Xenarc interfering with Car Alarm

**Silvo** · 04-05-2006, 07:05 AM

hi everyone, i have a Xenarc 1020TSV. i have noticed that when the screen is powered, my car alarm doesn't work. as soon as the screen turns off, works fine.

these run on completely seperate systems. if i sit inside the car with the screen on the alarm works.

if i move around to the other side of the car (passenger) the alarm works. i know this is because the alarm module is on that side of the car.

i guess my question is... has anyone experienced this problem, what was you resolution..

or has anyone any ideas?

i'm guessing either move the alarm module to the driver's side of the car, or somehow improve its ability to receive the signal from my button.

thanks
Dan

**john1701** · 04-05-2006, 01:38 PM

same problem i have, but i got the xenarc 700tsv. When the screen is on,(has power), I have to be close to the car to use the alarm. When the screen is off, alarm works fine.
My alarm is stock, came with the car.
What i did to disable power to the screen completely, (cause the screen has standby), I put a relay on it and the relay gets power only when the pc is on.

This worked for me.
and before anyone starts, i spent months troubleshooting each part to find out it was the screen.

**dmcdlrn** · 04-05-2006, 02:12 PM

must be rf interfearing with your transmitter/receiver? Those have tuners?

**Silvo** · 04-05-2006, 03:53 PM

Originally Posted by john1701

same problem i have, but i got the xenarc 700tsv. When the screen is on,(has power), I have to be close to the car to use the alarm. When the screen is off, alarm works fine.
My alarm is stock, came with the car.
What i did to disable power to the screen completely, (cause the screen has standby), I put a relay on it and the relay gets power only when the pc is on.

This worked for me.
and before anyone starts, i spent months troubleshooting each part to find out it was the screen.

I have this, problem is that it means that as soon as you get out of the car the system needs to be off, otherwise you have to wait there.. is this right?

i run an m1-atx power supply

**Specimen** · 04-05-2006, 04:35 PM

I have the same issue with my stock Mustang alarm. But it isn't the xenarc monitor, it’s the computer and its power draw from CPU load. When the computer is shutting down, the alarm will not work at ALL. It only works if I turn the alarm on BEFORE the computer starts to shut down or until the computer is completely off. I had to replace the battery, for other reasons, and that didn't help.

My guess is that the problem is not enough power to run your car alarm. For me its my computer drawing too much power, for you guys, maybe the Xenarc Monitor is sucking up all your juice.

What else is running when the alarm is not working. Computer, amps, etc?

**Silvo** · 04-06-2006, 05:18 AM

i'll test this and see what happens

**john1701** · 04-06-2006, 05:54 AM

Originally Posted by Silvo

I have this, problem is that it means that as soon as you get out of the car the system needs to be off, otherwise you have to wait there.. is this right?

i run an m1-atx power supply

when i get out of the car, system waits 10 seconds to turn off. If I walk more than about 10 feet away from the car, while the screen is on my remote alarm does not work. Less than 10 feet alarm works. Once the system is off, everything is fine. Just cant enable, disable alarm from distance over 10 feet when the screen has power.
running opus 150ps

**JimmyFitz** · 04-06-2006, 09:04 PM

I have this problem also. I know that the Xenarc is the culprit. If I turn off the car with my carputer latched on, my Ford stock keyless entry alarm won't respond to the remote unless I get really close to where the alarm module is while pressing the buttons. If I leave the computer on but manually turn off the Xenarc screen, the remote works normally. I was using hibernate and it was a pain when getting out of the car because I had to stay nearby for 30-40 seconds while the PC shut down. Now I use STR and it is off in about 8 seconds after the key goes off. I can live with it this way.

So, now we have three Ford cars and one Nissan with this problem. And all of us have Xenarcs. Hmmmmm....

**Specimen** · 04-07-2006, 01:25 AM

good ol' Ford. I haven't tested mine too well yet. I mean I only have to chirp the alarm when I just turned off the engine and the computer is shutting down. Never done it with the computer on and such like you guys are doing. I'll do some tests this weekend to see if I can come to some conclusions.

**phc** · 04-07-2006, 01:37 AM

Originally Posted by dmcdlrn

must be rf interfearing with your transmitter/receiver? Those have tuners?

2 words, Ferrite beads.

Put them on the power wires going to the Xenarc and while you are at it, also put one on the alarm, they are really cheap. Get the clamp on type or better yet, the better way is to loop the cable thru the ferrite.

Its not uncommon for RF noise to radiate from power cables, that is why you see ferrite beads on power cables, closest to the device being powered. With switching regulators, electronic devices (like the Xenarc) have a nasty habit of radiating RF noise back thru the power input cable. Your power cable acts as an antenna, broadcasting RF and probably disrupting your alarm.

I'm not guaranteeing its going to work, but it can't hurt.

If you are in Burbank, I have a drawer full of them at work.