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How did my alarm code change when I never touched it



 
 
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  #1  
Old February 24th 17, 08:52 AM posted to sci.electronics.repair,alt.comp.hardware
micky
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Posts: 439
Default How did my alarm code change when I never touched it

How did my alarm code change when I never touched it?

(not a computer but it does have a digitally stored program, and solid
state memory for the settings, less than 1000 bytes, I think.)


About 9 years ago I started to install a burglar alarm, but I didn't
finish before I had to leave on my trip.

After I got home, I didn't care anymore.

I'm leaving on another trip soon and I started in on the alarm agailn.

Even thogh the trouble light is lit, It didn't need much to hook it up,
but I couldn't arm it. Pressing the default arm code just let to a
longer error-beep.

Eventually did a reset, what they call a Factory Default Main Panel.

Now the default arm code works.

I'm sure I never changed the code. My previous alarm worked for 15
years or more and I used the default code all that time, never
considered chaning it**, and I was still trying to get the thing to
work. Another reason not to change it.

So can things like this get messed up just be sitting around?. In my
basement with cinder block walls. The only source of radiation is the
30 y.o. oil furnace. That coudln't do it. A small tv in the room
too. There's a microwave upstairs.

**There are occasional burglaries around here, but none of these people
know what the default alarm code is for anything. It's not like I live
on the same street as the Vanderbilts or Morrgans.


BTW, it's funny. I wanted to see if the siren worked but the code
didnt' work to arm the alarm. The third time I tried, I noticed the
Away button. This contol panel doesn't require a code when leaving
because they figure if you got in, you're trustworthy. So I armed it.
Then I opened the door until the siren went off. Then I rmemebered I
had no code to disarm it!!. I tried the code several times, again, but
it didnt' work. I unplugged the thing, but when I plugged it in
again, it armed itself. Of course. Otherwise, power failures when the
battery is dead would disarm alarms. So I was trapped in the house.
Eventually I disconnected the control panel from the siren driver, so it
didn't make any noise the next time.
  #2  
Old February 24th 17, 09:16 AM posted to sci.electronics.repair,alt.comp.hardware
VanguardLH[_2_]
external usenet poster
 
Posts: 1,453
Default How did my alarm code change when I never touched it

micky wrote:

How did my alarm code change when I never touched it?

(not a computer but it does have a digitally stored program, and solid
state memory for the settings, less than 1000 bytes, I think.)

About 9 years ago I started to install a burglar alarm, but I didn't
finish before I had to leave on my trip.

After I got home, I didn't care anymore.

I'm leaving on another trip soon and I started in on the alarm agailn.

Even thogh the trouble light is lit, It didn't need much to hook it up,
but I couldn't arm it. Pressing the default arm code just let to a
longer error-beep.

Eventually did a reset, what they call a Factory Default Main Panel.

Now the default arm code works.

I'm sure I never changed the code. My previous alarm worked for 15
years or more and I used the default code all that time, never
considered chaning it**, and I was still trying to get the thing to
work. Another reason not to change it.

So can things like this get messed up just be sitting around?. In my
basement with cinder block walls. The only source of radiation is the
30 y.o. oil furnace. That coudln't do it. A small tv in the room
too. There's a microwave upstairs.

**There are occasional burglaries around here, but none of these people
know what the default alarm code is for anything. It's not like I live
on the same street as the Vanderbilts or Morrgans.

BTW, it's funny. I wanted to see if the siren worked but the code
didnt' work to arm the alarm. The third time I tried, I noticed the
Away button. This contol panel doesn't require a code when leaving
because they figure if you got in, you're trustworthy. So I armed it.
Then I opened the door until the siren went off. Then I rmemebered I
had no code to disarm it!!. I tried the code several times, again, but
it didnt' work. I unplugged the thing, but when I plugged it in
again, it armed itself. Of course. Otherwise, power failures when the
battery is dead would disarm alarms. So I was trapped in the house.
Eventually I disconnected the control panel from the siren driver, so it
didn't make any noise the next time.


Haven't a clue what is the hardware which you seem to deliberate omit in
your posts. Could be the code gets stored in EEPROM but I doubt it
since it would take sufficient voltage to reprogram the bits in the
chip. Could be there is a capacitor on the PCB used to hold the code.
That capacitor discharged long ago so any value stored in volatile
memory is gone. Could be a battery is used instead of a capacitor.
Just like your PC, a dead battery means the CMOS table's values (a copy
of the BIOS and where you do your tweaks, like changing a login
password) is corrupted or all values are unusable. That means the BIOS
copy of the settings get loaded into the CMOS table.

