SWTPC MP-B2 Assembly Instructions Manual

The MP-B2 Mother Board is a 9 " x 14" double sided plated thru hole board onto which all of the various
processor boards are plugged. Provisions have been made for one processor board, up to four memory
boards plus two unused slots. This gives the user the ability to handle up to 32K words of memory.
The mother board also provides the line buffering and address decoding for up to eight interface
boards. Although one of the eight must be the serial control interface, the other seven may be any com-
bination of serial (MP-S) and parallel (MP-L) interfaces the user may choose to have. For those
demanding even more interfaces the 50-line processor bus may be paralleled onto another MP-B2
Mother Board with power supply expanding the interfacing to one serial control interface, plus any
combination of up to fifteen serial (MP-S) and parallel (MP-L) interfaces. Doing this requires a minor
modification to the second mother board.
When the SWTPC 6800 Computer System is being assembled, work on only one board at a time.
Each of the system's boards and their associated parts must not be intermixed to avoid confusion
during assembly.
NOTE: Since all of the holes on the PC board have been plated thru, it is only necessary to solder the
components from the bottom side of the board. The plating provides the electrical connection from the
"BOTTOM" to the "TOP" foil of each hole. Unless otherwise noted it is important that none of the con-
nections be soldered until all of the components of each group have been installed on the board. This
makes it much easier to interchange components if a mistake is made during assembly. Be sure to use
a low wattage iron (not a gun) with a small tip. Do not use acid core solder or any type of paste flux. We
will not guarantee or repair any kit on which either product has been used. Use only the solder supplied
with the kit or a 60/40 alloy resin core equivalent. Remember all of the connections are soldered on the
bottom side of the board only. The plated-thru holes provide the electrical connection to the top foil.
( ) Before installing any parts on the circuit board, check both sides of the board over carefully for
incomplete etching and foil "bridges" or "breaks". It is unlikely that you will find any but should
there be one, especially on the "TOP" side of the board, it will be very hard to locate and correct
after all of the components have been installed on the board.
( ) Attach all of the resistors to the board. As with all other components unless noted, use the parts
list and component layout drawing to locate each part and install from the "TOP" side of the board
bending the leads along the "BOTTOM" side of the board and trimming so that 1/16" to 1/8" of
wire remains. Solder.
( ) Install all of the capacitors on the board. Solder.
( ) Install each of the 59, 10-pin Molex male connectors oriented so the shorter pinned side fits into
the holes provided on the mother board. These connectors must be inserted from the "TOP" side
of the board and must be pressed down firmly against the board. Make sure the body of the
connector seats firmly against the circuit board and that each pin extends completely into the
holes on the circuit board. Not being careful here will cause the plug-on boards to be less rigid.
Do not solder the pins adjacent the dotted lines shown in the component layout drawing. It is
suggested that you solder only the two end pins of each of the fifty-nine connectors until all have
been installed; at which time, if everything looks straight and rigid, you should solder the as yet
unsoldered pins still excluding the ones adjacent the dotted lines on the component layout
drawing.
Assembly Instructions MP-B2 Mother Board

PC Board Assembly

Scanned and edited by Michael Holley June 3, 2002
Southwest Technical Products Corporation Document Circa 1978

Introduction

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