Stanford Research Systems SR865A Operation Manual page 201

Appendix G Performance Tests 183
If A Test Fails
If a test fails, you should check the settings and connections of any external equipment
and, if possible, verify its operation using a DVM, scope or some other piece of test
equipment.
After checking the setup, repeat the test from the beginning to make sure that the test was
performed correctly.
If the test continues to fail, contact Stanford Research Systems for further instructions.
Make sure that you have the unit's serial number and firmware revision code handy. Have
the test record on hand as well.
SR865A DSP Lock-in Amplifier