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I have been troubleshooting a school with 14 door magnets and cant seem to find the issue. They will be fine for days and then it shorts the 24vdc out and the fire panel has to be re-started to clear and then it is fine again. My question is, does anyone know the resistance reading of a typical door holder magnet? I have a newer style that is open when I measure it and several older ones that have a 420 ohm +/- reading.
On Tue, 24 May 2022 06:35:41 -0700 (PDT), Rick McAllister
rickm...@gmail.com> wrote:
I have been troubleshooting a school with 14 door magnets and cant seem to find the issue. They will be fine for days and then it shorts the 24vdc out and the fire panel has to be re-started to clear and then it is fine again. My question is, does anyone know the resistance reading of a typical door holder magnet? I have a newer style that is open when I measure it and several older ones that have a 420 ohm +/- reading.
That being said:
Use known-good circuit as reference. Replace anything substandard
until uniformity is achieved.
Hipot the branches for integrity.
Look for exposed areas that are subject to damage or intentional
interference - remember that this is a building full of active
gremlins.
I have been a NICET certified fire alarm technician for 30+ years now. I have worked on door holder circuits forever it seems. This one just has me baffled, since it shorts at different times when hooked up and unfortunately the Simplex panel shuts the PS down and you have to warm or cold start to get the 24volts back. I am separating it one holder at a time and waiting to see if it shorts. The school system knows they have to keep the door shut on the holder I am working on. I was just trying to see if anyone actually knows the correct impedance of one of the magnets. The cut sheets obviously tell you nothing. One of the issues is that they are all on the same circuit through the entire building.
On Tue, 24 May 2022 06:35:41 -0700 (PDT), Rick McAllister
rickmac1122@gmail.com> wrote:
I have been troubleshooting a school with 14 door magnets and cant seem to find the issue. They will be fine for days and then it shorts the 24vdc out and the fire panel has to be re-started to clear and then it is fine again. My question is, does anyone know the resistance reading of a typical door holder magnet? I have a newer style that is open when I measure it and several older ones that have a 420 ohm +/- reading.
That being said:
Use known-good circuit as reference. Replace anything substandard
until uniformity is achieved.
Hipot the branches for integrity.
Look for exposed areas that are subject to damage or intentional
interference - remember that this is a building full of active
gremlins.
RL
On Tuesday, May 24, 2022 at 11:43:47 AM UTC-4, legg wrote:
On Tue, 24 May 2022 06:35:41 -0700 (PDT), Rick McAllister
rickm...@gmail.com> wrote:
I have been troubleshooting a school with 14 door magnets and cant seem to find the issue. They will be fine for days and then it shorts the 24vdc out and the fire panel has to be re-started to clear and then it is fine again. My question is, does anyone know the resistance reading of a typical door holder magnet? I have a newer style that is open when I measure it and several older ones that have a 420 ohm +/- reading.
That being said:
Use known-good circuit as reference. Replace anything substandard
until uniformity is achieved.
Hipot the branches for integrity.
Look for exposed areas that are subject to damage or intentional
interference - remember that this is a building full of active
gremlins.
I have been a NICET certified fire alarm technician for 30+ years now. I have worked on door holder circuits forever it seems. This one just has me baffled, since it shorts at different times when hooked up and unfortunately the Simplex panel shuts the PS down and you have to warm or cold start to get the 24volts back. I am separating it one holder at a time and waiting to see if it shorts. The school system knows they have to keep the door shut on the holder I am working on. I was just trying to see if anyone actually knows the correct impedance of one of the magnets. The cut sheets obviously tell you nothing. One of the issues is that they are all on the same circuit through the entire building.
On Tuesday, May 24, 2022 at 11:43:47 AM UTC-4, legg wrote:
On Tue, 24 May 2022 06:35:41 -0700 (PDT), Rick McAllister
rickm...@gmail.com> wrote:
I have been troubleshooting a school with 14 door magnets and cant seem to find the issue. They will be fine for days and then it shorts the 24vdc out and the fire panel has to be re-started to clear and then it is fine again. My question is, does anyone know the resistance reading of a typical door holder magnet? I have a newer style that is open when I measure it and several older ones that have a 420 ohm +/- reading.
That being said:
Use known-good circuit as reference. Replace anything substandard
until uniformity is achieved.
Hipot the branches for integrity.
Look for exposed areas that are subject to damage or intentional
interference - remember that this is a building full of active
gremlins.
I have been a NICET certified fire alarm technician for 30+ years
now. I have worked on door holder circuits forever it seems. This
one just has me baffled, since it shorts at different times when
hooked up and unfortunately the Simplex panel shuts the PS down and
you have to warm or cold start to get the 24volts back. I am
separating it one holder at a time and waiting to see if it shorts.
