Special Handling Of Static Sensitive Devices; Disassembly Instructions - Keithley 263 Instruction Manual

MAINTENANCE
8.5 SPECIAL HANDLING OF STATIC
SENSITIVE DEVICES
CMOS devices operate at very high impedance levels for
low power consumption. As a result, any static charge that
builds up on your person or clothing may be sufficient to
destroy these devices, if they are not handled properly.
Use the precautions below to avoid damaging them.
1,
2
3.
4,
5.
6.
7.
ICs should be transported and handled only in con-
tainers specially designed to prevent static build-up.
Typically, these parts will be received in anti-static con-
tainers of plastic or foam. Keep these devices in their
original containers until ready for installation.
Remove the devices boom their protective containers only
at a properly grounded work strap.
Handle the devices only by the body; do not touch the
pins.
Any printed circuit board into which the device is to
be inserted must also be mounded to the bench or table.
Use only anti-static type solder sucker.
Use only grounded tip soldering irons.
Once the device is installed on the PC board, it is nor-
mally adequately protected, and normal handling can
lYSUIlW.
8.6 DISASSEMBLY INSTRUCTIONS
If it is necessary to troubleshoot the inshunent or replace
a component, use the following disassembly procedure.
An exploded view of the instrument may be found in
Figure 8-6.
WARNING
Disconnect the line cord and any cables from
the instrument before disassembly.
1. Remove the top cover as follows:
A. Remove the two screws that secure the top cover to
the rear panel.
B. Grasp the top cover at the rear and carefully pull up
until the tabs at the front of the cover clear the front
panel. The cover may then be pulled completely
Cl&%
C. To replace the top cover, reverse the above procedure.
Be sure to install the tabs at the front of the cover
before completely installing it. Also, make sure the
spring contact clips located on the rear panel make
contact with the top cover shield.
2. Remove the analog board as follows:
A
B.
C
Disconnect I'10 and I'll from the analog board. l'10
leads to the OUTPUT connecter and I'll leads to
PREAMP OUT and EXT INPUT.
NOTE: There may be another cable connector (l'l2)
located near the front of the analog board. If so,
disconnct I'12 from the analog board.
Grasping the analog board by the guarded shield,
carefully lift the analog board shield out of the
instrument.
Note: When reinstalling the analog board, make sure
the board is installed in the card edge guides (located
at the front and rear of the instrument) so that the
analog board mates properly with the mother board.
To remove the guarded shield from the analog board,
remove the eight screws securing the shield to the
board standoffs. Four screws secure the top (com-
ponent) part of the shield to the board and four
screws secure the bottom part.
CAUTION
Do not touch the PC board or any component
that is in the shielded area of the anloag board.
Contamination in this high impedance area will
result in degraded instrument performance. In
the event of component replacement or in-
advertent contamination, clean the board per
instructions in paragraph 8-8.
3. Remove the mother board as follows:
A. Using an IC puller, disconnect the display board rib-
bon cable (near the front of the instrument) from the
mother board.
B. Remove the six screws and collars securing the
mother board to the bottom case.
C. Remove the two screws that secure the rear panel
to the bottom case and remove the mother board and
rear panel as a single unit.
D. The voltage source shield can be removed by remov-
ing the four screws that secure it the mother board.
CAUTION
Do not touch the board or any components in
the shielded area. Contamination in this area
may result in degraded instrument perfor-
mance. If contamination occurs, clean the area
as described in paragraph 8-8.
8-13