Reason for the service: The detector counts more than 10 times compare to the detectors above, left and right of it. Will examine it if:

• The detector is light tight
• If the AVD is damaged
• If there is radiation damage to the scintillator (not related to the above problem)

1. LED check with multimeter:
   • Forward bias 1.75 V
   • Backward bias, open
2. Dark counts, trigger 30 mV :

• Visual inspection of the SCI
  • No yellowing, signs of mechanical damage on the surface.
  • Under UV, no spots

The Standard operating voyage is 1100 V, I_l = 739 uA, counting rate bellow 5 Hz