6-5
CAUTION
U637 and U638 are static-sensitive
devices. Be sure to adhere to the han-
dling precautions explained in para-
graph 6.3 when replacing these devices.
4. Using an appropriate chip extractor, remove U637 and
U638 from their sockets.
5. Install the new ROMs in the appropriate sockets, mak-
ing sure that pin 1 for each device is properly oriented.
NOTE
The odd-addressed ROM must be installed
at U637, and the even-addressed ROM
must be installed at U638. The instrument
will not operate if the ROMs are incor-
rectly installed.
6.8
Instrument re-assembly
The instrument can be re-assembled by reversing the previ-
ous disassembly procedures. Make sure that all parts are
properly seated and secured, and that all connections are
properly made. To ensure proper operation, shields must be
replaced and fastened securely.
WARNING
To ensure continued protection against
electric shock, verify that power line
ground (green wire attached to AC
power receptacle) and the power trans-
former ground are connected to the
chassis. Also make sure that the exter-
nal ground screw is properly secured
after installing the case cover.
6.9
Assembly drawings
The following assembly drawings are provided to assist in
disassembly and re-assembly of the instrument. Also, the
Keithley part numbers for most mechanical parts are
provided in these drawings.
• Front Panel Assembly; 6517A-040
• Analog Shield Assembly; 6517-050
• Chassis Assembly; 6517-051
• Rear Panel Assembly; 6517-052
• Chassis Assembly (Analog Side); 6517-053
• Chassis Assembly (Front Panel and Transformer
Mounting); 6517A-054
• Chassis Assembly (Digital Side); 6517A-055
• Chassis Assembly (Case and Handle); 6517A-057