Detector Electronics Checkout

1. If there is any possibility that the DC or Clock voltages are not set correctly (first power-up for a run, for example, or a new set of cards), disconnect the DC and Clock cables from the top of the dewar before turning on the detector power, then perform steps 2 through 5. Otherwise, proceed to step 6.

2. Set the Filter wheel to the block position (10.00 on the odometer) if it is not there already. You can turn the gears by hand.

3. Turn on the Clock, PreAmp, and Co-Adder power, in that order. On the power supply, this means turning the switches on from right to left. When turning the electronics off, reverse the order. The switches are wired so that the PreAmps cannot be turned on before the Clocks, and the Co-Adder cannot be turned on before the PreAmps. In an emergency, all three can thus be turned off flipping the rightmost switch, but turning everything on and off in order will put less strain on the electronics.

4. Connect a DVM to the DC voltage connectors on the PClock box, and check all the voltages against the table on the side of the PClock box. Check channels 1--12 on the selector switch at the top right of the front panel, and 13--24 on the switch near the bottom. Use only the voltage table on the side of the PClock box because the settings usually change when a new detector is installed. Adjust the pot settings on the DC cards if necessary.

   Some of the voltages (V_OD, for example) may change slightly when the detector is drawing power, so if a few are off by a couple tenths of a volt don't worry too much. Be sure to check them again once the detector is fully connected.

5. (Optional) Connect an oscilloscope to the Clock signal connector, and verify the clock levels against the values in the table on the side of the PClock box.

6. Turn off the PClock power.

7. Connect the DC cable from the PCLock box to the dewar first (it grounds the detector). Then connect the Clock, Signal, and Monitor cables. The PClock connectors line up with the corresponding dewar connectors; no two cables should cross.

8. Turn the power supply back on.

9. Turn on the PC. After the PSYS program starts automatically, exit it by entering EX from the main menu. Then type psys GRB. This is necessary so that the PC will listen for a connection from GRB, instead of the default ezra. If PSYS is already running, type RO 8 from the main menu to initialize the PClock box. If the error message ``Cannot detect chopper'' appears, there is probably a missing cable, possibly the Chop In to Chop Out on the PClock box.

10. The red light on the side of the PClock box should go off and the yellow one should come on after PSYS is running; this indicates that the default ROM table information has been successfully transmitted.

11. (Optional) Connect an oscilloscope to the Signal BNC at the top of the PClock box, preferably using a test probe. Sync the scope on the Scope Trigger BNC. You should be able to see the Signal, Reset, and Pedestal levels of the detector clocking pattern. The Reset should be the highest voltage, at slightly under 5V. Adjust it using the trimpots on the PreAmp cards. Be sure to make this adjustment for all four detector channels.