Hello all,

This is an electronic question, it is related to a security panel and the
End Of Line Resistor. For those that do not know the EOLR is a resistor
that in placed within the protected loop to provide a small amount of
current to flow and thus supervises the loop. If the loop is cut it is an
alarm, if the loop is shorted it could be an alarm or trouble depending upon
the status of the panel. Enough background.

Today I had a strange occurrence with a EOLR. The system was not reporting
the zone open even though I was holding the door open and looking at the
keypad. After a period of troubleshooting found that the 3.74k resistor was
now 5.86k. Replaced with new and all is well. This is the second time in 17
years that this has happened to me. Very Strange???
I wonder what would make it change in this way. Any thought???

Just looking for opinions on this. The environment was a clean office,
normal temps, humidity very comfortable. No signs of overheating of the
resistor, no corrosion present. All looked as it did when I installed about
4 years ago except for the very high value.

Thanks in advance.

Les

If the door was open how did the panel see the resistor ? the resistor must
of been before the door switch .because with the door open (door switch not
made or shorted)
the panel can not see the resistor . It is only(resistor) used for
supervision.

"Ross Herbert" wrote in message
news
On Sun, 19 Feb 2006 12:55:16 -0500, "ABLE_1"
wrote:

Hello all,

This is an electronic question, it is related to a security panel and the
End Of Line Resistor. For those that do not know the EOLR is a resistor
that in placed within the protected loop to provide a small amount of
current to flow and thus supervises the loop. If the loop is cut it is an
alarm, if the loop is shorted it could be an alarm or trouble depending
upon
the status of the panel. Enough background.

Today I had a strange occurrence with a EOLR. The system was not reporting
the zone open even though I was holding the door open and looking at the
keypad. After a period of troubleshooting found that the 3.74k resistor
was
now 5.86k. Replaced with new and all is well. This is the second time in
17
years that this has happened to me. Very Strange???
I wonder what would make it change in this way. Any thought???

Just looking for opinions on this. The environment was a clean office,
normal temps, humidity very comfortable. No signs of overheating of the
resistor, no corrosion present. All looked as it did when I installed
about
4 years ago except for the very high value.

Thanks in advance.

Les


Any idea who manufactured the original resistor? Could be a junk
brand...

The only problem I have had was with 0.6W metal film resistors going
high (Beyschlag now part of Vishay) when operating directly on 240Vac
circuitry. Even an identical replacement failed some months later.
They didn't seem to like it for some reason. After finally replacing
with a high quality carbon film type it worked fine and never failed
again.

I can't imagine that your resistor would be operating at 240Vac levels
so I can't surmise what caused it to go high.

"ABLE_1" wrote in message
...
Hello all,

This is an electronic question, it is related to a security panel and the
End Of Line Resistor. For those that do not know the EOLR is a resistor
that in placed within the protected loop to provide a small amount of
current to flow and thus supervises the loop. If the loop is cut it is an
alarm, if the loop is shorted it could be an alarm or trouble depending
upon
the status of the panel. Enough background.

Today I had a strange occurrence with a EOLR. The system was not reporting
the zone open even though I was holding the door open and looking at the
keypad. After a period of troubleshooting found that the 3.74k resistor
was
now 5.86k. Replaced with new and all is well. This is the second time in
17
years that this has happened to me. Very Strange???
I wonder what would make it change in this way. Any thought???


when in doubt, blame lightning.


Just looking for opinions on this. The environment was a clean office,
normal temps, humidity very comfortable. No signs of overheating of the
resistor, no corrosion present. All looked as it did when I installed
about
4 years ago except for the very high value.

Thanks in advance.

Les


the quality of basic components seemes to be in a decline these days.

"ABLE_1" bravely wrote to "All" (19 Feb 06 12:55:16)
--- on the heady topic of "Resistor Value Change"

AB From: "ABLE_1"
AB Xref: core-easynews sci.electronics.repair:358702

AB Hello all,

AB This is an electronic question, it is related to a security panel and
AB the End Of Line Resistor. For those that do not know the EOLR is a
AB resistor that in placed within the protected loop to provide a small
AB amount of current to flow and thus supervises the loop. If the loop
AB is cut it is an alarm, if the loop is shorted it could be an alarm or
AB trouble depending upon the status of the panel. Enough background.

