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Repeated errors - digital trunking clock in free run

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argent3993

Programmer
Dec 5, 2010
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In the last 48 hours, my BCM 450 (R5 - fully patched) has started kicking out error 75 - Digital trunking clock in free run. This error has been generated about 30 times over the last 48 hours. Even with the errors, we're not experiencing any call drops or any other oddities. Never seen this issue with the BCM in the 2 years we've had it.

I've checked the clocking on the PRI card - it's properly set to Primary External. I contacted the telco to run a test on the circuit and they say it's clean.

I've both warm-reset and rebooted the BCM and am still getting the errors.

Any ideas?
 
Not yet. Wanted to run the initial trap with the telco. I contacted them and they've been monitoring the circuit since late Monday when this first started occuring (or so they say) and haven't seen anything unusual.

Will be contacting the vendor next - but wanted to see if I was overlooking anyting obvious before paying for a service call. :)

 
In my experience, it's always been the Telco. All that you can do now is to swap out the DTM PRI module. They aren't known for failing!.

In the UK, we have a number of customers with PRI provided via copper dropwire using bunched pairs. It's common for the link to lose it's sync and go into Free Run.

All the best

Firebird Scrambler
Meridian 1 / Succession and BCM / Norstar Programmer in the UK

If it's working, then leave it alone!.
 
Well, I actually have a spare PRI module. :) It's actually already seated in the BCM but is not in use. When we originally put the system in, we had 2 PRI circuits coming in but have since downgraded to a single PRI. I'll bring the other one back online and see if I get the same results.
 
Before you do it, Check the dip switches on the second PRI as they need to be the same as the one already in the BCM system.

Its not recommended to hot swap out the modules, so you would need to power down the BCM and change out the modules. I'd just swap out each other with the dip switches etc and power up again.

If you are still having issues, then give your Telco a good push!.

All the best

Firebird Scrambler
Meridian 1 / Succession and BCM / Norstar Programmer in the UK

If it's working, then leave it alone!.
 
Actually in a 450 the dip switches in the main cabinet are all on.

Since the 2nd DTM was in use at one time you should be able to check which Line Pool its in and then change the route destination code 9 uses to that line pool. Then just move the patch cable from one DTM to the other.
 
Yes - it was a simple reconfig. I just renabled the PRI card in Element Manager, verified the line pools were still set the way I wanted, and then moved the PRI cable from one module to the other. Made a few test calls to verify functionality and all is good.

Been running for 3 hours now without any errors - will see what happens overnight.
 
Quick update - it's now been 14 hours since I switched to the spare PRI module and have yet to experience the error. It's not a sealed deal quite yet, but it sure looks like the problem was with the original PRI module.
 
That is certainly possible but extremely rare.

SHK Certified (School of Hard Knocks)
NCSS, ATSP/IP
 
I had these errors once. It wouldn't happen as often as yours but it WOULD happen about the same time every day (4x a day, usually).

I had many theories. I thought that since I was using UTP to carry the T1 about 200ft from the smart jack that ballasts from the lights were causing the problem. I eventually had my coworker run STP between the smartjack and the DTM and the problem continued. I had swapped DTMs and it hadn't helped. Changed the clocking to every possible setting. Called the telco and they swore it wasn't them. Finally I had bought T1 to fiber media converters and was about to try those when my circuit goes totally down. Telco comes out and replaces smartjack and some other stuff I wasn't clear on. After the circuit is restored I don't have the errors any more.

Moral of the story? There isn't one, really. These type of problems suck to troubleshoot I guess.
 
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