LASER PROBLEM-2
 
 Hopeful, if any of the components mentioned below
 simply got shaken loose. If they're defective...
 well.
 
 --------------------QUOTING-----------------------
 HOROZONTAL BLACK LINES ARE PLACED RANDOMLY
 THROUGH THE PRINT:
 
 Black areas are the result of light striking the
 drum.
 
 A defective or improperly seated beam detector
 could send false scan timing signals to the main
 logic.
 
 The laser would make its scan line while main
 logic waits to send its data, as shown in the
 illustration.
 
 At the beginning of each scan cycle, the laser
 beam strikes a detector. The detector carries
 laser light thru an optical fiber to a circuit
 that converts light into an electronic logic
 signal compatible with main logic.
 
 Main logic interprets this Beam Detect signal and
 knows that the scanner mirror is properly aligned
 to begin a new scan.
 
 Main logic then modulates the laser beam on and off
 corresponding to the presence or absence of dots in
 the scan line.
 
 POSITIONING AND ALIGNMENT ARE CRITICAL.
 
 If the beam detector is misaligned or loose, the
 printer's motor vibrations may cause the detector
 to occaisionally miss the beam.
 
 Main logic responds by activating the logic full
 time in an effort to synchonize itself again.
 Reseat or replace the beam detector and optical
 fiber.
 
 A loose or misaligned scanning mirror can also
 cause this type of problem. Vibrations in the
 mirror may occaisionally deflect the beam around
 the detector. Realign or replace the scanning
 assembly.
 -----------------END-QUOTE-----------------------
 
 
----------ILLUSTRATION
 
------------
LASER-DIODE--------------------> /\
-------------                    \/ MIRROR
  |                            /
  |                           /
--------                    /
LASER-                _________
DRIVER-                  BEAM
CIRCUIT               DETECTOR
----------            ----------
  |                   |
  |                   |    |=========================|
  |      optical      |    |======DRUM===============|
  |      cable------->|    |=========================|
  |                   |
  |                   |
  |                   |
  |             -----------------
  |             LIGHT-TO-VOLTAGE
  |             SIGNAL-CONVERTER
  |             -----------------
  |                   |
  |                   | |--------------------------|
  |                   | |                          |
  |                   |-|-----BEAM-DETECT-SIGNAL   |
  |                     |                          |
  |                     |                          |
  |                     |      MAIN-LOGIC          |
  |                     |                          |
  |                     |                          |
  |---------------------|--LASER-CONTROL-SIGNAL    |
                        |                          |
                        |--------------------------|
 
 

--- Maximus/2 3.01