How to Reverse Engineer a Schematic from a Circuit Board

This project is a result of needing to service a domestic electronic item without being able to obtain a circuit diagram.

The process proved to be very long and painstaking, but also very rewarding.  The steps presented here are not exact, and you will no doubt find your own way of working which is more effective in the case of any particular board.  However, I believe the basic procedure is essentially correct for the majority of boards which are too complex to reliably hand trace. Without the need to invent the process, things should progress more quickly.

For simple boards, it is probably better to use pencil and paper to draw the board onto squared paper, replacing components with their symbols, and changing track crossing places to avoid components.

Source: throbscottle