Keithley 2700, Service Manual

Page: 103 / 174

Disassembly 5-5
3. Disconnect the front input terminals.
You must disconnect these input terminal connections:
• INPUT HI and LO
• SENSE HI and LO
• AMPS
Remove all the connections except the front AMPS connection by pulling the wires off
the pin connectors. To remove the front panel AMPS input wire (white), first remove
the AMPS fuse holder, then use needle-nose pliers to grasp the AMPS wire near the
fuse housing. Push the wire forward and down to snap the spring out of the fuse hous-
ing. Carefully pull the spring and contact tip out of the housing.
4. Unplug cables:
• Unplug the display board ribbon cable from connector J1014.
• Unplug the transformer cables from connectors J1002 and J1003.
• Unplug scanner slots ribbon cable from connector J1012.
• Unplug analog backplane connections J1008 and J1010.
5. Remove the fastening screws that secure the motherboard to the chassis. One of these
screws is located along the left side of the unit towards the middle, and it also secures
U144. One screw is located at the right center of the chassis near the front/rear switch,
S101, and another screw is behind the AC shield.
During re-assembly, replace the board, and start the IEEE-488, RS-232, and Digital I/O
connector nuts and the mounting screw. Tighten all the fasteners once they are all in
place and the board is correctly aligned.
6. Remove the motherboard, which is held in place by edge guides on one side, by sliding
it forward until the board edges clear the guides. Carefully pull the motherboard from
the chassis.
Card cage removal
After the motherboard has been removed, the card cage that holds plug-in modules can be
removed simply by removing the screws that attach the card cage to the case bottom and
removing it.