Keithley 2002 Repair Manual

Troubleshooting
2-18
2.11.1 Memory element tests
These tests check the EPROM, RAM, and EEPROM memory circuits of the Model 2002.
Test 100.1 — EPROM
Type
Pass/fail
Fault message
Checksum error
Description
All ROM bytes (except checksum bytes) are read, a checksum is calculated and compared to the
stored checksum. Failure of this test indicates that one or more ROM locations cannot be read
properly.
Components
U637, U638 and associated logic.
Test 101.1 — RAM
Type
Pass/Fail
Fault message
Address bus open/short
Description
This is an abbreviated version of power-on RAM testing. Memory locations are written to and
then read back. It is highly unlikely that this built-in-test will fail. A unit with faulty memory
will probably fail the power-on memory test or will lock up intermittently.
Drawing reference
Digital Board; 2002-140
Components
U635, U636 and associated logic.
Test 101.2 — RAM
Type
Pass/Fail
Fault message
Pattern test failure
Description
A pattern of bits is written to each RAM location and then read back. This test performs a more
rigorous check of RAM elements.
Components
U635, U636, and associated logic.
Test 102.1 — EEPROM
Type
Pass/Fail
Fault message
Read/write EEPROM failure
Description
An attempt is made to read a byte of information from the 24164 configuration EEPROM (U632,
U633, U634), and an acknowledgment signal is verified. This is a hardware test only, and it does
not verify the validity of configuration information stored in EEPROM.
Drawing reference
Digital Board; 2002-140
Components
U632, U633, U634, and associated circuitry.

Keithley 2002 Specifications

General

Brand	Keithley
Model	2002
Category	Multimeter
Language	English