The school system knows they have to keep the door shut on the
holder I am working on. I was just trying to see if anyone actually
knows the correct impedance of one of the magnets. The cut sheets
obviously tell you nothing. One of the issues is that they are all
on the same circuit through the entire building.
On Tuesday, May 24, 2022 at 11:43:47 AM UTC-4, legg wrote:
On Tue, 24 May 2022 06:35:41 -0700 (PDT), Rick McAllister
rickm...@gmail.com> wrote:
I have been troubleshooting a school with 14 door magnets and cant seem to find the issue. They will be fine for days and then it shorts the 24vdc out and the fire panel has to be re-started to clear and then it is fine again. My question is, does anyone know the resistance reading of a typical door holder magnet? I have a newer style that is open when I measure it and several older ones that have a 420 ohm +/- reading.
That being said:
Use known-good circuit as reference. Replace anything substandard
until uniformity is achieved.
Hipot the branches for integrity.
Look for exposed areas that are subject to damage or intentional
interference - remember that this is a building full of active
gremlins.
I have been a NICET certified fire alarm technician for 30+ years now. I have worked on door holder circuits forever it seems. This one just has me baffled, since it shorts at different times when hooked up and unfortunately the Simplex panel shuts the PS down and you have to warm or cold start to get the 24volts back. I am separating it one holder at a time and waiting to see if it shorts. The school system knows they have to keep the door shut on the holder I am working on. I was just trying to see if anyone actually knows the correct impedance of one of the magnets. The cut sheets obviously tell you nothing. One of the issues is that they are all on the same circuit through the entire building.
On 5/24/2022 12:13 PM, Rick McAllister wrote:
On Tuesday, May 24, 2022 at 11:43:47 AM UTC-4, legg wrote:
On Tue, 24 May 2022 06:35:41 -0700 (PDT), Rick McAllister
rickm...@gmail.com> wrote:
I have been troubleshooting a school with 14 door magnets and cant
seem to find the issue. They will be fine for days and then it
shorts the 24vdc out and the fire panel has to be re-started to
clear and then it is fine again. My question is, does anyone know
the resistance reading of a typical door holder magnet? I have a
newer style that is open when I measure it and several older ones
that have a 420 ohm +/- reading.
That being said:
Use known-good circuit as reference. Replace anything substandard
until uniformity is achieved.
Hipot the branches for integrity.
Look for exposed areas that are subject to damage or intentional
interference - remember that this is a building full of active
gremlins.
 I have been a NICET certified fire alarm technician for 30+ years
now. I have worked on door holder circuits forever it seems. This
one just has me baffled, since it shorts at different times when
hooked up and unfortunately the Simplex panel shuts the PS down and
you have to warm or cold start to get the 24volts back. I am
separating it one holder at a time and waiting to see if it shorts.
The school system knows they have to keep the door shut on the holder
I am working on. I was just trying to see if anyone actually knows
the correct impedance of one of the magnets. The cut sheets
obviously tell you nothing. One of the issues is that they are all
on the same circuit through the entire building.
Hi Rick,
I don\'t do Simplex panels much but it would seem to me that something on
that NAC circuit being used for the door holders is intermittently
failing. First I would suggest changing the NAC circuit to one that
may not be in use or available. I am assuming that the Door Holder
circuit is on a NAC output that is programmable to various options.
This is true of a Silent Knight Panel. Simplex...... don\'t know.
Since the Door Holders would be all in Parallel if one would fail
the others would still hold. So I would not think is would be
just one failing unless it was a dead short. If it would be
dead short then I can\'t imagine it would be intermittent.
The other thought would be when you check the voltage output
at the panel are you reading exactly 24vdc or something higher??
Like maybe 25vdc to 28vdc. That would indicate that the output may
be part of the Battery Charge Circuit. If yes, then the Backup
Batteries could be pulling the circuit down to a point where the
Door Holder can\'t hold. This is just a guess of a maybe??
Again it comes back to the DC Voltage supply that may be weak to
some degree and there is a component on the board that is failing
for some unknown reason. And moving the Door Holders to another
circuit could be the fix but not the answer.
That is about all I have at this point.
Good Luck!!
Les
The other thought would be when you check the voltage output
at the panel are you reading exactly 24vdc or something higher??
Like maybe 25vdc to 28vdc. That would indicate that the output may
be part of the Battery Charge Circuit. If yes, then the Backup
Batteries could be pulling the circuit down to a point where the
Door Holder can\'t hold. This is just a guess of a maybe??
Les