The mystery of the dead LED

Hi all,

Need a little help if anyone can give it. I just built an MXR Distortion Plus clone, using the General Guitar Gadgets PCB. The components were a combo of spare parts and stuff I got from Pedal Parts Plus. Among the PPP items were a 5mm yellow LED and a TPDT switch. I got the pedal all wired up and it works fine, except the LED doesn't light up. I figured I fried it with my less-than-pro soldering skills, so I bought another one at the Shack, verified I had it oriented right, and soldered it in. Still no light. I double-checked everything. The LED part of the circuit is dead simple, and I have it wired correctly.

Do I have a bad switch? What else could account for this?

Check the resistance from the positive terminal of your power supply (i.e. battery or jack) to the positive terminal of the LED. If the resistance is significantly higher than the resistor in series with the LED, you might have a bad connection. If the resistance is infinite, you have a discontinuity. This could be the switch. To check that, set your multimeter to resistance and measure across the pole for your LED circuit, the resistance should be very close to 0 Ohms when the circuit is engaged and infinite (or very high) when the circuit is disengaged.

It could also be a ground. How about some pictures?

Many thanks! I'll get the multimeter and camera out as soon as I can. If I can avoid wiring in another switch, I'd like to.

I may try RAT bypass on future projects.

Many thanks! I'll get the multimeter and camera out as soon as I can. If I can avoid wiring in another switch, I'd like to.

I may try RAT bypass on future projects.

Does the LED work outside of the circuit? IE with a9v battery and a current limiting resitor?

rule out a duff LED before you redo the whole switch.

Try another LED also.

OK, multimeter is telling me I have a cold solder joint at the led resistor. Tomorrow I should have time to fire up the soldering iron and try to remedy that.

111005