AB Today I had a strange occurrence with a EOLR. The system was not
AB reporting the zone open even though I was holding the door open and
AB looking at the keypad. After a period of troubleshooting found that the
AB 3.74k resistor was now 5.86k. Replaced with new and all is well. This
AB is the second time in 17 years that this has happened to me. Very
AB Strange??? I wonder what would make it change in this way. Any
AB thought???
AB Just looking for opinions on this. The environment was a clean
AB office, normal temps, humidity very comfortable. No signs of
AB overheating of the resistor, no corrosion present. All looked as it
AB did when I installed about 4 years ago except for the very high value.

AB Thanks in advance.

AB Les


Perhaps the damage to the film resistor is due to static discharge by
people walking up or from their clothes or a nearby copy machine. Try
protecting the line with a small spark gap or, if the voltage is low,
a small neon tube across that resistor.

A*s*i*m*o*v

.... Integrated Circuit (n): a device used to protect fuses.

The resistor was in series with the door switch. As to the operation of the
zone all is now well with the proper resistor so that is of lesser
importance.

My main question is to what would cause a resistor to change value to this
level with out any noticeable physical changes such as heat or something???

It does seem to be a strange question I know and maybe one that will never
be answered. I was just looking for some opinions or ideas as to why.

Thanks



If the door was open how did the panel see the resistor ? the resistor
must of been before the door switch .because with the door open (door
switch not made or shorted)
the panel can not see the resistor . It is only(resistor) used for
supervision.

"Ross Herbert" wrote in message
news
On Sun, 19 Feb 2006 12:55:16 -0500, "ABLE_1"
wrote:

Hello all,

This is an electronic question, it is related to a security panel and the
End Of Line Resistor. For those that do not know the EOLR is a resistor
that in placed within the protected loop to provide a small amount of
current to flow and thus supervises the loop. If the loop is cut it is
an
alarm, if the loop is shorted it could be an alarm or trouble depending
upon
the status of the panel. Enough background.

Today I had a strange occurrence with a EOLR. The system was not
reporting
the zone open even though I was holding the door open and looking at the
keypad. After a period of troubleshooting found that the 3.74k resistor
was
now 5.86k. Replaced with new and all is well. This is the second time in
17
years that this has happened to me. Very Strange???
I wonder what would make it change in this way. Any thought???

Just looking for opinions on this. The environment was a clean office,
normal temps, humidity very comfortable. No signs of overheating of the
resistor, no corrosion present. All looked as it did when I installed
about
4 years ago except for the very high value.

Thanks in advance.

Les


Any idea who manufactured the original resistor? Could be a junk
brand...

The only problem I have had was with 0.6W metal film resistors going
high (Beyschlag now part of Vishay) when operating directly on 240Vac
circuitry. Even an identical replacement failed some months later.
They didn't seem to like it for some reason. After finally replacing
with a high quality carbon film type it worked fine and never failed
again.

I can't imagine that your resistor would be operating at 240Vac levels
so I can't surmise what caused it to go high.

In article ,
ABLE_1 wrote:
My main question is to what would cause a resistor to change value to
this level with out any noticeable physical changes such as heat or
something???

It does seem to be a strange question I know and maybe one that will
never be answered. I was just looking for some opinions or ideas as to
why.

My 'stock' of resistors is based on 0.6w metal film types and I've never
known this to happen.

--
*I don't know what your problem is, but I'll bet it's hard to pronounce

Dave Plowman London SW
To e-mail, change noise into sound.

On Sun, 19 Feb 2006 12:55:16 -0500, "ABLE_1"
put finger to keyboard and composed:

Today I had a strange occurrence with a EOLR. The system was not reporting
the zone open even though I was holding the door open and looking at the
keypad. After a period of troubleshooting found that the 3.74k resistor was
now 5.86k. Replaced with new and all is well. This is the second time in 17
years that this has happened to me. Very Strange???
I wonder what would make it change in this way. Any thought???

I had this same problem in several units of one particular monitor. In
each case a 1/4W carbon resistor had gone high in value. Dissipation
was not an issue as the resistor was operating well within its design
limits, and the circuit had no other faults. The operating voltage was
only 5V, ie TTL.

I've also experienced open resistors in resistor packs, again at TTL
voltage levels.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Franc,

So then the guess would be the resistor was bad to start and then when
exposed to some current flow it just went HI??? That is a plausible answer
then. Still very strange indeed. One just never knows some days.

Thanks for the input.

Les

"Franc Zabkar" wrote in message
...

I had this same problem in several units of one particular monitor. In
each case a 1/4W carbon resistor had gone high in value. Dissipation
was not an issue as the resistor was operating well within its design
limits, and the circuit had no other faults. The operating voltage was
only 5V, ie TTL.

I've also experienced open resistors in resistor packs, again at TTL
voltage levels.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.