Hybrid Testing

Miscellaneous Information

On the hybrid connector, the bias line is on the side where the chips are located, also the edge where the sensors will be glued. On the green cables for the hybrid tester, the bias line is indicated by a black line on one edge of the cable.

There are two green cables, one towards the front edge of the table (closer to you as you face the apparatus) and one farther away. Use the one closer to you for individual hybrids or full modules with only one hybrid.

There are 3 power supplies connected to the system. The bottom and middle ones supply +/- 6V to the hybrid. The +/-20V outputs on the bottom supply are unconnected. The +/- 20V outputs on the middle supply should be set to 5V for the calibration chip. The top supply is used for applying back contact bias to full modules with Si. It should be current limited at a level of about 4-5 milliamps.

There is a separate readout board for String 0 (the upper one) and String 1 (the lower one). The system tests one string at a time. You chose which string is being tested by moving the analog output cable, the gray cable plugged into the brown right-angle connector on the back edge of the board.

Towards the front of the two readout boards, there is a row of 6 small blue rectangular pots, 5 of which have two pin testpoints in front of them. The pin on the right is ground. Use the adapter allowing you to plug the multimeter into these testpins. From left to right (from the center of the board to the outer edge), these are Vfp, Vfs, Ipre, Isha, and Ibuf. The nominal values (Nc = number of chips, Ns = number of strings) are Vfp = -350mV, Vfs = +700mV, Ipre = 500microamps*Nc, Isha = 14microamps*Nc, and Ibuf = 140microamps*Ns. Ipre is read out through a 100 ohm resistor giving 0.05 volts per chip, Isha is read out through a 1000 ohm resistor giving 0.014 volts per chip and Ibuf is read through a 100 ohm resistor giving 0.014 volts per string. Note that Ibuf normally doesn’t read anything. To get a reading, remove the leftmost (smaller) of the two ribbon cables at the back of the readout board. You may need to do this several times to get a reading. Don’t forget to plug the cable back in. Note that the current readouts only work on the board for String 0. If any reading is seriously off, a small screwdriver can be used to turn the screw on top of the blue pot. Turn very slowly and wait for the electronics to settle to check the reading.

The VI to be used (the Sensor calibrate shortcut) points to the file: C:\LABVIEW5.0\PhobosCalibration\SensorCalibrateV2-0.llb

On a module or hybrid, looking down at it with the connectors on the right, the strings go clockwise. On left-handed hybrids, string 0 is next to the connector, on right-handed hybrids, string 1 is next to the connector and string 0 is on the other end.

Instructions for Hybrid Testing

1) Transfer insert with mounted hybrid to the box mounted on the test station.

2) Use the anti-static bracelet when touching electronics.

3) Plug in the green cable. Note that the connector on the cable is too long. It should be plugged in so that the green cable is centered on the connector on the hybrid. Be careful with the connector, your fingers, the bond wires, Si (if present), etc. The edge of the cable with the black line goes on the side of the hybrid with the chips. You may need to flip the cable over to get the connector aligned properly.

4) Use 3-4 screws to tighten the test fixture cover, the black tape goes on the cable end. Light tightness is more critical if you are testing a module with Si and plan to use the back contact bias.

5) Plug in the fan to cool the test station electronics.

6) Turn on bottom two power supplies simultaneously for testing hybrids. The top power supply can be used to supply bias voltage for testing full modules. If you use the bias power supply, make sure to turn it up smoothly and slowly. Verify the operational voltage for the module first.

7) Check voltage and current readings. The bottom supply should read 6V (outputs are swapped to supply –6V to hybrid) and a current of about 0.05 amps per chip on the hybrid. The middle supply 6V has a slightly smaller current (~0.035 per chip). The +/-20V outputs on the middle supply should be set to 5V and should draw very little current (~0.01 amps). Currents on the MSDL/R hybrids are 20-40% higher due to the 128 channel chips.

8) Turn on NIM bin and pulse generator (below NIM bin). These should have some time to stabilize before you start the test.

9) Check that the pulse rate (indicated by the blinking lights on the NIM modules) is about 1-2 Hz. The top Vernier dial on the pulse generator adjusts the rate (Note that it adjusts period, so turning clockwise gives lower pulse rate).

10) Check the readout board voltage settings (see description on bottom of "Miscellaneous Info" page).

11) Click on the Sensor Calibrate shortcut to bring up the library list. Use the 3.1 version.

12) Fill in the following information near top left

Testing hybrid or module

Hybrid or module type

String number (Check location of analog readout cable!)

Serial number of hybrid or module

Number of tests should be about 50

The run number is an arbitrary increasing number.

13) Fill in the following near the bottom left:

Number of pedestal events should be about 100

Test type

Your name under operator

The filename will be created automatically when the program starts running

14) Fill in the information about current, etc. along the bottom edge. Ineg6 is the current on the bottom 6V supply. Ipos6 is the current on the middle 6V supply. The nominal current settings correspond to a peaking time of 1.1 microseconds. Don’t forget to enter the approximate temperature. Also, don’t forget to unplug the multimeter from the readout board when you are done entering info.

15) Click on the white arrow at upper left to start the program running.

16) The data source should be phdb.

17) Log-on to Oracle server phdb, user webuser, password (Ask an expert).

18) If not done already, create a folder in C:\Data with the hybrid or module name. Put the output file in this folder. Check to make sure the filename (including the hybrid/module number, the string number, and the run number) is OK.

19) The program starts running with new windows popping up occasionally, doing pedestal, noise, and about 12 calibration steps. You should see the signal stepping up on the blue histogram with each calibration step. The highest calibration test amplitude will be about 3900 mV. The first channel in each chip may look funny in this setup. Small (few millivolt) fluctuations in the output for the first few calibration steps are not a problem.

20) Check the results. The pedestal should be in the range of about –50 to –350. The noise should be about 1-2 mV. Check both pedestal and noise histograms for flat stretches indicating regions with no variation at all (almost certainly a problem). The calibration outputs should be roughly flat and close to equal for all chips. There may be small (no more than 10%) variation within a chip and from one chip to another.

21) When the test are all finished, you will be asked if you want to write to the database. After you click on OK, you will have about 30 seconds to write comments in the box at lower left. The program will ask you if you need more time.

22) Database writing is very slow. There is an indicator at the upper right to monitor the (snail-pace) progress. This is a good time to take a break.

Testing the next string

1) This is very easy! Just switch the analog output cable on the readout board, update the Analog string number on the screen, change the run number, and hit the white arrow to start running again.

Finishing Test

1) Use the anti-static bracelet when touching electronics.

2) Turn off the bias supply (if used). Turn it down slowly and smoothly.

3) Turn off bottom two power supplies simultaneously. Leave the voltage setting knobs unchanged and just turn off the power switches.

4) Remove the test fixture cover and unplug the green cable. You may need to wiggle the cable connector a bit to get it to pull off. Be very careful about your fingers, the bond wires, Si (if present), etc.

5) Transfer insert with mounted hybrid back to its transport box.

6) Mark test results on the log sheet on the transport box.

7) Check results in the assembly database. Follow links Detector > Assembly > Assembly Database > Click on correct hybrid type > Click on correct hybrid > Next to "Calibration of Hybrid", click on P, N, G, and V to verify results. C link gives a comparison to the results IDE sends us.

8) Log acceptance in the database. On the hybrid table, next to "All chips functional", click on Add, fill out table, and write to database.

9) Unplug the fan.

10) Turn off NIM bin and pulse generator (below NIM bin).