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Chapter 5 Service
Self-Test Procedures
98
Self-Test Procedures
Power-On Self-Test
Each time the power supply is powered on, a set of self-tests are performed.
These tests check that the minimum set of logic and measurement hardware
are functioning properly. The power-on self-test performs checks 601 through
604 and 624 through 634.
Complete Self-Test
Hold any front panel key except the "Error'' key for more than 5 seconds while
turning on the power to perform a complete self-test. The power supply beeps
when the test starts. The tests are performed in the order shown below.
601
Front Panel Does not respond The main controller U17 on the top board
attempts to establish serial communications with the front panel controller U7
on the front panel board. During this test, U7 turns on all display segments.
Communication must function in both directions for this test to pass. If this
error is detected during power-on self-test, the power supply will beep twice.
This error is only readable from the remote interface.
602
RAM read/write failed This test writes and reads a 55
h
and AA
h
checker
board pattern to each address of ram U14. Any incorrect readback will cause
a test failure. This error is only readable from the remote interface.
603
A/D sync stuck The main controller issues an A/D sync pulse to U17 and U18
to latch the value in the ADC slope counters. A failure is detected when a sync
interrupt is not recognized and subsequent time-out occurs.
604
A/D slope convergence failed The input amplifier is configured to the
measure zero (MZ) state in the 10 V range. This test checks whether the ADC
integrator produces nominally the same number of positive and negative slope
decisions (
±10%) during a 20 ms interval.
605
Cannot calibrate rundown gain This test checks the nominal gain between
integrating ADC and the U17 on-chip ADC. This error is reported if the
procedure can not run to completion due to a hardware failure.