Main Board Mounting - DCS 090 Series Reference Manual

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Main Board Mounting

The preferred mounting for the main board is shown in
Figure 5. The board is mounted on standard 3/8 inch self-
clinching studs (PEM SOS-12-440 or equivalent) pressed into
holes drilled through the end product's front panel. Using self-
clinching standoffs is preferred because the thickness of the
front panel does not affect the position of the switch shaft
relative to the front surface of the panel. The length tolerance of
the stand offs should be ± .006" or better.
Proper standoff installation is critical. Insufficient standoff
protrusion may cause the button shafts to interfere with the
overlay at worst case tolerance conditions. Excessive
protrusion makes the button difficult or impossible to actuate.
Embossing a .030" inch raised 'button' into the overlay will
minimize tolerancing problems.
Maximum required switch shaft travel is .015 inches. At the
worst case tolerance condition of maximum stroke, shortest
shaft length and longest standoff length, the front of the switch
shaft must be depressed .027" below the front surface of the
panel.
In applications where other mounting schemes will be used,
some important tolerances to keep in mind are shown the table
below.
Dimension
Switch shaft length (from front surface of ECB)
Switch actuation travel
Thickness of plating at display board mounting holes
Clearance and Ventilation
All main board components except the display and buttons are on the side facing away from the
front panel. Clearance of at least 1 inch (2.54 cm) must be provided behind the main board to
ensure that there is no mechanical interference with components on the board. There must be
free air movement within the clearance volume; packing the volume immediately behind the
board with loose-fill insulation or the like may lead to localized over-heating on the main board
and is to be avoided.
Thermal Issues
The power supply on the main board dissipates so little heat that self-heating should not be an
issue if the 1 inch back side clearance is maintained. The main board should be located so that it
is not heated to over 50 degrees Celsius by energy dissipated by other heat sources.
2/21/05
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090 Series Reference Manual
Table 7: Important Front Panel Mounting Dimensions
Digital Control Systems
Figure 5: Main ECB Front Panel
Mounting
Value in Inches
.374 ± .006
.010 ± .005
.004 ± .001
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