Over the past 2ish months we've had about 6 ALCs go band on one of our shelves. It is isolated to this one self. Only the ALCs are going bad and the DLCs are good. Every attempt to do DISC and ENLCs fail. Also if you move the card to another slot and equip it, it’s still bad. Reseating it does nothing, not even the 3 red flashes. Once you pop a new card in the slot its up and working. It’s a Option 81C with 7 superloops and most of them have 2 shelves. I was thinking power supply for that shelf or maybe ground but wouldn’t that affect the whole system and not just an isolated shelf? Any ideas?

Also I dont know if this is related but about 2 weeks ago we have about 9ish 3903s go bad one night. If you change the TN still bad, just had to replace the phone.

Your Idea of the Power Supply for the Shelf sounds the most likely candidate. I've had a few cases where the Power Supply unit has affected only FALC cards, as the FALC card uses voltages not used by other Cards.

Thanks for the advice MossEng. I think I'm going to swap the PS to that shelf. Do I need to take down the loop when I do that and is it hot swappable?

Interesting you are having this problem - I am having a similar thing only the ring gen card keeps dying...? I was wondering if it may be the PS for that shelf as well. Also was wondering how to go about changing it out?

Power supply is not hot swappable. Disable the controller (LD 32 DSXP x) then power off the shelf. Replace the PS and power it back up. Then enable the controller (LD 32 ENXP x).

Bad69cat, if you're having multiple ring generators go out in the same shelf, you might have an analog card in that shelf be the cause. We had the same issue last week. Swapped the generator, no go. Swapped system monitor, no go. Unseated one analog card at a time and when the faulty card was removed, the generator lit up.

Didn't mean to hijack - but sounded like same problems. I did swap the ring gen - succesfull for a few weeks....some good thoughts though. Thanks telebub! I'll dig deeper