Replacing alarm: EOL resistor question

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Old 08-22-16, 11:57 PM
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Arrow Replacing alarm: EOL resistor question

Hello there. This is my first post here.

I have an Acron AV-8000 alarm at home that I installed in 1988 or thereabouts. It has worked flawlessly and not given out one false alarm, nor have any of the switches or PIRs failed.

This alarm is pretty long in the tooth and there is smoke reisidue inside the top of the box, meaning some electrical component released the magic smoke. My garage keypad is also getting hard to make connections with button pushes. I want to add a hefty siren and strobe, which will require upping the available 12VDC, and throwing money at this wounded dinosaur doesn't make sense.

Soooooo, I was thinking of replacing it with a VISTA 20P/6160 keypads and use the existing wired sensors.

Here is the question: The EOL resistors on the Acron are 2.2K, while the 20P uses 2K resistors. It would be a royal pain to change out those resistors because I really buried some of those sensors. Could I get away with leaving the old resistors in place? Would the alarm know? Would adding a 200 ohm resistor in series at the box fix things?

Thanks

PS. I'm gonna miss those LEDs on each zone keypads. One quick glance from anywhere in my hallway, and I can tell which doors/windows are open, or where there is movement in the house.
 
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Old 08-23-16, 02:43 AM
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Welcome to the forums.

Adding a 200 ohm resistor in series with a 2.2k ohm resistor yields 2.4k ohm.

You're going to need to change them at the contacts.
 
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Old 08-23-16, 09:12 AM
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Oh duh! That is what I get for posting right before going to bed. I got the EOL resistors mixed up.

I just checked all my reed switches, and only 2 will be easy to change out the resistor. Man, I was good at patching drywall back in the day. Those things look like they were put in when the house was just framed. Hacking up door jambs/drywall is a non starter.

Would a pull down resistor in parallel work?

The alternative is to add 12v to my existing setup so as not to add load to the maybe compromised (remember the smoke?) rectifier/voltage regulator. I would be over the allowed 2 amps bell load anyway. So it looks like I would need a 40VA wall wart, a 2.5 amp DC converter w/battery charger, a relay, and another battery to power my bell loads. Oh, and probably another box to house it all in if I can't shoehorn all that into the existing one. The plan would be to put all but one siren on the new power so as not to stress the existing system. The good news is that we get to keep our beloved Digi-Key LED keypad that tells us with a glance from 10 feet away which zone is being tripped.

With the recent prison early releases and law changes (CA Prop 47), break ins have shot up. My goal is to make it painful to be inside and wake the dead outside when the alarm is triggered.
 

Last edited by Idahobound; 08-23-16 at 09:44 AM.
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Old 08-23-16, 08:08 PM
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Putting a resistor in parallel to pull the overall resistance down to 2k would work. That extra 200 ohms would give you no end of grief in the form of random false trips.
 
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Old 08-23-16, 09:32 PM
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Thank you for the reply. Any idea what value to use to get to 2K? I have the full range of 1% resistors, but they are 0603 SMDs. A lot of good they will do.
 
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Old 08-23-16, 10:14 PM
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I think Mr Ron meant to say....

Putting a resistor in parallel to pull the overall resistance down to 2k would work BUT that extra 200 ohms would give you no end of grief in the form of random false trips.


The parallel resistance needed to be added would be 22k. (if you wanted to play)
22k in parallel with 2.2k = 2k
 
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Old 08-23-16, 11:16 PM
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Thank you. Has this (adding 22K in parallel at the box to get 2K out of an old install) been done successfully before? Surely, I can't be the first person to upgrade a 2.2K system to a 2K one with buried devices that can't reasonably be upgraded at the contacts.
 
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Old 08-23-16, 11:27 PM
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I don't know. It's not something that I as an installer would ever do.
 
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Old 08-24-16, 03:12 AM
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It's not something that a pro installer would do, but in terms of the simple math of how resistors work, it would do the trick.
 
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Old 08-26-16, 03:15 PM
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Thank you for the responses. We're going to be traveling a lot and I'm having trouble with adding bell loads to the old Acron alarm that released SO MUCH SMOKE. I also like the idea of self monitoring, so we can tell while out of town if something is amiss.

Soooooo I've decided to just replace the whole damn thing.

The house is already hard wired. Most of the EOL resistors can be replaced. Those that can't, I'll try the 22K parallel resistor thing at the panel. I have existing sirens, but recently bought more plus a strobe (that I would like to run longer than the bells). I also bought a new 7AH battery.

Here is my shopping list:

Vista 20P
6160RF (just in case I want to add wireless devices).
6160
EVL-4 (for self monitoring)

If I go over 2 amps on the bell, I'll add a 2.5A power supply, a battery, a relay, and maybe another wall wart. See question below.

Question 1: Can I use a 40VA wall wart to power BOTH the 20P, and a 2.5A power supply? Looks like my bell load is going over 2A. No room for second wall wart unless I add a box or go power strip.

Question 2: I would like to run the strobe after the bells time out. How is this accomplished? Do I need to add a relay or something? Ya, I know. RTFM.

We are only going to be in this house another two years, so we don't need anything fancy. The next house will be on some land where it snows, so I'll need to do more monitoring. Plus, I just dig gizmos in general.

Still gonna miss those LEDs on that Digi-Key pad. Wish there was a way to keep them.

Edit: I think I know where that smoke came from. My Fluke shows 50 or so Hz on the DC output. Looks like I fried one of those caps in the rectifier. If I still had the scope, I would know for sure.
 

Last edited by Idahobound; 08-26-16 at 05:22 PM.
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Old 08-30-16, 09:37 AM
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You will need separate transformers for the panel and auxiliary power supply.

Yes, you'll need to use a 4204 relay if you want the strobe to continue to run after the normal bell time-out so that it's programmed to activate on alarm and stop on disarm (I assume that's what you'd want).
 
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Old 08-30-16, 12:27 PM
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Thank you. I'm getting closer to a decision between the Vista 20P and the L7000.
 
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