If it uses EEPROM, something is wrong with the hardware that had it lose
your stored code. If it uses a capacitor, well, those things only stay
charged for a limited time. If it uses a battery, replace it as it is
probably too old and doesn't have enough capacity (might have enough
voltage under a no-load test but cannot supply any current, even a tiny
bit, without a voltage drop).
  #3  
Old February 24th 17, 09:48 AM posted to sci.electronics.repair,alt.comp.hardware
micky
external usenet poster
 
Posts: 439
Default How did my alarm code change when I never touched it

In sci.electronics.repair, on Fri, 24 Feb 2017 02:16:25 -0600,
VanguardLH wrote:

micky wrote:

How did my alarm code change when I never touched it?

(not a computer but it does have a digitally stored program, and solid
state memory for the settings, less than 1000 bytes, I think.)

About 9 years ago I started to install a burglar alarm, but I didn't
finish before I had to leave on my trip.

After I got home, I didn't care anymore.

I'm leaving on another trip soon and I started in on the alarm agailn.

Even thogh the trouble light is lit, It didn't need much to hook it up,
but I couldn't arm it. Pressing the default arm code just let to a
longer error-beep.

Eventually did a reset, what they call a Factory Default Main Panel.

Now the default arm code works.

I'm sure I never changed the code. My previous alarm worked for 15
years or more and I used the default code all that time, never
considered chaning it**, and I was still trying to get the thing to
work. Another reason not to change it.

So can things like this get messed up just be sitting around?. In my
basement with cinder block walls. The only source of radiation is the
30 y.o. oil furnace. That coudln't do it. A small tv in the room
too. There's a microwave upstairs.


Haven't a clue what is the hardware which you seem to deliberate omit in


No, I didn't deliberately omit anything. I also didn't include it
because I can't imagine anyone here knows details about any brand of
alarm panel, who woudln't also know that they're mostly made the same.

It's a DSC Power 832. Does that actually help? There are things
about it on the web, and I dl'd some manuals before I found my paper
manuals, but I don't they give an answer.

your posts. Could be the code gets stored in EEPROM but I doubt it
since it would take sufficient voltage to reprogram the bits in the
chip. Could be there is a capacitor on the PCB used to hold the code.
That capacitor discharged long ago so any value stored in volatile
memory is gone.


But then how did resetting the panel get it back? Of course I could
ask that question about any answer, I guess.

Could be a battery is used instead of a capacitor.


I don't think there's a battery. No mention in any manual and I didn't
see one. Certainly no coin battery.

Just like your PC, a dead battery means the CMOS table's values (a copy
of the BIOS and where you do your tweaks, like changing a login
password) is corrupted or all values are unusable. That means the BIOS
copy of the settings get loaded into the CMOS table.

If it uses EEPROM, something is wrong with the hardware that had it lose
your stored code. If it uses a capacitor, well, those things only stay
charged for a limited time. If it uses a battery, replace it as it is
probably too old and doesn't have enough capacity (might have enough
voltage under a no-load test but cannot supply any current, even a tiny
bit, without a voltage drop).


  #4  
Old February 24th 17, 10:35 AM posted to sci.electronics.repair,alt.comp.hardware
VanguardLH[_2_]
external usenet poster
 
Posts: 1,453
Default How did my alarm code change when I never touched it

micky wrote:

DSC Power 832.


http://www.home-security-systems-ans...s-beeping.html

"... the alarm panel has detected one or more ´troubleˇ conditions.
These include things like battery trouble, ..."
and
"If your DSC home alarm is beeping due to this condition, the main panel
battery is low or failing."
and
"If you˙ve recently had a power outage, wait 24-48 hours after power is
restored. The battery may simply have discharged, and will recharge when
the electricity comes back on. If the beeping persists, the battery
probably needs to be replaced."

There is a link to:

http://www.home-security-systems-ans...m-battery.html

So there is a battery. Looks like you are supposed to add one. The
battery retains settings between power outages (but only however long
the battery can provide power).

  #5  
Old February 24th 17, 08:00 PM posted to sci.electronics.repair,alt.comp.hardware
micky
external usenet poster
 
Posts: 439
Default How did my alarm code change when I never touched it

In sci.electronics.repair, on Fri, 24 Feb 2017 03:35:25 -0600,
VanguardLH wrote:

micky wrote:

DSC Power 832.


http://www.home-security-systems-ans...s-beeping.html

"... the alarm panel has detected one or more ´troubleˇ conditions.
These include things like battery trouble, ..."
and
"If your DSC home alarm is beeping due to this condition, the main panel
battery is low or failing."
and
"If you˙ve recently had a power outage, wait 24-48 hours after power is
restored. The battery may simply have discharged, and will recharge when
the electricity comes back on. If the beeping persists, the battery
probably needs to be replaced."

There is a link to:

http://www.home-security-systems-ans...m-battery.html

So there is a battery. Looks like you are supposed to add one. The
battery retains settings between power outages (but only however long
the battery can provide power).


