Description of the problem

The NG-SDH OSN1500 equipment master is dual paired and one of the PIUs reports a power_abnormal alarm. The measured voltage is -53 volts. Replacing the PIU also reports the same alarm, and reversing the main control board also reports the same alarm.

Dial to the -60 jumper, found that the report is not reported, dial back or reported. After replacing the master control, it still reports, and it is normal to put the replaced master control on other network elements.

Process

None

root cause

According to the field test two PIU output voltage, input current difference is very small, and the voltage range between -41V ~ -60V, is a normal range, so exclude the PIU and the input power supply problem, then the problem is focused on the main control. However, the same report to replace the main control board, and the replacement of the main control to other network elements on the normal (here on the front of the problem of the localization of misleading, that the main control is good. After further confirmation of the site just replaced a master control).

This is because the principle of dual master detection -48V power alarm is as long as one of them detects -48V is not normal, the alarm will be reported, regardless of whether the master control is the main or standby. Therefore, as long as one of the main control failed to cause false alarms, the main backup swap is not able to eliminate the alarm. The piece of master control that was replaced is a good piece, so even if a piece of master control up, will continue to report, and the good piece of master control to other network elements will of course be normal.

Solution

Focus on identifying the faulty master control, and the master control if the corresponding 48V fault detected, the PWA or PWB indicator on the panel of the pull handle bar will be lit, so to change the PWA or PWB on the red light of the master control.

To the first 48V, for example, if only a master control PWA red light, it shows that the master control check 48V1 bad, replace it. If the two master PWA are lit red, it means that the master should be good. Need to check the front of the first PIU output, if the PIU output is also normal, it may be the master control and sub-frame with the problem. In short, it is to pay attention to observe the two master control which light red, which light green, replace the red light.

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