schematics - Adding diodes to easy driver stepper motor driver

I had an easy motor driver damaged by removing the motor while the drive was energized. I sent an email to Brian Shmalz to see if there was anything that could be done to protect the board in these cases. He replied with the following:

You can add eight diodes to the four motor lines (one diode to M+ and one to GND for each of the four lines) to help protect the driver in case a user removes the motor while under power.

and

You'll want Schottkey diodes with a nice low forward voltage - like 400mV or so at 1.5A or so.

I ordered some of the diodes he recommended however I am still learning when it comes to electronics like this and I don't really understand what he is advising to do.

The board has 4 motor pins in a set of A/B pairs. I don't understand where the 8 diodes should be placed in relation to these pins, or which orientation the + and - sides of the diodes should be in. Schematics and diagrams can be found here http://www.schmalzhaus.com/EasyDriver/

How should this be wired to accomplish what Mr. Schmalz has suggested?

Answer

The diodes are meant for absorbing voltage spikes above M+ and below GND. They have to have low voltage drop to start conducting sooner then the built-in diodes. As the message says, they have to be connected between output and power rails, like this (ignore the depicted buffer):

_{(source: radio-electronics.com)}

Edit: The diodes should be wired like this: