I came home from work today and noticed an "output expander lost comm" message displaying on my keypad. At first I thought it was a momentary hiccup in the databus, and so I ignored the message. However, when I checked a little later in the evening, the message remained. So I went and did some more investigating. I checked the log file and indeed there was an event that registered: Expansion Module Trouble, Output Exp. 3. I opened up the can that held this board and the board looked dead - no blinking light. Unfortunately, this was an important output board as it controlled the relay that activates the synchronized sounding (RRS-MOD) for my smoke alarms. Fortunately, I had an extra M1XOVR board on hand, so I popped the dead one out (the removable terminal blocks made that easy!) and inserted the new one in, making sure my termination jumper and address dip switch settings were the same. Then I re-enrolled everything, but the board registered only after several attempts at the process (the system didn't recognize the board until I finally removed and reinserted the databus wiring...). Now everything seems back to normal.
Upon closer inspection of the dead board, I found a burnt integrated circuit chip labeled "U5" on the back side towards the upper left of the board, and directly on the flip side of what looks like two resisters labeled "D24" and "D23". The board is mounted on those plastic pushpins, so it is isolated from the can enclosure- ruling out shorting to the enclosure.
Here's a photo:
Now, does anyone know why something like this happened??
Upon closer inspection of the dead board, I found a burnt integrated circuit chip labeled "U5" on the back side towards the upper left of the board, and directly on the flip side of what looks like two resisters labeled "D24" and "D23". The board is mounted on those plastic pushpins, so it is isolated from the can enclosure- ruling out shorting to the enclosure.
Here's a photo:
Now, does anyone know why something like this happened??