10058 - With the alarm/fault condition in question indicated on the SC-770 controller...

With the alarm/fault condition in question indicated on the SC-770 controller display, measure the voltages at the GPRB relay output connector J2.

• Gamma alarm (red strobe and speaker): Pin 1 (brown wire).
• Neutron alarm (blue strobe and speaker): Pin 4 (blue wire).
• Fault (amber LED): Pin 7 (orange wire).

During a POST or alarm/fault condition, voltage should be  ~0.0 VDC.
If no alarm or fault is indicated on the SC-770 controller display, voltage should be ~12 VDC.