d) 2 or 3 #14 or #12 gauge wires from ground plane to ground
bus on Mother board.
e) 2 #18 gauge wire from External Switch pads to power switch
on CP-A or on back panel.
f) 2 wires (#18 or #20 gauge) from switched AC pads to fan (if
fan installed) install insulated tubing over fan terminals.
g) 3 wires from power cord to terminals W, G, and B on PS-C.
'Make sure the power cord wire colors match the label on
the panel .
INSTALLATION OF CP-A PANEL AND CONNECTION TO POWER SUPPLY
Plug the completed CP-A panel into the front 100 pin connector on
the Mother board. Install the eight Allen head screws into the
PEM nuts on the sheet metal front frame. Solder the two #18 gauge
wires from the External Switch pads on the Power Supply assembly to
the power switch pads on the CP-A panel. Provide as much clearance
as possible between the connections on the CP-A board and the sheet
metal front frame. Be careful not to damage the acrylic panels
with the soldering iron.
CHECK OUT OF POWER SUPPLY
Before plugging in circuit boards except the CP-A board,
the unit should be plugged into the AC power supply and
the power supply turned on by depressing the front panel
rocker switch. The voltages at the outputs should then
be measured (any DC volt meter with a full scale voltage
of 20 to 50 volts will do) and the voltages should read
approximately 18 volts on the +18 and -18 volt outputs,
and 10 volts on the +8 volt output. If the voltage does
not come to these values, a check should be made that
the positive and negative terminals of the capacitors are
connected properly and the diodes are mounted properly.
If there is a problem with any of these items a wiring
error has probably been made and the wiring should be re
checked carefully. If the wiring is checked and no error
is found, assistance should be sought from a person know
ledgeable in electronics or from the factory.
When the voltage of the capacitors has been checked out
to be satisfactory, the unit may be turned off. A 10
minute wait will permit the capacitors to discharge.
While there is considerable energy stored in the power
supply filter capacitors when they are fully charged, the
voltage levels are not high enough to present a danger.
Some care should be taken, however, not to discharge the
capacitors by shorting them with a tool or other metallic
object.
IMSAI 8080 System
General Assembly and
Test Instructions
33
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