New guest and a noob question!

[artbarsnstripes]

Hello,
I'm David and i'm new on this forum. I've seen a few posts that are regarding to the MXR Dyna-Comp based on the 70's model. I have myself the '76 Reissue and i'd like to add an LED using only a DPDT switch WITHOUT true bypass, just the intentional hard bypass it was designed as. I've seen others on this forum post about this question, but never getting the right answer or no answer at all. HELP! where should i wire the lead's for the LED without shorting the board?
Thanks

[Mark Hammer]

There will be a pad where the RED wire from the power supply connects to the board.  You will solder a current-limiting resistor in the vicinity of 2.2k to 15k (depending on the brightness of the LED) to avoid frying the LED.

The free end of that resistor will go to the LED anode, and the LED cathode will go to the switch.  More specifically it will go to the side lug of the switch that is on the same side you take the feed from the circuit board.

The "common" of the switch (which would be the middle lug for each set of contacts) will ground the LED cathode.  This means that when you hit the switch and the effect is connected to the output jack, the LED will be connected to ground via the other set of contacts and current will flow through it.

I may be remembering it wrong but usually the longer of the two leads on a new LED is the cathode.  The difference in length will be modest but still visible.  If in doubt, keep a nearly-dead 9v battery on hand and straddle the leads of the LED across the battery terminals to identify which goes to pos and which to ground.  Just let it contact the terminals long enough to determine if it lights or doesn't.  And make sure that battery provides as little tongue-tickle as possible since you won't be using any sort of current limiting resistor at that point.

And welcome on board.  It's a sick sick sick bunch here, some of us for well over a decade.  You,re in good hands.

[artbarsnstripes]

hahaha thanks Mark. This is my story on the situation. I already had installed a LED with hot (red) leading from the 9v supply into a resistor into the LED + then the LED - to the common on the DPDT switch where when the switch turns on the effects, that ground goes back to the 9v supply on negative (black). I'm using a dc brick which cuts out if there's a short so there will be no harm done if i did it wrong, but it's shorting out.