Motherboard Assembly - NorthStar HORIZON Manual

MOTHERBOARD ASSEMBLY
The power supply should be assembled and tested prior to
motherboard assembly. Assembly of the motherboard is performed
in stages. This section describes the assembly of the basic
configuration of the motherboard, including edge connectors,
standard serial I/O interface. interrupts. and real-time clock.
Assembly of other motherboard features will be described in
subsequent sections.
MI. Check to be sure you have all the parts on the Motherboard
Parts List.
Note: The component side of the motherboard is the side with
the layout legend. The front of the motherboard is the end
with the twelve 100-pin edge connector positions.
~j2. Using an ohmmeter. check for open circui ts between the pair
of solder pads for each of the following ten capacitor
locations:- Cl,
C2; C3, C4, C5, C6. C7,
C8,
C9,
and C10.
I f
any shorts ,Ire found. locate and correct the problem or else
return the motherboard for replacement.
M3. Insert and 30lder the 28-pin IC socket at location 3A.
following ti,e instructions given in the Assembly Information
section.
M4. Insert and 301der the three 20-pin IC sockets at locations
SA, 6A, and 7A.
MS. Insert and solder the nine 16-pin IC sockets at locations
lA, 2D. 3D, 6D. 7D, 8B, 9B, 9D, and 10B.
M6. Insert and solder the fourteen 14-pin IC sockets at
locations 2A. 2B. 3B,
3C,
5B, 5[, 5D, 6B.
6C.
7B. 7C, 8D,
10A. and 100. NOTE: If the parallel I/O interface option or
second serial interface option are to be assembled at this
time, then install the sockets for these options now, as
described in steps Ul and Tl.
M7. Install the 100-pin edge connectors as follows: solder the
end and center pins of each connector first. then seat the
connectors as you did for the IC sockets. All connectors
that you plan to eventually use should be installed now to
avoid removing the motherboard later. One connector should
be installed in location P9 on the motherboard for the disk
controller board. Separate the connectors you install as
much as possible to facilitate PC board access. The
standard HCRIZON configuration has connectors at locations
PI, P5, and P9.
Note: Bus lines 61 and 70 are connected to the ground plane
on the motrerboard to reduce bus noise. If you intend to
North Star HORIZON Computer
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