Re: ademco DSC staple short keypad drop

["Frank Olson" <feolson@xxxxxxxxxx>]

"autonut843" <hmjunk31415@xxxxxxxxxxx> wrote in message
news:1119189272.754327.136820@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Hi,
> I was just searching for posts about ademco products and saw a post
> where someone mentioned
> "I have seen mother boards smoke because of staples through keypad
> drops."
> I was always wondering what would happen if a burglar broke in and,
> instead of trying to find the control panel to disable the alarm, just
> ripped the keypad off the wall and shorted the wires together while the
> entry delay was beeping at them telling them to disarm.  I've never
> wanted to risk toasting the control board to try it but while wiring
> them up it seemed like sending the 12V out to the keypad was risky if
> they didn't somehow isolate that 12V from the main 12V power.  Does
> anybody know if Ademco panels have this achilles heel?  Surely Ademco
> put a resistor or something on the "red keypad pwr (+)" terminal so
> shorting it to the "Black Keypad Ground (-)" would not bring down the
> entire panel.  Anybody have a spare panel they can try it on?  Is there
> a brand of alarm that does not have this problem?  Thanks.  My email is
> a spam magnet so I don't check it any more, please don't reply to it.
>

On older systems you'd wind up shorting "aux" or "keypad" power which would
blow the fuse.  The panel would continue to count down the entry delay and
then (with no keypad present to disarm the system) would go into alarm.  On
newer panels you'd "open" the PTC which wouldn't restore again until the
short was removed (with the same resulting alarm).  The only time I've ever
seen a panel "smoke" (when there's been a short on the aux power terminals)
is when some "nimrod technician" (in the employ of a competitor) didn't have
the right fuse to replace the one on the board and wrapped the blown one
with foil from a cigarette pack.  I have also seen the result of unfused
transformers "smoking up" when there's a sudden short on the secondary...