Shock sensor prablem (aritech)

[Guest cdaly]

I'm having trouble with a self-installed aritech alarm system where one shock sensor goes bad on a regular basis.

The alarm board is IIRC a CS350 (6 zones, remote keypad), the sensors are aritech reed/shock combo sensors (can't remember the model number). On one door, the shock sensor module goes bad on a regular basis. It's on its third sensor at this point and I've had to bypass that one. It goes like this:

• install new shock sensor, all is fine
  
• after a few months, at setting time, the zone shows open
  
• A thump on the door settles the sensor and the alarm sets
  
• The level of thumping required gets progressively worse
  
• Finally, the sensor won't reset and has to be inhibited
  

Replacing the shock sensor module (into the original body with original reed switch) fixes everything for a time. If I remove the unit cover and dismount the shock sensor (leaving it connected) and leave it hanging, it resets. Once I remount it where it should sit (the word 'aritech' on the front should be horizontal according to the manual), it goes open circuit again.

The sensor is mounted on the inner edge of the door with the magnet on the door frame. The magnet is pretty close to the shock sensor. The wiring to the sensor is arranged so it does not kink when the door closes / opens. This sensor is the end of line on this (three wire) zone and has a 1k resistor in the tamper line and a 1k across the sensor contacts. The wiring is an extension from the original end of line in the room next door (this door was fitted after the alarm wiring was installed). The door has a weather seal close to the sensor and there appears to be no sign of moisture in the sensor casing.

I've done all of the fitting myself and am happy that it's correctly done.

Is there anything I can do to test the sensor, my wiring, the magnet placement etc.?

I have the manual that came with the alarm board and the bit that details the three-wire tamper circuit setup.

Thanks for any help you might give...

Conor

[Guest cdaly]

moisture ingess - check the PCB for corrosion.

There appears to be no PCB in this sensor unless it's within the (sealed as far as I can tell) shock sensor module itself. There's no sign of dulling on any of the exposed wiring or contacts within the sensor so I'm inclined to think there's not a moisture problem there. That said, it's probably in the coldest part of the kitchen.

install problem - the shock sensor should not be on the movable part of the door, it may be that the action of the door is stressing the cable and causing the PCB to twist slightly, which can cause the lacqor to crack or create a dry joint, especially with SMT built boards.

I was pretty much aware of the cable twisting / creasing risk so I set it up much like the cables run into a car door. Cable is stapled to the frame and to the door with about 10cm of cable in a loop with only about 4cm separating the fixed bits. There's a few staples between sensor and cable loop so twisting seems unlikely.

IIRC, I mounted the sensor on the door rather than frame 'cos the weather strip frame would get in the way. I think there was an element of "the door frame won't see enough of shock vibration to trigger the sensor" too. I'll have to revisit that. Are these sensors OK to mount facing down?

or shock of the door being slammed, causing similar problems to those above.

Now, this looks more like a possibility esp with the kids...

Is the magnet placement likely to be a problem? If it's too near the shock module?

Thanks for that...

[Brian c]

Those are mechanical devices and have no circuitry on board.

IIRC, it's something like a ballbearing sitting on 4 pins, when the ball moves (when hit) it opens the circuit.

It seems you can get them all to work for a time, then you have problems. That would suggest to me (as the units are sealed) that your problems are from having them mounted on the door. They are really meant to be used on frames and this would give you a longer life.

They can be mounted to either horizontally or vertically (slight angles usually work but is not recommended). I think the only rule is that on vertical mounts the word aritech has to be horizontal (it can be upside down)

[Guest cdaly]

IIRC, it's something like a ballbearing sitting on 4 pins, when the ball moves (when hit) it opens the circuit.

Oh, this is interesting. Presumably it must lose contact with 3 of the 4 before it can open circuit. Or is it more like any two of many pins will be shorted when the ball is properly at rest? This would allow multiple orientations to work.

It seems you can get them all to work for a time, then you have problems. That would suggest to me (as the units are sealed) that your problems are from having them mounted on the door. They are really meant to be used on frames and this would give you a longer life.

It's getting to look that way. All of the other sensors are frame mounted and seem happy.

They can be mounted to either horizontally or vertically (slight angles usually work but is not recommended). I think the only rule is that on vertical mounts the word aritech has to be horizontal (it can be upside down)

41499[/snapback]

I'll experiment with orientation on the existing faulty module (dunno if the shop will accept it back a third time..) and then see about moving the sensor.

