7.    Depth  reading  does not   change   (See   Sect. 7) 8. Random depth readings with no relation    to    the    actual depth 9. Continuous very shallow   readings,   such as .7 or .8 on a No. 550, or  1  or  2  on  a  No.    530 or No. 540 10.    On  the  No.  550,  at very   shallow   depths   of less   than   four   ft.,   the depth reading is different    on    the    2.0'- 99.9' range, than on the 4'-499' deep range 11.    Alarm  WILL  sound, if... a. Move   DISPLAY switch    from    "Alarm Set" to "Depth". a.   Electrical interference from Ignition     system     on engine or generator; b.   Electrical interference from charging system; c.   Mechanical   vibration of transducer, d.   Incorrect    transducer mounting, causing air    bubbles    to    flow across    the    face    of the transducer. a.   Air    bubbles    across transducer; b.   Boat in shallower water than the depthfinder is designed to read. a.   Depth too shallow for the deep (4'-499') range-use    the    2.0'- 99.9' "tenths-of-a- toot range. a.   Water     is     shallower than   Shallow   Alarm setting b.   Water is deeper than Deep Alarm setting; c.   Deep    Alarm    is    ON and    "No    Echo"    is received (increase sensitivity); d.   Both  alarms  are  ON and Shallow Alarm is adjusted  deeper  than the    Deep    Alarm    or vice-versa; 12.    Alarm  MAY  sound, if... 13.      Remote   No.   540 reads    slightly    different depth   than   the   master unit 14.      Remote   No.   540 reads    much    differently from the master unit e.   Both   alarms   are   on and  DISPLAY  switch is  up  to  ALARM  SET (alarms  must  be  set separately). a.   The    unit    is    turned OFF,   ON,   or   power is    momentarily    lost due    to    a    poor,    or intermittent power connection; b.   There  is  severe  sub- surface     interference present when the Shallow  Alarm  is  ON (reduce the sensitivity) c.   There is severe electrical interference   present: (See page 15 "Interference") d.   There is a momentary voltage drop    due    to    some other electrical accessory on the boat  cycling  on-such as    bilge    blower    or pump. a.   A     normal     variation due to accuracy tolerances. a.   Sensitivity  control  on either the No. 540, or the    master    unit,    is incorrectly adjusted; b.   Operation outside the    rated    depth    of the No.  540; c.   Check   both   the   No. 540   and   the   master in a known-depth area,     to     determine which    unit    requires recalibration. SPECIAL TIPS ON 540 REMOTE 22