Hum on ls/gs lines on an opt 11

[jbrock1]

I have an opt 11 that has a loud hum on all of the ls/gs lines. The problem is on all trunks on two cards. I've swapped
trunk cards with new ones, replaced the power supply, removed the system ground and reconnected it. I checked the system ground versus the power ground and its okay. The hum is present on the lines only when they are connected to the system. If I remove the bridging clips or disable the cards the hum goes away. They're set up as timp=600 Bimp=3com. Any suggestions? Thanks

 

[nortic]

2 THINGS I WOULD DO

1)VERIFY GROUND START OPERATION AT DEMAC WITH TEST SET.
MAKE SURE ITS NOT LOOPSTART AND POLARITY IS CORRECT.
2)VERIFY JUMPERS ON CARD ARE SET FOR CO
REFER TO PLANNING AND ENGINEERING,TRUNK CARDS NTP
FOR CORRECT VINTAGE

 

[nortic]

AND IF AVAILABE TRY A LOOPSTART POTS LINE ON A PORT PROGRAMMED AS LOOP TO SEE IF YOU HAVE A HUM

ARE THE TRKS ON A SLIC FROM CO THEY MAY NOT BE SET RIGHT

 

[PERRYPJ]

DO YOU HAVE ANY ANALOG CARDS IN THE SWITCH, IF SO TAKE AN EXTENSION AND RUN IT TO THE TN OF ONE OF THE TRUNKS THAT IS HUMMING MAKE SURE YOU CHANGE IT TO A LOOP START TRUNK.
SEE IF THERE IS A HUM

OLD ROLMEN WORKING ON NORTELS

 

[jbrock1]

I've verified the polarity/programming/jumpers on the ground starts and it is correct. I've since found that the hum is not as noticeable on the loop starts, actually you can barely hear it on a system phone. This just started occuring recently. I've placed an order with Verizon to swap the ground starts to loop starts since you can barely hear the hum on them. I realize that this is just putting a band-aid on the problem but it should work. Plus LS lines are cheaper.
Thanks for the help.

 

[vztech]

I hope you dont have a MMail on this system. Loop starts are not recommended. Make sure its not your Anlg cards with the hum. try reseating all the anlg cards first.

 

[jbrock1]

I'll give it a shot. Thanks vztech. Also theres not a mmail.