When the connection is off, {TAIL ~ the photodiode} is disconnected from {HEAD ~ the substrate} and hence floats 
When the connection is off , { TAIL ~ the photodiode } is disconnected from { HEAD ~ the substrate } and hence floats
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH