Stanford Research Systems SR844, User Manual

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5-4 Performance Tests
SR844 RF Lock-In Amplifier
DC Voltmeter
Range 20V, 4 1/2 digits
Accuracy 0.005%
Recommended Fluke 8840A
Terminations
50
Ω
BNC Cables
Various lengths
Front Panel Display Test
To test the front panel displays press Local and Setup keys together. Some of the front
panel LED’s will turn on. Press
+90
°
to increase the number of illuminated LED’s and
Phase to decrease the number. Use the knob to move the selected LED’s across the
panel. Make sure that every LED can be turned on. Press any key other than
+90
°
,
Phase
or Zero to exit this test mode. Note that the instrument is still operational; only the
display is in test mode.
Keypad Test
To test the keypad, press the
Ref Z-In+Source
keys together. The CH1 and CH2
displays will read Pad Code , and a number of LED indicators will be turned on. The
LED’s indicate which keys have not yet been pressed. Press all of the keys on the front
panel, one at a time. As each key is pressed, the key code is displayed on the Reference
display, and the LED nearest that key turns off. When all of the keys have been pressed,
the display will return to normal. To return to normal operation without pressing all the
keys, simply turn the knob.
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 other 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 instructions. Make sure
you have the unit’s serial number and firmware revision code in hand. Have the test
record with you also.