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Note:
There are two versions of the membrane switch. The original
membrane switch design has gridlines screened onto the
viewing area, and is used with an LCD that does not have
gridlines.
The current membrane switch design does not have gridlines
screened onto the viewing area. This membrane switch is
designed for use with an LCD which has gridlines screened onto
the viewing area.
Gridlines provide distinct separation between the 6 sections of
the LCD.
if you need to replace an original membrane switch,
you will need to replace the LCD to ensure that gridlines are
visible to the user.
Visually inspect the membrane switch for damage.
If the membrane switch
is punctured or torn, it could possibly altow fluids to enter into the display
PCB and should be replaced.
Testing the Membrane
Equipment Required
Switch,
Ohmmeter
Procedure
1.
Remove the bezei top per the Removing the Bezel Top procedure on
page 22.
2.
Use an ohmmeter to check the resistance between each of the contact
pins and the common pin per Figure 17. In Figure 17, the left-most
contact (pin 1) is the common line, with the other lines being the signals
from the switches. Verify that there is continuity and check for
intermittent failure by applying pressure to the corresponding button for
each of the six (6) contacts for several seconds, monitoring the
ohmmeter for any break in the circuit.
If necessary, refer to the Display
Schematic located at the end of the manual.
If any of the contacts show
signs of an open circuit or intermittent failure, the membrane switch
probably needs to be replaced.
Figure 17
3.
If all contacts pass the continuity check and the problem persists, there
may be a defect on the main PCB.
If available, connect the suspect
membrane switch to another CritiCore Monitor to verify problem.
Removing the Membrane
Equipment Required
Switch
*
No. 1 Phillips screwdriver
«
No. 2 Phillips screwdriver
* o Small standard screwdriver
*
Needle nose pliers
Page 24
Bard CritiCore Monitor Service Manual
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