Vld Replacement Procedure; Vld Removal Instructions; Vld Installation Instructions - Metrologic MS6520 Service Manual

4.4 VLD Replacement Procedure

4.4.1 VLD Removal Instructions:

4.4.1.1 Open the case to gain access inside the unit.
(Follow Steps 4.1)
4.4.1.2 Carefully remove the decode board from the
unit. (Follow Steps 4.2)
4.4.1.3 Remove the damaged VLD by unscrewing the
two screws shown in the figure to the right.
4.4.1.4 Remove the collector mirror.
4.4.1.5 Remove the SBT resistor from the Signal
Processor board.

4.4.2 VLD Installation Instructions:

4.4.2.1 Install the plastic VLD bracket with the screws
provided with the VLD kit.(for A to C 0232
Revisions)
4.4.2.2 Place a target pin in the collector hole.
4.4.2.3 Using a power up box, power up the replacement
laser.
4.4.2.4 Place the laser in the VLD bracket and place the
beam onto the center of the target pin.
4.4.2.5 Glue in place using Loctite 406 followed by
Loctite 712.
4.4.2.6 When completed determine the VLD SBT and
solder it in. Power should be between 0.780 and
0.820mw out of the VLD.
4.4.2.7 Make sure all the optical areas are clean.
4.4.2.8 Connect SP and motor cables to the power box.
Place optic bench assembly into alignment
fixture and lock in place by pushing locking lever
forward.
4.4.2.9 Turn power on. Motor will spin and VLD will
turn on.
4.4.2.10 Slide the high-density and red pattern windows
all the way to the right to reveal the top window
with the reflective tape.
4.4.2.11 Place target with signal return pattern over
photocell can.
4.4.2.12 Adjust return signal to the center of the target by
manipulating the collector bracket. Do not touch
the coated, curved part of the collector. Beam
must fit into the square on the target.
4.4.2.13 Place cluster target onto mirror #2.
4.4.2.14 Feed joystick through hole in collector mirror
from the front so that the angle of the mirror is
pointing down, and joystick tab is at bottom. Pull
joystick back as far as possible without touching
the collector.
4.4.2.15 Adjust joystick assembly so that the raster lines
are between the target lines on the cluster target.
Make sure the joystick tab remains at the bottom.
4.4.2.16 Make sure the beam fits into the square of the can
target, remove the can target.
4.4.2.17 Your image should now be centered in the
photocell. Using your pliers, gently pull on the
left and right of the collector bracket. The image
in your photocell should look like a circle with
wings on each side. Make sure your "wings"
don't protrude from your photocell.
4.4.2.18 Slide the metal plate with the high-density lines
into place.
4.4.2.19 Attach socket test probe to test pin #1 on the
signal processor
oscilloscope, signal should still be between 2.0v-
3.0v.
4.4.2.20 Slide the red pattern window into place and
verify that the pattern has a closed diamond.
4.4.2.21 Next slide the red pattern window back and forth
making sure that the unit can read the code
located on the left edge of the red pattern
window.
4.4.2.22 Put drop of LOCTITE 406 on joystick where it
comes out the back of the collector. Put drop of
accelerator 712 on same spot as 406.
4.4.2.23 Cut the part of the joystick that protrudes from
the back of the collector as flush as possible.
4.4.2.24 Follow Steps 4.3.2 for decode board install.
4.4.2.25 Follow Steps 4.1.2 for case assembly.
4-7
FIGURE 4.4-1
board. Check signal