TM  1-1520-240-10 3-3-8            CONTROLS/ INDICATOR FUNCTION SPH/VAR (Left Display) Spheroid code of desig- nation set on DEST DISP thumbwheel. (Right Display) Magnetic variation (in de- grees and tenths of de- grees) of destination set on DEST DISP thumb- wheel. MAL Indicator Lamp Lights when set malfunc- tions. In case of an inter- mittent malfunction, sys- tem may operate correct- ly, but must be cycled to OFF and then to on to put MAL light off. MEM Indicator Lamp Lights when radar portion of set is not tracking. May occur over smooth water. DIM Control Controls light intensity of display characters. Left, Right, and Center Display Lamp Alphanumeric and nu- meric characters that dis- play data as determined by setting of DISPLAY switch, mode switch, and keyboard. Target Storage Indicator    Displays destination number (memory loca- tion) in which present position will be stored when TGT STR pushbut- ton is pressed. TGT STR Pushbutton Stores present position data when pressed. KYBD Pushbutton Used in conjunction with keyboard to allow data entry. KYBD pushbutton is always lighted when system is on. DEST DISP Thumbwheel Switch Destination display thumbwheel switch is used along with DEST/ TGT and SPH/VAR posi- tions of DISPLAY switch to select destinations whose coordinates or magnetic variation to be displayed or entered. Destinations are 0 through 9, P (present position) and H (home). CONTROLS/ INDICATOR FUNCTION Keyboard Used to enter data into system. Keys set up data on display. All resulting actions are initiated upon release of the key. FLY-TO-DEST Thumb- wheel Switch Selects destination to which steering informa- tion is desired. Destina- tions are 0 through 9, P (present position) and H (home). ENT Key Enters data set up on keyboard into memory when pressed. CLR Key Clears last entered char- acter when pressed once. Clears entire dis- play panel under key- board control when pressed twice. 3-3-13.  Display and Keyboard Operation. In LAT/LONG coordinates, the two fields of control are the left and right displays. In UTM coordinates, the first field of control is the center display and the second field is the combination of the left and right displays. When pressing the KYBD pushbutton, one or other of the fields described above is under control. If it is not desired to change the information in the field under control, the pilot can  advance  to  the  next  field  of  the  display  panel  by pressing the KYBD pushbutton again. 3-3-14.  Data Entry To enter a number, press the corresponding key. To enter a letter, first press the key corresponding to the desired letter.  Then  press  a  key  in  the  LEFT,  MID,  or  RIGHT column corresponding to the position of the letter on the pushbutton. Example: To enter an L, first press L, then either 3, 6, or 9 in the RIGHT column. The computer program is de- signed to reject unacceptable data (for example, a UTM area of WI does not exists, and will be rejected). If the operator attempts to insert unacceptable data, the dis- play will be blank after ENT is pressed. 3-3-15.  Starting Procedure. a.  MODE selector — LAMP TEST. All lights and lamp segments should be lit. (1) Left, right, center and target storage indica- tor — Lit (fig. 3-3-5). All other lights should be on. (2) Turn DIM control fully clockwise, then fully counterclockwise, and return to full clockwise; all seg- ments of the display should alternately glow brightly, go off, and then glow brightly.