mtutts Posted March 18, 2009 Posted March 18, 2009 Hi, I have inherited a Scantronic 9448+. Every time there is a power cut, the Bell box on the outside of the house sounds but there is no power to the key pad within the house to turn it off. This is not only annoying for me but for my neighbours too. This happens even when the alarm has not been armed at the time of the powercut so can only assume that the system believes it's been tampered with. Any ideas on why the back up battery isn't feeding power to the key pad, or is it simply the system hasn't been connected up correctly? The key pad works fine when the mains power is connected and I've not had any other issues with the system (other than the volume of the exit tone - talk about drawing attention to yourself everytime you leave the house - not my idea of security!! - i've tried omitting zones - apparently this is supposed to reduce the tone by 30% - nope. Any advice on both points would be great, Thanks.
Guest RJBsec Posted March 18, 2009 Posted March 18, 2009 You need the battery checked , may be dead or maybe battery fuse blown - it won't go away get an engineer in.
Chorlton Posted March 18, 2009 Posted March 18, 2009 just like in cars rechargable batteries don't last for every which is one of the reasons that just like cars intruder alarms should be serviced. how old is the battery and when was the system last serviced? if the answers "don't know" = service required
Fred555 Posted March 19, 2009 Posted March 19, 2009 New battery required - but also check with a multimeter to see if the fuses have gone - you don't need to remove them just look for a volt drop across them - set multimeter to dc volts, touch probe to each end of each fuse holder - voltage readout should be miniscule [if you get more than one volt you have a problem] and you have also just proved that the fuse holder is gripping the fuse tightly enough not to be causing a high resistance fault which will behave like a fuse that blows then un-blows if you see what I mean. Then with multimeter still set to dc volts disconnect at least one wire from the battery and read what voltage the control panel is supplying to the battery - should be at least 13 volts dc but if no voltage or very low voltage and there are no fuses blown the control panel is finished because nobody changed the battery before a battery cell failed (there are 6 cells each making 2 volts wired in series hence 12 volts but if one fails the voltage goes down to 10 volts) and that effectively puts a hefty constant load on the control panel which on the smaller / cheaper ones generally finishes off the rectifier part of the power supply so that is the end of the panel. One other thing to try is to disconnect the Aux 12 volt supply and any speaker supply (one wire off each will do to break the circuit) in case there is a short drawing power then see if you get a reading at the battery leads (again at least one disconnected). The 9448 must not have a battery bigger than 2.1Ah according to the manual check your 9448+ manual and see if it says the same in the specifications page. I downsized the battery in a 9448 I was called to once and all kinds of weird behaviour went away - why? You would have to ask the manufacturer as it makes no sense but it does make a difference in my experience. If you have frequent power cuts in your area the battery life can be shorter than the recommended limit of five years as the type used for alarms generally do not like to frequently cycle (be emptied of power [discharged] and then charged up again). Although there is no good scientific reason for this I find that small batteries in alarm systems generally fail by a cell going short circuit and therefore applying a load which if not spotted blows the control panel but for some reason larger batteries (7.0 Ah and above) seem to fail more benignly by loosing capacity overall but not blowing a cell so instead of supplying enough capacity to keep a system running for a good 12 hours during a power cut it will only supply a couple of hours but the voltage generally still behaves under load as if the battery was fine just the bigger battery is emptying way too quickly for its size. You might find a volume control adjuster (potentiometer) inside the keypad or if it is all in one the main box to turn down the volume it will be marked as volume or something similar - do not turn or adjust anything else or unmarked!
Guest RJBsec Posted March 19, 2009 Posted March 19, 2009 Before you do any of the above, for safety's sake isolate the mains - mains voltage can kill! When you do and the alarm goes off outside you're back to post 2.
Fred555 Posted March 19, 2009 Posted March 19, 2009 Before you do any of the above, for safety's sake isolate the mains - mains voltage can kill!When you do and the alarm goes off outside you're back to post 2. Calm down! Because if you "isolate" (switch off) the mains supply and the battery is almost certainly dead where exactly are you going to get the voltage from to perform the voltage tests on the battery leads? Nor will there be any power for a volt drop test on the fuses - you would have to isolate power for resistance tests but that is to avoid either blowing up the multimeter or getting spurious readings from the multimeter. There is no mains voltage anywhere beyond the mains transformer in any control panel. Just avoid the mains terminal block and the mains input to the transformer and you will be ok. Bear in mind that a telephone line can also deliver quite a jolt. Remember the old trick when using a multimeter - keep one hand in your pocket - it is an excellent bit of safety advice - does anybody out there care to remind everyone the theory behind why this is such a good idea? No cheating by peeking at Google!
djrock Posted March 19, 2009 Posted March 19, 2009 Calm down! Because if you "isolate" (switch off) the mains supply and the battery is almost certainly dead where exactly are you going to get the voltage from to perform the voltage tests on the battery leads? Nor will there be any power for a volt drop test on the fuses - you would have to isolate power for resistance tests but that is to avoid either blowing up the multimeter or getting spurious readings from the multimeter.There is no mains voltage anywhere beyond the mains transformer in any control panel. Just avoid the mains terminal block and the mains input to the transformer and you will be ok. Bear in mind that a telephone line can also deliver quite a jolt. Remember the old trick when using a multimeter - keep one hand in your pocket - it is an excellent bit of safety advice - does anybody out there care to remind everyone the theory behind why this is such a good idea? No cheating by peeking at Google! How do you know that mtutts knows where to avoid touching when the mains is still connected?? RJBsec is thinking of there safety. 240v shock is not very nice! djrock
Chorlton Posted March 19, 2009 Posted March 19, 2009 How do you know that mtutts knows where to avoid touching when the mains is still connected?? RJBsec is thinking of there safety. 240v shock is not very nice!djrock QFA this a public forum and our advice must be to take extreme caution near mains power, period. see here - http://www.thesecurityinstaller.co.uk/Cont...service_pt1.asp and here - http://www.thesecurityinstaller.co.uk/Cont...service_pt2.asp note the warnings in bright red! C.
hpotter Posted March 19, 2009 Posted March 19, 2009 Remember the old trick when using a multimeter - keep one hand in your pocket - it is an excellent bit of safety advice - does anybody out there care to remind everyone the theory behind why this is such a good idea? No cheating by peeking at Google! Its a wall mounted 9448 fred, and we're dealing with general public who may not understand that 50mA @240v will kill as we all do. From a liabilty point of view I agree with djrock. edit, sorry, Chorlton too quick, or me too slow.
lawandorder Posted March 19, 2009 Posted March 19, 2009 Its a wall mounted 9448 fred, and we're dealing with general public who may not understand that 50mA @240v will kill as we all do.From a liabilty point of view I agree with djrock. edit, sorry, Chorlton too quick, or me too slow. I totally agree, an experinced engineer would rarely isolate a mains supply when testing an alarm system but an experinced engineer would know what to avoid. No disrespect intended to the OP but an inexperinced person working on anything that contains mains voltages is at risk, for all we know the system may have been installed by a complete cowboy who has left live wires laying about in the bottom of the panel. If attempting the "one hand in your pocket trick" always use the hand that isn't in your pocket to hold the meter probes, failing to observe this simple yet critical point can lead to unfortunate and painful body piercings with the subsequent inability to father children.
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