The tracker is controlled by a TKR TEM board in a VME crate called TKR VME (Figure 1). Eight shielded cables connect the TEM board to tracker readout electronics through eight repeater boards. The repeater board is a small printed-circuit board attached to the base plate of the tracker, to buffer signals from the tracker and to filter the power supply lines (See section 3 for more explanations). All the electrical connection for the tracker, such as power lines and signal lines, are on those eight cables.
Detector bias and power for readout electronics are supplied by the Tracker Power Supply connected to the TEM board. It converts 28 V input into all the power lines that the Tracker Tower needs: detector bias, DVDD (digital power), AVDD (analog power), and AVDD2 (2nd analog power). The repeater boards are powered from the digital power DVDD. The TKR VME crate also includes a CPU board with an Ethernet port. On the CPU board, VxWorks is running as an operating system to control and access the TKR TEM board. The VxWorks system is controlled through the Ethernet connection.
Figure 1: Schematic drawing of pre-flight setup for the BFEM tracker
Before applying detector bias, check the compliance level. Start with relatively low voltage like 2 V, slowly raise the voltage with watching detector current every time you raise the voltage. To be safe, raise the bias with 1 V step up to 10 V and with 10 V step afterwards. You might see detector current reach compliance level when you raise the voltage. You should wait for a couple of seconds until detector current gets down below compliance level before raising it to the next voltage level.
Here is a list of instruments for the tracker part of the setup below. Also, setting of power supplies are shown in Table 1 with typical currents listed.
Table 1: Power Consumption of Tracker Power Supply