Digital Expansion Interface makes phones go down when powered up

[Camoron]

Hi all... I have a client with whom we installed a DEI to add additional digital extensions. The DEI is daisy chained to the DEI above it and then to the system chassis itself. When the new DEI gets powered up it takes down all the digital phones in the office, none of them get dial tone and the displays either freeze or get Major Alarms.

[Matt_Womack]

What cards are in this DEI?

Have you tried booting the DEI up without any of the cards inserted, then inserted them one at a time?

I've had this same issue and it turned out to be a bad card.

[Camoron]

We have two DEM 16 cards, we have tried inserting them one at a time. With no cards inserted, it works, but with either of the two cards inserted it takes the system down. Is it a bad DEI chassis?

Edit: We just tried with a known-good card that they had in a working DEI, and it still didn't work. Definitely thinking it's the DEI itself.

[Matt_Womack]

Do you have any spare DEM-16 cards in a known-good condition? I would want to make sure the cards were the issue before I move on to the DEI itself.

EDIT: Swap w/known-good DEI, as you probably already are doing. It's rare enough to me that the DEI just hates having any cards in it but I've known it to happen.

[dwayneg]

As I recall there were instructions in the last one I set up regarding how to install...something about the order of doing things.  Looking at install manual now, says disconnect existing DEIs, power system up, connect one DEI at a time, no modules slotted, then go back in and insert modules.  It also says plug in just one at a time (removing previous) to upgrade software before making final connection, but I'm sure I didn't do that.
Also be sure the 2 or 4 DEI mode choice is correct on processor (SYSTEM/CONTROLLER/DIGITAL EXPANSION INTERFACE, then DEI MODE choose 2 or 4).

[Camoron]

The problem was the cable. We swapped the cable and it worked. Didn't try this on-site as we only had the one.