led not working on sprout

[D4niel423]

Hi all, over the last few months I have spent a lot of time reading thread after thread on this great forum. Well I just finished building the sprout and when I tested it out the effect worked (awesome fuzz) but the led didn't light up and there was a bit of hum which didn't happen with my friends pedals (tested at friends house). So any tips would be great. Also when I went to Jaycar (from Australia) the guy there said that I should be using a 300ohm resistor instead of 4.7k like in the build guide. I'm using the leds from tayda.
Thanks Daniel

[DutchMF]

Hi Daniel, and welcome! If you are talking about the resistor that connects the LED to ground, the value only has an effect on the brightness of the LED, lower=brighter, higher=dimmer. 300R does seem a bit low, might fry your LED. Check out the wiring of your LED, and the orientation, if you have it backwards it won't light up.
The hum could have a number of reasons, easiest to check is run the pedal on a battery, if the hum is gone it's a power issue. Be sure to read the "Rules for getting tech help" sticky, makes it a lot easier for the geniuses here to help you out! Good luck

Paul

[D4niel423]

Thanks for reply. I noticed that another user had a similar problem in which his fuzz pedal made a hum noise due to incorrectly installing a transistor. When building the pedal I had a hard time of correctly orienting the BC109 transitor. Unlike the plastic transistors it is completely round so I tried to use the pin placement to figure it out, i.e. I assumed the two pins next to eachother was the "flat side" on one of the plastic bodied transistor.
In response to you suggesting about running the pedal on a battery I did (made a battery to dc adapter as it's a 1590a build) however the led still didn't light up. The battery is quite old so according to my DMM is only supplying 5 volts, but shouldn't that still be enough to power the led? I do have a basic knowledge of the theory from school but am new to the practical side.
Thanks again
Daniel

[DutchMF]

You might want to post some clear, well lit, in focus pictures of your board and switch wiring, as I'm not sure we're talking about the same things. Regarding the transistor, the only sure way to know if you have the pin-out correct is by checking the manufacturers datasheet, so try to locate those.

Paul

[D4niel423]

I'll post some pictures as soon as I can.
I have done a lot more troubleshooting into the led issue and have concluded the following

• The LED is not faulty as it consistently lights up when I connect a battery to it
• The 3PDT switch wiring is correctly in accordance with the standard wiring diagram
• I checked all soldered connections with the continuity setting on my DMM

My conclusion is that the resistor I am using is in some way faulty. While I understand that this is extremely uncommon, there is no current flowing through it to make the LED light up. I have tried changing the LEDs which seems to work for a short time but then they stop working. I find this very strange. I am using a 300ohm resistor. Any light you could shed on the possibility of a faulty resistor would be great.
Thanks
Daniel

[BraindeadAudio]

I have burned a few resistors out by simply soldering them tot he leads of an LED. It happens occasionally, I personally have found that before soldering my LEDs I always wrap the lead from the resistor around the leg and bend the other leg of the LED around the wire coming off the footswitch. Its only to make sure everything works before I solder it. I have also occsionally had a problem with LED bezels with cheap plastic inserts making the legs of the LED ground out against each other, so I use a dentists pick to seperate them and squeeze some super/gorilla glue inside the LED bezel to keep them seperated. Just a few hints that could hopefully help!

[D4niel423]

That's a really good tip. As far as I can tell the LED hasn't shorted out but I will keep it in mind. Unfortunately my DMM has just ran out of batteries (bad timing huh) so I can't test anything except continuity at the moment. I think I will try you tip about testing it all before soldering the leads though.
Thanks
Daniel

[BraindeadAudio]

The leads on some resistors are so flimsy as soon as they get hot they snap right off. I keep a note of where I get all my parts from and who I get bad/flimsy things from. Just something I do to avoid set backs and headaches such as this.

[BraindeadAudio]

Also, your 300ohm resistor may be why it isnt lighting. Your resistance directly relates to how bright, and if your blowing the LED out or not. the 4$ pack of 200 4.7k resistors you use now, could be the 25-30 cents an LED you save later.

[D4niel423]

I do believe that I have correctly installed the LED and I can get it to light up if I run power from its positive to negative terminals but not when using the dc jack. When the switch is in bypass position the resistor conducts electricity and does its job, but when the switch is in the active position won't allow anything through. I have no idea how this could happen. I have been testing both 4.7k resistors and 300 ohm resistors and the same thing happens with the switch even though I am just using a battery to test from the resistor to the anode. I have never heard of such a thing so any help will be very welcomed
Thanks
Daniel