Oh, that battery. That's meant to power the panel and the siren and
the dialer if there's a power failure. It's not meant to retain things
in memory except user-decided things like the time and which zones are
excluded. It's not meant to retain defaults. That's what makes them
defaults. . When the board comes from the factory, it's not connected
to the battery and it stays that way for weeks or months until someone
sets up the whole system**, but the contol panel doesn't forget what the
default alarm code is. **In fact, my friend who owns an alarm
company (but who is not intereted in questions like the one in my OP)
who is normally a stickler for things, agreed that I didnt' have to have
a battery to run the alarm, since outages are so rare here.

I had looked on the DSC site but the manuals I found need needed
permission to be downloaded. I have them in print but to use Find, it
helps to have digital copies. Part of your url above is written
specifically for DSC and it also linked to a place where I could dl the
exact manual that I already have. Thanks a lot
  #6  
Old February 24th 17, 11:43 PM posted to sci.electronics.repair,alt.comp.hardware
VanguardLH[_2_]
external usenet poster
 
Posts: 1,453
Default How did my alarm code change when I never touched it

micky wrote:

Oh, that battery. That's meant to power the panel and the siren and
the dialer if there's a power failure. It's not meant to retain things
in memory except user-decided things like the time and which zones are
excluded.


You cannot program anything without power - unless this panel has dip,
toggle, or other types of switches to hardwire in that "data".

Another possibility (already mentioned) is the use of EEPROM; however,
there would need to exist power to raise the voltage to burn in the new
values. Are there EEPROMs on the PCB?

How can you enter and save a security code without there being power?
Electronically it is possible when there exists power that will be saved
after power is lost (battery, capacitor, EEPROM) - but you still need
power during that operation. From the images I found online, there are
no switches on the PCB for that device, just a 4-pin header (S1) where
you use jumpers:

http://s3.amazonaws.com/f01.justansw...9_12.09.16.jpg

Ah, finally found something:

http://www.alarmsbc.com/dscpwr.htm#832
EEPROM memory
- will not lose programming or system status on complete AC and
battery failure

I couldn't tell from the photos I found online if there was an EEPROM,
plus the pics showed the component side of the PCB so I couldn't tell
what, if anything, was on the other side. I cannot guarantee the above
URL specifies only the 832 since the 5010 replaced it (and they might be
showing the specs for the 5010).

An EEPROM still requires power to program it. EEPROM = electrically
erasable programmable read-only memory. You need power to erase or
program values into its storage. Some EEPROMs have a built-in charge
pump to attain the higher voltage while others require external
circuitry to apply the higher voltage. But the EEPROM requires power to
program it. You said you entered in a new access code. That meant you
must have connected it to power.

The values should stay in the EEPROM unless you did something by
accident, like after plugging in the A/C power adapter. EEPROMs have a
limited number of write cycles but I doubt you have programmed it a
million times.

https://en.wikipedia.org/wiki/EEPROM#Failure_modes
(another possibility is a bad, weak, or leaky EEPROM)

There is mention of a maximum retention time of 10 years for values
stored in EEPROMs. How long has this one been sitting idle and
unconnected from power? *Oh oh*, "About 9 years ago I started to
install a burglar alarm". I missed than in reading your original post.
So you waited too long to refresh the EEPROM and the pics of the PCB
don't exude an impression that this one has auto-refresh circuitry but
then that would require power, too, and refreshing means more writes (so
the EEPROM could get consumed by frequent refreshing).

The AlarmsBC web site has links to free manuals at:

http://www.alarmsbc.com/manuals.htm

I clicked on "DSC" and found 2 manuals for the 832 (5010) depending on
the version of the unit. I looked at version 1 of the manual. Page 7
says how to program the access codes. No mention of enabling a switch
or jumpering of the S1 header to program the EEPROM. However, there
must be power available when using the device, even to program the
access codes. There is no troubleshooting section in their manual.

Looks like the *oh oh* problem is that you expected the EEPROM without
refresh to retain its values forever. EEPROMs leak the charges
(hopefully slowly) but those charges do dissipate over time. 9 years is
too close to the 10-year claim for retention (and who knows what quality
of EEPROMs went into this device).

[E]EPROMs have a shelf life regarding retention. They have a finite
data retention time. DSC probably didn't expect something laying around
for a decade to still need to use the same access code. Who'd remember
that after a decade's absence? They begin to forget their data after
10-15 years. Yours was on the shy side of that. Mask ROMs don't have
that problem because the values are etched (burned) permanently into the
chip at production time. There are SuperFlash EEPROMs that claim data
retention for 20-100 years (but that's still finite); see
http://www.sst.com/technology/sst-su...eneration-esf1.
That was introduced back in 1993. Don't know if DSC used any. PC mobos
adopted them.

After 10 years of absence (no refresh) with or without power is too long
to expect no degradation (data corruption or loss) for EEPROMs.
 




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