As of Dec 2018 firmware update, the use of the Combination Keys to enable/disable Special Modes will be managed by the Combination Key and Combination Key PW options in the DEBUG Menu*.  

This feature was implemented to prevent inadvertent Locking/Unlocking of the Special Lock Modes.

To enable the feature follow the steps below

1. Using the Remote Control, press INPUT 9 9 1. This will open the DEBUG MENU.

2. Select Other Setting

*Menu options may vary based on model

3. Set the Combination Key option to ON to enable the use of the Special Mode Key combinations

4. Select Combination Key PW  to set a 4-digit password code. Default is 0000.  This code will be required when using the Combination Keys to lock and unlock any of the Special Modes.

*Menu options may vary based on model

5. Select Back

6. Select Exit 

Below is a listing of the button combination to Lock/Unlock the following Special Modes

For IFP50 Gen1/Gen2/Gen3 Series

For IFP52-1C Series

For IFP52-1A Series

*When accessing the DEBUG Menu only make changes as instructed by ViewSonic Support.