Other SOS Detection Circuits 
 
SOS Detect (P, SC, and SS Board) 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 42 
 
This drawing is used to verify an SOS condition that may have originated from the P, 
SC, or SS Board. The connector information should be used for troubleshooting 
purposes. Instead of using a peak hold voltmeter, the power supply connector of the 
board causing the blinks of the power LED may be disconnected to see if the unit 
remains on after power up. If it does, this usually indicates that the problem is located in 
the disconnected board. If the power LED continues to generate the same amount of 
blinks, more troubleshooting is required.  
 
Note: The unit will become totally inoperative if the power supply to the D and DG 
boards is disconnected. The system control circuit will be unable to power the unit and 
monitor the SOS lines. 
 
 
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