Monday, October 27, 2014

What is POST & JIG Test for Hardware?

What is POST & JIG Test for Hardware?

Power-on self test Abbreviated POST.
A set of diagnostic programs loaded from ROM before any attempt is made to load the operating system; designed to ensure that the major system components are present and operating. If a problem is found, the POST firmware displays an error message on the screen, sometimes with a diagnostic code number indicating the type of fault. The number of preamp channels is close to 60,000 including spare parts.  It is highly desirable for each one to be tested to pass a simple "go - no go"   test before being installed in the detector.  There are a large number of channels so the manufacturer will be testing the preamps. 

The test jig will have two functions: 
1) to check that the preamp can hold voltages applied to the power rails, and that the supply currents drawn are within tolerance, and 
2) to provide a fast electronic pulse that is applied to the input of the preamp and compare the output waveform to an expected shape.  The tester is also designed to be operated conveniently and quickly.

Five go-no go test jigs will be built to test the upgraded Calorimeter preamplifiers.  Two will be configured for Calorimeter preamp testing and three for ICD testing.  Two of the test jigs will stay at Fermi lab, two will be sent to the preamp manufacturing vendor, and the ICD group will use one. The manufacturing vendor will automate the tests during the production run so the test jig was modified to accommodate their automation needs. 

To conduct the tests, the operator will be required to place a preamp into a zero insertion force (ZIF) socket, push a button, and either read a voltage measurement from an externally connected meter or view an oscilloscope measurement of the rise and fall time.   To conduct the undershoot/ overshoot test, they will generate a comparison curve based on units that pass the current, rise, and fall time tests.

The test jig consists of three printed circuit boards; the digital control, ZIF, and LED display boards.  Modifications are currently being implemented which allow the vendor to measure the preamp power supply current.  Each jig is calibrated with the aid of a written test procedure to insure thoroughness.  A preamp power supply current simulation circuit has been designed for use during the calibration process to insure caliber.

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