This document is intended to help localize problems by indicating which boards are used for a particular test. First a few pieces of background information:
Sometimes VZ tests are performed as VF with connections reversed and vice versa. I will detail the conditions for this choice later in the document.
There is a SELFTEST routine running in the background at all times and if it passes, that eliminates a lot of potential problems, as follows.
The computer and tester are able to communicate with one another via the B621 board in the tester and the interconnecting cable.
- The dual DAC board B500 is pretty thoroughly tested except as relates to 1KHZ impedance tests.
- The B501 board, which is used as part of the common ADC is checked. However, there is a differential amplifier and an 8 channel mux on the B501 that are not checked by the SELFTEST. The differential amplifier is used to readout VF or VZ where the voltage is below 16V in most cases (see “switching points”). The 8-channel mux is used to connect the ADC input to the DAC output for SELFTEST, to the B552 output for high voltage VZ/BR or IR, the differential amplifier for low voltage VF/VZ or to the B530 output for impedance tests.
The DAC mentioned above is used to set the forcing level for all analog tests and the ADC mentioned is used to digitize the readings for all analog tests.
- Although the B621 board is used in a major way to do the SELFTEST, it does have many other inputs and outputs which could still be defective.
- The B400 board is used by all analog tests to provide precision low level reference currents or to do forcing range decoding or both.
- The B552 board is used for the “readout” part of the IR test (not the forcing) and for the readout of VZ/VBR tests where the reading is more than 16V. It is also part of the readout for the 1KHZ impedance tests.
- The B530 board is the other part of the readout of impedance and is not used for anything else.
- The B368 board is used only for the non-analog test for orientation and Kelvin contact checks. The FEC200 will function with both of these boards removed except that it will not do automatic orientation, Kelvin, or 1KHZ impedance tests. You can still test both orientations by using the F1 switch on the test line to force the tester to “flip” the orientation.
- The B502 boards (4) are used as the interface to the handlers or manual test stations. You can remove these also and the tester will still work using the <Alt><1> key to “start” the tester.
- The B509 relay multiplexor board is used only to switch the tester from station to station and the tester will run without it if the DUT is connected directly to the B508 relay board.
- The B534 board is used to force current for the VF test when actually done as a VF (not a VZ reversed). See the switching point page. It also supplies reference current for VZ tests above 4MA. For VZ tests below 4MA it is disconnected and the reference current is supplied by the B400.
- The B507 is used to force voltage or current for VZ or IR tests up to 500V but at levels where VZ is not done as VF reversed. For voltages over 500V the B411 board (top chassis) is used to supply the forcing voltage or current. There is a cable with a 9 pin plug that connects the control lines to the B411 board. Disconnecting this cable isolates the B411 for tests.
The purpose of mentioning boards that can be removed is to eliminate the possibility that a board can “load” the system busses or power supplies even if the board is not used directly by the test being performed.