matching transistors HOW????
 

To all,
I am working with a DC motor that goes forward and reverse. The motor is
controlled by a heat-sinked and fan cooled bank of 5 mj15003 transistors( 5
each forward and reverse). On occasion the motors build up a high amount of
copper on the armatures, from the brushes and this causes one of the 5
transistors to heat up and fail. The manual and the manufacture suggest
matched transistors. What is a matched transistor????? I am guessing that
they are tested and all have similar characteristics. But what
characteristics am I looking for?? especially in a DC motor control.

Anyone have an answer for a semi technically literate person???? (i.e., I
know the hot end of the soldering iron, from the cold end and have the scare
to prove it!!!)

Thanks in advance....

Bob in PHX