How to Trouble-shoot Morley Panel Earth Fault to (–VE or +VE) on External Wiring

[#1]

Issue

The Fire System Annunciator is displaying Earth Fault to –VE on external wiring (or +VE)

Solution

Take a meter set to DC voltage in order to isolate the fault with these following steps:

1. There are 5 wires that come from the power supply on the motherboard…. Blue, grey, red, black and green/yellow.
2. On a normal panel between earth ground (green/yellow) and black (DC negative) there should be about 1VDC.
3. If the voltage is below 0.3VDC the panel will be in –VE fault.
4. If the voltage is above 1.5VDC the panel will be in +VE fault.
5. In order to find out what loop is faulted, remove the wires one at a time with a meter connected to the terminals in step 2.

Part numbers D10024A, D10024, D9024, D8024