This article describe how to troubleshoot power supply failure on SRX345 device.
The SRX345 Firewall is available with either a single AC power supply (Junos OS Release 15.1X49-D35 and later), dual AC power supplies (Junos OS Release 15.1X49-D110 and later), or a single DC power supply (Junos OS Release 17.4R1 and later). The power supply distributes the different output voltages to the device components according to their voltage requirements. The power supply is fixed in the chassis and is not a field-replaceable unit.
Below are the steps to troubleshoot PSU issue.
Step 1 :-
Identify the defective PSU from "show chassis environment" command output and check if it is receiving the power from the respective source properly. If there is issue in power, like power fluctuation or no power getting received from the source, change the power source or troubleshoot it. (This step can be performed by site electrician)
Step 2 :-
If there is no issue with the power, then try to use spare power supply cable to identify, if the issue with the defective cable or not. After changing the spare power cable, if the Power supply changed from failed to OK, then the issue was with the cable and replacing the cable solved it.
Step 3:-
If there is no issue with the cable, then try power-draining the device to rule out any issue on the chassis.
Step 4:-
If none of the above step work, please open a JTAC case for further assistance.