In-Circuit Test – Capturing and Analyzing Real Time Functional Test Data on Keysight (HP Agilent) 3070
Recently, one of our customers approached us with a unique project. They needed an ICT program and test fixture for the Keysight (Agilent) 3070 in-circuit test platform, which would not only perform in-circuit test, device programming but also carry out a functional test using a PC that would communicate with the board through the tester using an RS232 port. For this project, we designed and built a Functional Dual Stage Fixture. As the name suggests, the fixture operates in 2 stages: one for performing in-circuit test and the second for executing a functional test. When the fixture is used to conduct in-circuit test, the tester vacuum pulls down to actuate the shorter probes. However, a functional test cannot be performed when all these probes are in contact with the unit under test (UUT). As a result, for the functional test sequence to be done, we had to come up with a method that would allow only certain probes to make contact with the circuit assembly. To achieve this, we incorporated 2 elements into the fixture. This first was to have 2 probes lengths – long and short. The second was a system that would disengage the vacuum yet allowing the long probes to maintain their contact points. The way the fixture operates is that when the vacuum is turned on all probes are actuated allowing the execution of in-circuit test and device programming. After this stage is complete and before the vacuum is turned off, a switching mechanism activates the 4 solenoids. This action causes a latch to engage the hooks installed on the fixture cover, which prevents the fixture’s face plate from returning to its normal resting position. At this point, the vacuum is released and only the long probes are in contact with the board. Consequently, the functional test can be carried out. During the functional test process the UUT needs to communicate, through a RS232 port with a PC, that is connected to the tester. During this process the PC sends commands to the board and checks to determine if the UUT is responding correctly. This requires that information be captured and analyzed in real time. The following screen shot displays a report showing the results of the functional test. The test has checked the type of firmware that was programmed into the device, which is distinguished from the available 6 versions. Every line of this report shows a power-on self test that informs the operator which section of the self test has failed or passed.