Changes

It is important to determine light yield of each fiber before shipment to Jefferson Lab.  In order to do this, light yield tests will be performed on each fiber in our dark box using a red laser diode on a pulsing circuit.  The setup of the fibers is very important, as any offset fibers could give an inaccurate result.  It is also important that procedure is followed to prevent damage to electronics.   

It is important to determine light yield of each fiber before shipment to Jefferson Lab.  In order to do this, light yield tests will be performed on each fiber in our dark box using a red laser diode on a pulsing circuit.  The setup of the fibers is very important, as any offset fibers could give an inaccurate result.  It is also important that procedure is followed to prevent damage to electronics.   

'''If the electronics are powered and the dark box is open, the silicon photo-multipliers WILL be damaged''', so it is very important to make sure electronics are off before the dark box is opened.   

'''If the electronics are powered and the dark box is open, the silicon photo-multipliers (SiPMs) WILL be damaged''', so it is very important to make sure electronics are off before the dark box is opened.   

==Fiber QA Troubleshooting==

==Fiber QA Troubleshooting==

**Check that each fiber is flush against the chimney edge using touch, and finally, visually inspect using the light/mirror.

**Check that each fiber is flush against the chimney edge using touch, and finally, visually inspect using the light/mirror.

**If any fibers are not flush against the edge, re-do the previous step.

**If any fibers are not flush against the edge, re-do the previous step.

*'''Have a lab technician check the fibers at this step.''' The fibers cannot be too far into the chimneys or else they will damage the SiPMs when the board is replaced.  

*'''Have a lab technician check the fibers at this step.''' The fibers must not be too far into the chimneys or else they will damage the SiPMs when the board is replaced.  

*'''A grad student or lab technician''' must put the SiPM board back into place. Apply even pressure to the ends of the preamp boards until they are in place. Do not push so hard that it is bending the backplane. If needed, just place the preamp support end and screw it into the preamp supports until they are flush.

*'''A grad student or lab technician''' must put the SiPM board back into place. Apply even pressure to the ends of the preamp boards until they are in place. Do not push so hard that it is bending the backplane. If needed, just place the preamp support end and screw it into the preamp supports until they are flush.

*Close the main dark box opening and lock it tight to ensure that it is light sealed.  

*Close the main dark box opening and lock it tight to ensure that it is light sealed.  

*Turn on the power supply for the pulser and the op-amp first. Check that the voltages remain constant at 1.5 V and -10 V. Next turn on the power supply for the pre-amps and backplane electronics starting with the power for the control board.  

*Turn on the power supply for the pulser and the op-amp first. Check that the voltages remain constant at 1.5 V and -10 V. Next turn on the 60 V power supply for the pre-amps followed by the remaining power supplies. When turning off the voltages make sure the 60 V power supply is the last one turned off.

**Watch the control board's power supply current. If it exceeds. 0.38 amps, let a lab technician know immediately!

**Watch the control board's power supply current. If it exceeds. 0.38 amps, let a lab technician know immediately! The power supplies may have turned on in the wrong order or the pins on the backplane are making contact through the gasket.

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|[[File:LH-FiberQA_PulserPower.jpg|thumb|center|A view of the power supply powering the pulser and op-amp.]]

|[[File:LH-FiberQA_PulserPower.jpg|thumb|center|A view of the power supply powering the pulser and op-amp.]]