Loss of timing on power port - 900AP

I have an issue with losing the sync on the power ports on 900 APs.
We have 3 APs mounted 225’ up on a 400’ tower, all are grounded within 2ft to the tower ground system, using shielded cat5. Timing is supplied from a cmm over the ethernet. The APs, one or more, will lose their ability to receive timing over the power port after a possible nearby lightning strike. You can set them to generate sync and they work fine except for the inherent problems of not being synced. These are integrated units, our other installations use connectorized APs and don’t seem to suffer this problem.
We have checked and reinforced tower and power grounding. All ethernets have motorola surge protection devices. Is this common with the integrated devices? A repair shop we’ve consulted with indicated this is a common problem. Any others out there seeing anything similar? If so, how do I prevent this from recurring?

Same issue here with one of our sites… however, we are not sure what causes it as we have gone thru two CMM. they start working good and just about 4 to 5 hours after we replace it looses it sync again. In the first case it was port #1. After moving the AP cable to a different port, it continued to work perfectly for many weeks. We decided to replace it since it was still under warranty and we feared it would happen again. The new CMM lasted 4 hours. port #1 and #2 went to crap. The only difference this time is that, somehow, we were able to make them work again, but it only lasted about 5 hours again. We think there is a conflict of timing as this site has cables to take timing from a remote CMM thru a BH slave and thru the ethernets at the same time. The only other thing we can blame are the cables as they are pretty close to 300 ft in length. We haven’t done any more troubleshooting. If we do, I’ll post it here.

Our case has been strictly a problem with the APs not receiving sync off the power port. Moving the ethernet to another good/unused port in the CMM and also replacing the cmm did not correct the problem. Replacing the AP has been the cure every time. However, that gets to be an expensive proposition.

We’ve noticed a similar problem. We only use Lastmile 360 AP at this time and have had 2 AP that won’t sync via the Power Port and another that wouldn’t even power up. We talked to Lastmile about it and they said that they have been getting alot of customers calling in about the same problem, they said it’s a Motorola Manufacturing problem. BUt who knows for sure.

Keep in mind this is what WE were told.


I just installed my first tower with 6 900 integrated APs. We installed STP on the timeing port also to allow reset jumper from the ground. None of the APs receive sync. Turned out the AP could detect 200 ft of STP and refused to sync on power port. Changed ends to pin 4 and 6 only and the APs came up fine.

Vaughn MacEntee
Basic Internet, Inc.