Peter,

It is possible that the codes don't exist. I compiled and posted the known NEC plasma codes some time ago, and they are complicated by apparently three NEC plasma display variants that respond to somewhat different codes.

If you really want to find other discrete codes, the best way would be to test all codes by generating all 256 codes each for NEC:24 and NEC:24.24 with John Fine's MakeHex found under utilites here at RC.

Keep in mind the normal caution that you could encounter reset commands, service modes, and potentially wipe out factory callibration. Here are the commands that I know of:

NEC:24

OBC or
Fcn EFC
008 053 On / Off
009 057 SVC
010 055 Video
015 058 Display
030 246 sleep
070 166 Contr. +
071 170 Contr. -
072 037 Color +
073 041 Color -
074 039 Brightness. +
075 043 Brightness. -
076 036 Tint +
077 040 Tint +
078 038 Sharpness+
079 042 Sharpness-
088 229 RGB/PC
045 088 Video1:
046 086 Video2:
040 085 Random RGB:

NEC:24.24

028 244 DVD/HD
097 201 RGB/PC1:
098 199 RGB/PC2:
099 203 RGB/PC3:
173 096 Wide / Format / Zoom
176 157 Up Arrow
177 161 Down Arrow
178 159 Left Arrow
179 163 Right Arrow
180 156 Menu
181 160 OK
192 173 Off
196 172 í
197 176 Exit

-Jon