pentium75

I was wondering if anyone has any ideas on how to shrink the picture thats displayed on a crt. Ive played with the idea of messing with the yolk (yoke?) voltage but i dont want to kill this monitor with a mistake. Im looking to get the size of the picture somewhere around 60% smaller than the crt size for a project. Note that monitors controls cannot shrink the picture to the size i would like. thanks for any help. PWD