Galaxy II Operating Manual 9
5.6 Darthead
The darthead assembly consists of (from front to back):
the spider and segments, a matrix cushion, and the switch
matrix. This assembly is resting on two screws at the bot-
tom and is secured to the door (backboard) by means of
five spider retaining latches.
A single 19 pin ribbon cable on the switch matrix brings
the signals to connector J14 on the main PC board.
A. Darthead Disassembly/Reassembly
To clean or replace parts in the darthead:
1. Remove the four retaining screws and remove the catch
web.
2. Disconnect the switch matrix cable from the main PC
board.
3. Hold the spider and segments against the backboard while
sliding the retaining latches off the spider. Do not remove
the two resting screws at the bottom of the spider.
4. Grasp the switch matrix, matrix cushion, and spider
together as a unit and gently pull the assembly (top first)
off the backboard. Keep the face of the spider and seg-
ments angled downward. Tipping the assembly face up
will allow the segments to fall out.
5. Lay the assembly face down on a flat surface.
NOTE: It is recommended, at this point, that the switch matrix,
matrix cushion, and spider be marked with a permanent mark-
er before disassembly to make proper orientation during
reassembly easier.
6. Lift off the switch matrix, then lift off the matrix cushion,
exposing the segments.
7. Check for dirt, broken tips, or other foreign matter
between the spider, segments, matrix cushion and switch
matrix. Check and remove any broken tips inside the seg-
ments. Remove the segment back cover by gently prying
it up. Snap the cover back in place when finished.
8. Replace any worn or broken segments.
9. There is a small locating hole on the outer edge of the yel-
low spider. It is smaller and closer to the edge than any
other hole. With the spider and segments face down, posi-
tion this hole at approximately 10 o’clock (top and slight-
ly left). The two alignment pins should be near the top and
away from you.
10. Check the matrix cushion for badly worn spots or holes. If
none are found, clean the cushion and set it over the align-
ment pins and back on the spider. There is a small “U”
shaped cutout on the edge of the cushion. Place the cutout
toward the top of the darthead. This cutout will line up
with a similar cutout on the switch matrix in the next step.
11. Clean the switch matrix and place it over the alignment
pins and back on the matrix cushion with the tail at 9
o’clock. Make sure the cutout on the switch matrix lines up
over the one on the matrix cushion. Adjust the matrix
cushion if necessary.
12. Grasp the spider, matrix cushion and switch matrix as a
unit. Install it on the backboard by placing the bottom first
on the resting screws. Gently rock the top backward, align-
ing the pins with the holes in the backboard. Make sure the
matrix ribbon cable goes through the hole in the back-
board. Press it against the backboard until fully seated.
Turn the retaining latches over the spider to secure the
assembly in place.
13. Make sure the ribbon cable is through the backboard and
the top (12 o’clock) double segment is black and aligned
straight up. Remove the assembly and make any adjust-
ments if necessary.
14. If alignment is correct, reinstall the catch web with the four
screws provided and reattach the ribbon cable to the main
PC board. Installation is now complete.
It is important to keep dirt and foreign material out of the
area between the spider and segments as non scoring or
improper scoring can result. On heavily played machines it
is a good practice to disassemble and clean the darthead
regularly. Following this suggestion will prevent service
calls between scheduled visits.
B. Missed Dart Detector
The machine has the ability to detect darts that miss the
darthead and strike the surrounding catch web. Mounted
behind the web is a vibration sensitive piezoelectric switch
circuit board. The wiring harness from this switch is con-
nected to the main PC board at connector P5.
If the Missed Dart Detector detects a hit anywhere on the
catch web face, the machine will record a dart thrown and
no score will be given.
There is a small sensitivity adjustment pot on the detector
assembly. Turning it clockwise will increase the sensitivi-
ty and counter-clockwise will decrease the sensitivity.
This is a single revolution pot, there are no stops when
turning it. One complete revolution brings the setting
back to the same point, adjustments should be made in one
tenth revolution increments.
Figure 9a
Touch Positive Lead
