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.