Troubleshooting
2-2
2.2
Repair considerations
Before making any repairs to the Model 2002, be sure to read
the following considerations.
CAUTION
The PC-boards are built using surface
mount techniques and require special-
ized equipment and skills for repair. If
you are not equipped and/or qualified, it
is strongly recommended that you send
the unit back to the factory for repairs or
limit repairs to the PC-board replace-
ment level (see following NOTE). With-
out proper equipment and training, you
could damage a PC-board beyond re-
pair.
NOTE
For units that are out of warranty, com-
pletely assembled PC-boards can be or-
dered from Keithley to facilitate repairs.
1. Repairs will require various degrees of disassembly.
However, it is recommended that the Front Panel Tests
(paragraph 2.4) and Built-In-Test (paragraph 2.10) be
performed prior to any disassembly. The disassembly
instructions for the Model 2002 are contained in Section
3 of this manual.
2. Do not make repairs to surface mount PC-boards unless
equipped and qualified to do so (see previous CAU-
TION).
3. When working inside the unit and replacing parts, be
sure to adhere to the handling precautions and cleaning
procedures explained in paragraph 3.2.
4. Many CMOS devices are installed in the Model 2002.
These static-sensitive devices require special handling
as explained in paragraph 3.3.
5. Anytime a circuit board is removed or a component is
replaced, the Model 2002 must be recalibrated.
2.3
Power-on test
During the power-on sequence, the Model 2002 will perform
a checksum test on its EPROM (U637 and U638) and test its
RAM (U608, U635, and U636). If one of these tests fail the
instrument will lock up.
2.4
Front panel tests
There are two Front Panel Tests; one to test the functionality
of the front panel keys and one to test the display. In the event
of a test failure, refer to paragraph 2.7 for details on trouble-
shooting the display board.
2.4.1 KEYS test
The KEYS test allows you to check the functionality of each
front panel key. Perform the following steps to run the KEYS
test.
1. Display the MAIN MENU by pressing the MENU key.
2. Select TEST, and press ENTER to display the SELF-
TEST MENU.
3. Select FRONT-PANEL-TESTS, and press ENTER to
display the following menu:
FRONT PANEL TESTS
KEYS DISPLAY-PATTERNS CHAR-SET
4. Select KEYS, and press ENTER to start the test. When
a key is pressed, the label name for that key will be dis-
played to indicate that it is functioning properly. When
the key is released, the message “No keys pressed” is
displayed.
5. Pressing EXIT tests the EXIT key. However, the second
consecutive press of EXIT aborts the test and returns the
instrument to the SELF-TEST MENU. Continue press-
ing EXIT to back out of the menu structure.
2.4.2 DISPLAY PATTERNS test
The display test allows you to verify that each pixel and an-
nunciator in the vacuum fluorescent display is working prop-
erly. Perform the following steps to run the display test:
1. Display the MAIN MENU by pressing the MENU key.
2. Select TEST, and press ENTER to display the SELF-
TEST MENU.
3. Select FRONT-PANEL-TESTS, and press ENTER to
display the following menu:
FRONT PANEL TESTS
KEYS DISPLAY-PATTERNS CHAR-SET
4. Select DISPLAY-PATTERNS, and press ENTER to
start the display test. There are five parts to the display
test. Each time a front panel key (except EXIT) is
pressed, the next part of the test sequence is selected.
The five parts of the test sequence are as follows:
A. Checkerboard pattern (alternate pixels on) and all
annunciators.
