PSU..
    [​IMG]

    Kill me for being stupid. Thanks for all your help!:bow
     
  14. AL30

    AL30 Member

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    You can get a super bright LED as opposed to a regular LED but, as amp_surgeon has already stated, you'll be pulling a lot more current and you'll drain your batter much faster. Unless you need it or are using a power supply I wouldn't recommend it.

    AL
     
  15. amp_surgeon

    amp_surgeon Member

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    The LED and resistor are in the collector circuit of a 2SC1815 transistor. This transistor is switched on by the flip-flop circuit that toggles the effect on and off. There's also a 3V zener diode in series with that collector. Assuming the pedal itself still works ok, my assumption would be that you fried either the zener diode or the transistor by pulling too much current through them.

    Trace the circuit path, starting on the other side of the resistor, and identify the zener and transistor I'm talking about. Then, use a multimeter and measure the voltage across them. First, measure the voltage across the zener. Second, measure the voltage from the emitter to the collector of the transistor. Whichever one is dropping 9V is probably blown.

    Once you've identified the bad part, be sure to up the value of that resistor before replacing it. Otherwise, you'll just blow the new part as well. In the event that the transistor is blown, you should be able to use an NTE85 in place of the 2SC1815. Looking at the flat side of the package, the pins should be: emitter, collector, base.

    EDIT: Come to think of it, the zener won't go into conduction if the transistor were blown, so the transistor isn't going to be dropping any voltage. A better test would be to remove the components and check them with an ohmmeter. The zener should read high resistance with the probes in one polarity, and much lower resistance when you swap the probes. The transistor should be checked like two diodes - one from collector to base, and one from emitter to base. If either of these measure infinite ohms in both directions then it's probably fried.
     
  16. balakubak33

    balakubak33 Member

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    Ok I'll try it later. Thanks for your help! :bow
     

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