Before we go through the mod, let me say something about safety
This project and modification are designed only to be used with the standard 2.1mm ”Boss Style” switching DC input socket that takes a 9v, centre negative DC power adaptor.
Power from the mains AC power supply (the electricity from the plug in the wall) WILL, AND WANTS, TO KILL YOU. Never mess with anything that plugs into a wall socket unless you are 100% confident with the power adaptor, that you know what you are doing, and the circuit you are working on. Absolutely NEVER mess with a device WHEN IT’S PLUGGED INTO the wall. Please be careful, and always put your and others’ safety first.
Now… let’s take a look at the layout of the 2.1mm DC input socket:
Lug 2 – Power (From battery)
Lug 3 – Power (To board)
BE VERY CAREFUL- Check, double check, and triple check your soldering and the pinout of the socket before connecting a power adaptor, or you risk frying your board.
When running on battery, lugs 2 & 3 are connected. When a power adaptor jack is plugged in, the connection between the lugs is broken, saving the battery, and power is only drawn from the adaptor via lug 3.
So here is how the mod went:
1. I opened up the Russian Big Muff:
N.B. if there wasn’t already a wire soldered to the board (from the old battery snap), I would have had to add one from lug 1 to a ground point on the board).