I need the code for apex dt250a converter box

Try 10748 for your apex digital unit. If this doesn't work, you will have to go through the SetNStep procedure below.
StepNSet

• Set the "Mode Switch" to the desired mode such as TV for a Television.
• Press and hold the "Mute" button and the "Select" button until the visible LED blinks twice.
• Enter the code "991" followed by the "device number"
  1. for Televisions
  2. for "AUX 1" devices - VCRs or DVDs
  3. for "AUX 2" devices - Audio
• You can step through the setup codes for this mode by pressing the "Channel Up" key to go forward through the codes or pressing the "Channel Down" key to go back to the previous codes.
• You can try out each code by pressing one or more function keys such as power, volume or digit keys.
• When you've found the setup code that works for your device, press the "Select" key.