Keithley 199 Instruction Manual page 137

MAINTENANCE
WARNING
To~prevent a possible shock hazard, disconnect
the line cord and all test leads from the Model
199 before beginning disassembly.
1. Cak cover removal:
A. Remove the two bottom screws that secure the case
cover to the case sides.
NOTE
It is not necessary to remow the feet.
B. Remove the screws that secure the rear bezel, then
remove the bezel.
C. Carefully slide the cover off the unit to the rear.
2. Scaiiner board removal (with option 1992):
A. Pull out the quick-disconne~ti~plugs from the rear.
B. Remove the three screws that secure the scanner
board to the analog board and rear panel.
C. Grasp the board by the edges~ and gently @l it
toward the front of the unit until it clears the rear
and side of the case.
D. Partially pull the board free of the unit to allow ac-
cess to the ribbon cable plug underneath.
E. Unplug the scanner board ribbon cable (Pl), and
remove the scanner board completely from the unit.
3. Digital board removal:
A. Disconnect the trigger signal connector (Pl5) and
display board ribbon cable (P14) from the digital
board.
B. Remove the screw that secures the digital board to
the analog board standoff.
C. Remove then two nuts that secure the IEEE&8 coti-
nectar to the rear panel.
D. Remove the four screws that secure the left grooved
side uanel. then remove the side Danei.
1
E. Pry the digital board free at connector Pl6 (at the end
next to the power transformer) until it comes free of
the connector pins, then remove the board from the
unit.
WARNING
"ihen removing oi installing the digital board,
be careful of the sharp points on the connec-
tor pins.
4. Front panel and display board removal:
A. Disconnect the five wires going from the front panel
input jacks to the analog board.
B. Carefully pry the locking tabs free of the front panel
rails, then remove the front panel.
C. Remove the screws that secure the top and bottom
rails to the right case sides, then remove the rails.
D. Grasp the display board by the edges, and remove
the~board by Fulling it forward until it is clear of the
analog board tab.
5. Analog board removal.
A. Remove the two screws that secure the rear panel to
the case right side. As the screws are removed,
remove case side.
8. Remove the nut that secures the green ground wire
to the rear panel.
~-C. Disconnect the four rear panel input jack wires.
D. Remove the two nuts that secure the AC receptacle
to the rear panel, then remove the rear panel from
the analog board.
WARNING
When reassembling the unit, the green ground
wire must be securely connected to the rear
panel to ensure continued protection against
possible shock haze&.
6-14