Great advice, thanks!

[secboy]

I agree with the point about the sensor not being fitted on the door those pins and the ball are often coated in thin gold to improve the contact and are meant to sense vibrations if you mount it on the door it must be like an elephant dropping on it every time the door closes, they are mainly intended to sense the door being kicked in or forced with a crowbar so dont worry about the fitting on the frame if you cant get it sorted then it might be a good idea to try a "viper" sensing is electronic and the unit has its own built in analyser which has many sensitivity settings,they cost about £10-£12 but once set up on the door frame (if poss) should be as good as gold.

In my experiance the pin/ball bearing type are best used on secure room walls/window frames or where the ambient vibrations are low,hope thats been some further help? Paul

[Guest IM_Alarms]

I had this exact problem with a block of flats, all systems having Vipers to the windows. It took ages to find the problem with lots of trial and error, until i discovered that the magnetic contact for the window, was in-line with the miniature relay inside the viper thus gradually magnetising it into staying open or closed. I had to move the magnetic contacts further from the vipers in the end to solve the problem.

I hope this saves you the months worth of visits it cost me, along with the fivers for the congestion charge as it was two roads in the zone!!

[C.S TEK.]

I'm having trouble with a self-installed aritech alarm system where one shock sensor goes bad on a regular basis.

The alarm board is IIRC a CS350 (6 zones, remote keypad), the sensors are aritech reed/shock combo sensors (can't remember the model number).  On one door, the shock sensor module goes bad on a regular basis.  It's on its third sensor at this point and I've had to bypass that one.  It goes like this:

• install new shock sensor, all is fine
  
• after a few months, at setting time, the zone shows open
  
• A thump on the door settles the sensor and the alarm sets
  
• The level of thumping required gets progressively worse
  
• Finally, the sensor won't reset and has to be inhibited
  

Replacing the shock sensor module (into the original body with original reed switch) fixes everything for a time.  If I remove the unit cover and dismount the shock sensor (leaving it connected) and leave it hanging, it resets.  Once I remount it where it should sit (the word 'aritech' on the front should be horizontal according to the manual), it goes open circuit again.

The sensor is mounted on the inner edge of the door with the magnet on the door frame.  The magnet is pretty close to the shock sensor.  The wiring to the sensor is arranged so it does not kink when the door closes / opens.  This sensor is the end of line on this (three wire) zone and has a 1k resistor in the tamper line and a 1k across the sensor contacts.  The wiring is an extension from the original end of line in the room next door (this door was fitted after the alarm wiring was installed).  The door has a weather seal close to the sensor and there appears to be no sign of moisture in the sensor casing.

I've done all of the fitting myself and am happy that it's correctly done.

Is there anything I can do to test the sensor, my wiring, the magnet placement etc.?

I have the manual that came with the alarm board and the bit that details the three-wire tamper circuit setup.

Thanks for any help you might give...

Conor

41482[/snapback]

Why r u using 1k resistors. It should be 4k7 across and 4k7 EOL.

The cs350 did have a dodgy zone, I think it was number five that always caused a problem.

Chris

[Guest cdaly]

Why r u using 1k resistors. It should be 4k7 across and 4k7 EOL.

The cs350 did have a dodgy zone, I think it was number five that always caused  a problem.

Chris

41570[/snapback]

Sorry, my mistake. I'm using the 4k7 resistors that came with the board. I just saw mention of 1k somewhere else on this forum and got distracted... I can't remember if this door was on zone 5. It was originally on a zone that did not allow inhibit so I moved it to zone 1. I think zone 5 is now the entry/exit zone.

I hope this saves you the months worth of visits it cost me

Happily, in my case the alarm's at home so there are no special visits required.

Reading the manuals I see the sensor {a GS611} allows for mounting in all orientations including facing downwards so moving to the frame should be sufficient.

"viper" sensing is electronic

Do these require a separate power supply? I don't think I have any spare cores available on the cabling to this zone.

[Guest cdaly]

Update:

So I moved the sensor off the door and onto the frame. It's facing downwards now and happy on the shock sensor that went bad while on the door. I'll keep an eye on things and see how it goes.

Thanks all for your prompt and helpful advice.

Conor