atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's HDSL H4 Problem

Is there a mid-span repeater being used?

Anyway you cut it you will have to loop the doubbler from both the CO and the Remote card, run your tests and sectionalize the trouble.

Did you check the bonding and grounding of the cable?

It's probably noise on the cable from the 40 other hi-caps. If you can get your hands on a spectral noise analyzer (JDSU hst-3000c has one built in) you would be able to prove it. If you pulled the pm data from the other ckts in the cable, they would probably be showing intermittent errored seconds also, just nobody is noticing.

How to fix? Fiber... or you could try putting loop 1 in one binder and loop 2 in another or if there are spares going to the splice where the can is, try throwing 2 pairs into it that are not in the binders with the other 40 ckts.

Good luck

Don't know if a solution was found or not but, if the span is Adtran HDSL4 you should be able to sectionalize the hdsl span errors with the pm data. If the pairs scope clean with a TDR from both directions and you verified no Hi-Res opens, then I would wideband(not insertion loss test!!)the pairs with a 965DSP/FED or CopperPro/Terminator FED and look for wideband noise, wideband long-balance, and spectral interference. If any pair fails wideband noise everytime I would start looking for a bonding/grounding. If it fails wideband long-balance you have a pair trouble that you missed or it cannot be seen with the TDR

John is right. You need to isolate which section is running errors before/after the doubler before you start running the copper.

On a side note to a poster above. All HDSL technologies are analog carriers for DS1. The Doubler or HRE4(HDSL range extender)is really nothing more than a span powered hdsl modem in between the HLU & HRU

sorry I didn't come back. 4 days in trying to fix it & the circuit ended up being moved to fiber that was heated up during the repair.
I ended up getting another repair at the same prem so instead of working on it for days I ended up building a new span in a different cable to restore service.
The trouble is errored seconds to the doubler & when moved to a different count away from the 40 hicaps the es move to between the doubler & niu. There are onlya 100 pairs of this count that goes to the sai & this is the count that has around 40 other hicaps in it.
Next time I am out there I will run the wideband noise. Have not run that test before so will have to look it up.

Your on the right track! Like "whynot" posted there might be just one too many hi caps on the count.

PS: Did the trouble move to between the doubler and the NIU or did you eliminate half your trouble by moving the IN portion?

We had moved the in portion of the makeup. So it does seem to point to another hicap causing it. I have not been back in a week so the next one that goes down I will try separating the T & R pairs in the 100 pairs group & see if that helps.

If you get the opportunity see if there are any T1's in the count that should have been disconnected but were not physically removed and/or the customers have not removed their equipment. Just possibly there could be a piece of equipment still connected that is putting out zeroes on the dead T1 screwing up the timing and synchronization circuitry in the regenerative sections of other T1’s.