Motherboard Removal; Card Cage Removal - Keithley 2701 Service Manual

Section 5: Disassembly

Motherboard removal

To remove the motherboard:
1. Make sure that the case cover is already removed. See
2. Remove the nuts securing the RS-232 and Digital I/O connectors to the rear panel. Remove
these nuts.
3. Place the edge of a flat-blade screwdriver in the notch on the front/rear inputs switch rod.
Carefully twist the screwdriver while pulling the rod from the shaft.
4. Pull the wires off of the pin connectors for the INPUT HI, INPUT LO, SENSE HI, and SENSE LO
front input terminal connections.
5. Remove the AMPS fuse holder, then use needle-nose pliers to grasp the AMPS wire near the
fuse housing.
a. Push the wire forward and down to snap the spring out of the fuse housing.
b. Carefully pull the spring and contact tip out of the housing.
6. Unplug the following cables:
a. Unplug the display board ribbon cable from connector J1014.
b. Unplug the transformer cables from connectors J1002 and J6.
c. Unplug scanner slots ribbon cable from connector J1012.
d. Unplug analog backplane connections J1008 and J1010.
e. Unplug the battery cable from J1017.
f. Unplug the fan cable from J1018.
7. 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. The final screw is near the rear panel next to J5.
During re-assembly, replace the board and start the RS-232 and Digital I/O connector nuts and the
mounting screw. Tighten all the fasteners once they are in place and the board is correctly aligned.
8. Slide the motherboard forward until the board edges clear the guides.
a. Carefully pull the motherboard from the chassis.

Card cage removal

After the motherboard has been removed, remove the card cage by removing the screws that attach
the card cage to the bottom of the instrument case.
5-4
Model 2701 Ethernet-Based DMM / Data Acquisition System Service Manual
Case cover removal (on page 5-3).
2701-902-01 Rev. B / December 2018