atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Outside Plant OSP Construction Tell a youngster how to ground...

94astro - The DSX80 has a known problem with the COIU-A trunk card which affects longitudinal balance and creates the humm. You definitely need to ground ALL three of the ground lugs inside the DSX cabinet, but that may not solve your problem.
If you are a certified dealer, you can contact tech support and they will send you a COIU-B card which will correct the humm. Also, you may have to upgrade the system to .28 software.

Bill

For this install I did end up buying the DITEK unit (thanks fellas) and it did improve the humm a little, and fortunately zero complaints from the customer. I am running on the latest version .27.

A few months ago tech support sent us some DS1000 trunk cards to get rid of the humm and it didn't help at all, is the COIU-B card a new card made for the DSX?

Yes, the COIU-B is an improved version of the trunk card originally released for the DSX. I have a customer that had all the correct grounding, I tweeked all the gain settings but still had humm. Tech support sent be the COIU-B and, voila, humm gone!

Don't think for a minute that the COIU-B is a substitute for proper grounding as outlined by colleagues above. The DSX is still going through some tweeking and the COIU-B is one of those improvements. I have DSX systems in place with the COIU-A card and they also are properly grounded and don't have any problems with humm.

Bill

Good to know...

Same here, BillyBob. No hum reported on any of mine with the "A" line cards. Surge, UPS, and GROUND !!!!!

That's funny that you guys haven't experienced the humm, I've had it on every DSX I've touched (about 8), once it's grounded the humm is gone but there is still alot of sidetone.

They have gotten better with software upgrades, we really like the system, my boss likes it because it's inexpensive and I like it cuz it's easy to program and use with lots of features. Hopefully they've started shipping with the B trunk cards.

I don't think that the B card are general release yet 94astro. Atleast not from my supplier. I believe the only way to get one is thru NEC tech support at this time.

As for the sidetone. First try changing the loop length. I personally have not had much luck with that helping. After that change the recieve gain. I have found -4 to be pretty normal around here. But play with it and see if it helps.

Brian

I have played with the loop length and recieve gain, at one location we lowered the recieve gain too low and the voicemail wasn't hearing DTMF tones and was not transferring calls, and that install was auto attendant answer.

Right now we aren't getting any complaints anymore since all are at current software versions and grounded properly, the customers who are aware of the sidetone know that NEC is working on it and if we have to put the B trunk cards in then we will. It's been a pain, but again, we like the DSX.

Now that we have beaten the DSX hum to death, is there anything else we can do about the original post?



94astro, it appears from your posts that the DITEK will do the trick. Anything else?

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