Scantronic 9930 PIR tamper

[james.wilson]

Disconnect the circuit at the panel and meter the tamper pair on the sensor. The tamper switch is the red dot. 

Then short the cables at the pir and measure the resistance at the panel

[Gadget34]

Is this a resistance measurement at the sensor and the same at the panel using a multimeter? 

When you say tamper pair there is only two wires apart from power. Do you mean these?
 

And by short I assume you mean connecting the blue and yellow wire together at the sensor?

 

Is there any expected readings or should I compare to a sensor that doesn’t cause tamper alarms?

 

Thanks

[james.wilson]

Put your meter on 200 ohms. 

Yes short the blue and yellow to check the cable but I'd expect a connection or the tamper switch the reading should be steady and not fluctuate

[Gadget34]

So the first test

 

1) Disconnect the circuit at the panel and meter the tamper pair on the sensor.

I don’t fully understand what to disconnect and which wires to test for this one?

2) Then short the cables at the pir and measure the resistance at the panel. 

So connect the yellow and blue together at the pir and monitor the blue and yellow at the panel whilst disconnected on the meter to check the cable is ok?

 

[sixwheeledbeast]

1) Tamper terminals on PIR will be marked meter them and simulate closing the lid.

 

2) yep.

 

All values should be monitored for a little while and be steady, although no guarantees on finding a very intermittent cable fault, chances point more towards the PIR but need to test these things.

[Gadget34]

Ok I have done a couple of tests.

 

1) I put the meter across the bottom two pins in the sensor which I believe are the tamper ones. With the lid off I didn’t get a reading (no circuit) once I pushed the button it read 0 on the resistance 200k setting.

 

2) I shorted the cable at the pir and tested this at the control box and got a resistance reading of 0. When disconnected I didn’t get a circuit.

 

3) I took a reading of the cable disconnected at the panel with the pir sensor fully connected. This was 02.2 on the meter. With the lid off the sensor I didn’t get a reading.

 

I assume this means it could be the pir? Unless it is one of the resisters within the pir?

 

The PIR model is intellisense IS-215T. Is there a recommended replacement to work with the current wiring (4 wires with the resistor) which I believe is called EOL?

 

 

[al-yeti]

1 hour ago, Gadget34 said:

Ok I have done a couple of tests.

 

1) I put the meter across the bottom two pins in the sensor which I believe are the tamper ones. With the lid off I didn’t get a reading (no circuit) once I pushed the button it read 0 on the resistance 200k setting.

 

2) I shorted the cable at the pir and tested this at the control box and got a resistance reading of 0. When disconnected I didn’t get a circuit.

 

3) I took a reading of the cable disconnected at the panel with the pir sensor fully connected. This was 02.2 on the meter. With the lid off the sensor I didn’t get a reading.

 

I assume this means it could be the pir? Unless it is one of the resisters within the pir?

 

The PIR model is intellisense IS-215T. Is there a recommended replacement to work with the current wiring (4 wires with the resistor) which I believe is called EOL?

 

 

2.2 what? Did you change the range when you read that or left it on the 200ohm range 

 

If you get good reading on the cable , and not correct reading from panel and fault is intermittent?

 

Maybe you didn't put cables back properly , I doubt the resistors can go faulty 

[james.wilson]

You want to be on 200 ohms not 200k for the short tests

[Gadget34]

All tests were done on 200k. I can’t see the cable being at fault though as I could see the resistance change depending on the state of the pir. Lid off there wasn’t a circuit and then lid on it read 02.2. I believe the resistance would then increase further if someone activated the pir motion.  
i read this elsewhere which I believe is what I am seeing as I also measured the resistance and the pir alarm wires and these are 0.46 ish which fits with the below?

 

As an example if a 4.7k resistor is used for the alarm contact and a 2.2k resistor is used for the tamper/EOL,

In the 'active' condition the panel would see 4.7 plus 2.2 equals roughly 7k ohms.

In the 'settled' condition the panel would just see the 2.2 or EOL.

In the 'tamper' condition the panel would see zilch IE cut cable-open circuit or direct short tamper as well.

 

What I don’t know is what reading would be at the panel when the pir is in the fault state I.e causing a tamper alarm on motion with the alarm unset.

 

any recommendations for a compatible pir?

[james.wilson]

agreed but 2000 ohms is a lot. I would expect it to be the pir but if you test the tamper switch at 200 ohms this will confirm, testing set on 200k wont show a high reading. It should be very close to 0.3 ohms (not 0.3 K Ohms) plus whatever size the built in series resistor ir (not the ones in the terminals) you could try adding something to the red dot to adjust the close point if the case is slightly twisted