I don't know if this will help, but I have a Viewsonic TV Model N1630W and a Dish DVR 722... I was able to use code 818 in the remote to control the TV. Power, volume, mute, keypad worked... I found lots of codes that turned the TV on and off, but this is the only one that also controlled the volume.
Thank you for contacting ViewSonic Technical Support.Model Number N3250w
I tried the auto find with no luck