Complicated Napco MA2600 Internals Issue

It could be time for you and Paul to check out some new headphones.

The MA 2600 is a very old panel. Many early Napco panels had RF issues. Early MA-800 panels could pick up nearby AM radio stations. MA 1000 series were a pain to many HAM operators as well. Any panel with a polling loop or analog loop can generate some nasty RF in certain environments. Even if you weren't having RF issues I'd suggest upgrading from the MA 2600 since it is beyond legacy status.

I don't know how your system is programed but if it isn't programed to alert on AC fail, just get a power supply with a back up battery and power the system through the battery terminals only. No AC to the panel at all. Do you have access to the dealer programing? If you do, and the system is giving you an AC fail signal, I think you can program it to not alert to an AC power failure. I'd have to check the manual to be sure, however. Let me know if you have access.

If not, some panels can be fooled into thinking that AC is applied just by applying 12 VDC to one of the AC terminals. I don't remember if the 2600 can do this or not. You may have to follow some circuitry on the board to find out if they're using a bridge rectifier or not or which of the AC terminals to use.

Jim,

That's a great idea and I do have full access to the programming.

Thanks!!!

-Katie

Try

2 use .01 capacitors in parallel, on each of the alarm zone negative terminals and tie to battery ground. This will bleed off any AC from the zone cables and block the DC to battery ground. Do the same with keypad terminals. This will help nullify induced AC noise from nearby

This has worked for me for years. Alarm companies have sent me to their troublesome panels. However, I never did tell them what my solution was - aka guaranteed income !

gqc

Katie Wasserman wrote:

Katie,

If you can re-run your keypad cables, use shielded cable to minimize RF leakage from the databus. You may use shielded cable with Napco, Honeywell, and Bosch's data loops and keypad data cables. Consult the ARRL's RF Handbook

Russ, Thanks for the suggestion and ARRL pointer but rewiring isn't an easy option.

But I did try GQC's idea of using bypass capacitors on all the lines and that made a huge different, especially on the keypad lines, noise dropped by almost 15db. All of the noise is/was coming from the alarm wiring, running running on the battery alone gives the same noise level, so the AC line choke wasn't needed.

Jim, your idea of running off the battery power feed only doesn't work. The system needs the AC power to start up or it triggers the alarm, there seems to be no way around this. Putting in a fake battery using a capacitor discharging through a diode and charging through a parallel resistor didn't work either. The system does a 1 second test using the battery about 1 minute after AC startup, that's how it determines if the battery is good. After that point it seems to do a battery check each time the system is armed. So you really do need to have a real battery in there (or a giant capacitor) to make this alarm function.

Thanks to everyone for you help on this.

Did you try to apply 12VDC to one of the AC terminals?

I've got a few Napco and other manufacturers systems running on 12VDC only on boat alarms. Never used a 2600 for this application though. Applying 12VDC to one of the AC terminals has worked for me as far as fooling the system into thinking AC was applied. When the power is removed from these units and restored, there is no indication of AC power loss or low battery. I have no idea whether running it this way will reduce the RF emissions.

My original suggestion to you about powering the unit this way, was following up on your method of wanting to shut the system down while you were transmitting. I still didn't check the installation instructions but did you investigate whether you can program the panel to ignore an AC power loss?

Another thought occured to me also, regarding the "sequencing" of the application of AC and DC. If I remember correctly ( ie. I could be wrong) when you power up the panel, there is a momentary "blip" on the output of the siren. This might mean that the Aux relays are being momentarily "pulsed" too. You may be able to utilize this momentary closure of the Aux contacts to pic another relay that would lock in. This relays contacts hooked in series with the positive lead of the battery, could then apply the DC voltage a split second after AC is applied.