Self Tests - Stanford Research Systems SR844 User Manual

1. Self Tests

The self-tests check the lock-in hardware. These are functional tests and do not relate to the
specifications. These tests should be checked before any of the performance tests.
Setup
No external setup is required for this test.
Procedure
1) Turn the SR844 power switch off. Then turn the unit on while holding down the Setup key. Check
the results of the DATA, BATT, PROG and DSP tests.
DATA
Performs a read/write test to the processor RAM.
BATT
The nonvolatile backup memory is tested. Instrument settings are stored in
nonvolatile memory and are retained when the power is turned off.
PROG
Checks the processor ROM.
DSP Checks the digital signal processor (DSP).
The results are displayed on the Reference display (PASS or FAIL).
2) This completes the functional hardware tests. Enter the results of this test in the test record at the
end of this chapter.
Performance Tests
SR844 RF Lock-In Amplifier
5-5