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Old 06-04-2014, 10:26 AM
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Default CDM Pin #4 External Alarm Issues.

Hey guys I'm having a very frustrating inconsistant problem with ouR station alarms. I'm using a CDM 1250 and we tone using quick call II.

I have a cdm1250 mounted to a power supply and a relay attached to the side of the radio. The realy is powered off the power supply to pin 85, pin 30 is grounded by pin #7 on the radio 86 is my trigger coming off the radio, And my station lights ground is on 87 and + for the lights is on 85.

THE PROBLEM
I have and problems with some random stations not turning on the lights when the radio recieves tones. I can give 86 ground by using my power probe and the lights come on just like they are suppose to, but yet when the radio recieves tones pin #4 is not giving the relay ground.

WHAT I HAVE CHECKED SO FAR.
I have checked accessory pins in the cps over and over again, all programable pins are set to "Null" except #4 I have that set to "external alarm" am I missing another setting? maybe like a delay or something? I have checked the signaling tab and everything on that end is right because the radio does light up when a call is recieved.

The frustrating thing is it happens on a station everyonce in a while. Yesterday I took 2 brand new 1250's out of the box and neither worked. I'm stumped PLEASE HELP.
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Old 06-04-2014, 3:31 PM
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Relay has too low coil resistance?

Only the two coil should be connected to the radio.
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Old 06-09-2014, 1:38 PM
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I checked the relay and its at 9.2 ohms, is that too much resistance for the radio to operate?
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Old 06-09-2014, 6:25 PM
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Quote:
Originally Posted by Radio_Shop View Post
I checked the relay and its at 9.2 ohms, is that too much resistance for the radio to operate?
Sounds like you are trying to use a starter relay.......... 9.2 oms coil resistance is way too low. The radio will choke on that..
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Old 06-09-2014, 8:26 PM
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Here's a device that will work for radio activated alarms. Go to elkproducts.com and look up the ELK-924 Sensitive Relay. I have built many siren and light timer control systems for fire/rescue stations using these and other components available from them. They will readily accept the alarm output from any CDM/MaxTrac/Radius 16 pin connectors and require only a 1.2 mA trigger to activate. There are 2 optically isolated 10 amp SPDT relays mounted on a board and configurable for + or - trigger, and are powered by the radio's 12 volt power supply.

This item is only a few bucks - probably around 10-12 bucks shipped. They are in the alarm components manufacturing business, are located in the US, and have numerous components and items useful to the two-way radio business, including timers, relay boards, board mounted audio amps, and other things.
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Old 06-10-2014, 12:41 AM
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I use the Elk 924 and other products from Elk for a lot of things.

The CDM cannot sink more than about 80ma reliably. You run the risk of it either not working or destroying the gate in the device driving the pin.
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Old 06-10-2014, 8:28 AM
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hey guys thanks for all the info. I also ran across elk-912 would this also work?
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Old 06-10-2014, 8:28 AM
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ELK-912 Compact Relay module, 12 Volt DC coil
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Old 06-10-2014, 9:07 AM
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Yes, you could use that model as its 35 mA coil load is within the capability of the CDM alarm output, but for the reason com501 posted I would still choose the ELK-924. The ELK-924's 1.2 mA trigger load would almost be transparent to the CDM, and since the CDM alarm output is electronic instead of a mechanical point closure, the optical isolation from the relay's coil loads is highly beneficial to component reliability and longevity on both sides. Besides, by adding ELK timers to the scheme, one relay can activate a siren timer circuit, and the other relay output can be used to trigger a light timer, thus providing more isolation.

Last edited by CCHLLM; 06-10-2014 at 9:36 AM..
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Old 06-10-2014, 9:19 AM
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Quote:
Originally Posted by CCHLLM View Post
Yes, you could use that model as it's only 35 mA coil load, but for the reason com501 posted I would still choose the ELK-924. The ELK-924's 1.2 mA trigger load would almost be transparent to the CDM, and the isolation from the coil load is highly beneficial to component reliability and longevity.
Roger i'll stick with the 924 thanks guys!
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Old 06-10-2014, 4:45 PM
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Quote:
Originally Posted by Radio_Shop View Post
The ELK-912 will work just fine on the CDM series radios. Has only a 30 MA draw that IS within the radio's capability and specs.
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Old 06-10-2014, 9:43 PM
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Just to add something for those that still may be using a heavier duty / automotive relay; use a diode around 85 and 86. This will reduce / eliminate the flyback (voltage spike) from the coil of the relay that can smoke the smaller transistor arrays that drive those outputs.
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Old 06-11-2014, 11:07 PM
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Quote:
Originally Posted by Brandon_K View Post
Just to add something for those that still may be using a heavier duty / automotive relay; use a diode around 85 and 86. This will reduce / eliminate the flyback (voltage spike) from the coil of the relay that can smoke the smaller transistor arrays that drive those outputs.
The relay you describe has too low coil resistance to work properly.
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Old 06-13-2014, 1:36 AM
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You should be buying the Bosch ones, in gray, that have the diode already installed.
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