Alarm sounds when mains switched off.

[bri160356]

My son has recently moved house and the property is protected by an ‘SL Compact’ burglar alarm system. I’m not sure how old it is but it appears to function properly when the alarm exit code is set, and it de-arms itself normally when the entry code is keyed in.

However, when the mains supply to the alarm is switched off the alarm panel itself goes completely dead,…no led’s lit and no sound from the panel whatsoever;...unfortunately the bell-box/sounder immediately activates at full volume.

The only way to stop the bell-box/sounder is to restore the mains power and key-in the 4-digit code.

Very inconvenient because he needs some electrical work in other parts of the house but as soon as the mains power is switched off the bleedin’ alarm goes off!...neighbours not pleased!

Am I right in thinking that the alarm panel should have a back-up battery to prevent this happening?...is the battery knackered?...or is something else amiss?

All advice gratefully received.

 

[Nerdish Nerd]

Battery inside the panel is dead, and the bell box is ringing because there is no power going to it when power to the panel is lost. Basically replace the battery inside the panel because it's dead.

 

[bri160356]

Battery inside the panel is dead, and the bell box is ringing because there is no power going to it when power to the panel is lost. Basically replace the battery inside the panel because it's dead.

Thanks for the reply my friend;...do you reckon this one would be suitable?

https://www.amazon.co.uk/Yuasa-NP2-...4116400&sr=1-2&keywords=burglar+alarm+battery

 

[Nerdish Nerd]

How big is the panel? If I'm thinking right it's an Accenta/Optima compact rebrand. Pictures maybe? If it is, that's the biggest size you can fit in it I believe. Kinetic Security sell 2.1 amphour batteries and they seem to work nice, I have one in a Scantronic 9448. They are also sold at around half the price.

 

[sparkymarka]

I would check the battery output first ( multimeter set on d.c around 13.8v ) as the resistor for the battery charging circuit are prone to burning out when not serviced on a regular basis..

 

[bri160356]

How big is the panel? If I'm thinking right it's an Accenta/Optima compact rebrand. Pictures maybe? If it is, that's the biggest size you can fit in it I believe. Kinetic Security sell 2.1 amphour batteries and they seem to work nice, I have one in a Scantronic 9448. They are also sold at around half the price.

Sorry my reply took a while;..I had to get my son to email me a pic of the alarm panel,…he doesn’t live close to me.

https://s26.postimg.org/duam592i1/SL_Compact.jpg

 

[Nerdish Nerd]

That is what I was thinking of all right, but if I remember correctly those models older Optima/SL Compact panels had charging resistor issues (A hobbyist friend of mine had one in their garage. Resistor blew out and panel caught fire. Freak case, by the way) so as Sparky said, check the charging resistor voltage before buying a battery. It may also be useful to check the battery fuse to see if it is making continuity and hasn't burned out due to the battery being old or some other means, because that could also be a reason why there's no standby power going from the battery and to the panel. From what it looks like to me is that the battery is probably quite old and is no-longer holding a charge.

 

[bri160356]

OP here,…many thanks for the helpful replies guys,…all advice taken onboard.

I’ll check out the charging circuitry/battery and see how it goes. Hopefully it’s just the battery!

I’ll update with the outcome.

 

[bri160356]

Update from OP;

I’ve removed the front panel and ascertained that the 12v 2.3Ahr battery was last changed in Aug. 2013.

The charging circuitry is fine,….measured charging voltage of 13.8v when the battery is still connected. Removing the battery conx. the battery voltage immediately drops to 5v so the battery is obviously u/s.

However, on a more ominous note, after removing the front panel, the ‘alarm’ within the panel sounded momentarily then stopped;…the key-pad has lost its power and luminosity and none of the keys are operational.

The alarm panel led’s are working i.e. the power led and the ‘zone’ leds but the alarm itself isn’t working because the key-pad is inoperable.

Any thoughts please guys?...I’m thinking dry-joint or bad connection, somewhere on the main-board, that pinged off when I removed the front cover.

All advice gratefully received.

 

[sparkymarka]

Can you check the large resistor under the keypad on the main pcb does it look burnt ? What is coming out of the battery leads ( dc) with the battery disconnected ? The keypad will seem dead until the cover is back on and reset pressed

 

[bri160356]

Can you check the large resistor under the keypad on the main pcb does it look burnt ? What is coming out of the battery leads ( dc) with the battery disconnected ? The keypad will seem dead until the cover is back on and reset pressed

The alarm panel was working perfectly (apart from the knackered battery of course) until I removed the front cover so a burned resistor seems unlikely,... but I’ll check.

The charging circuitry seems fine ,…it delivers 13.8v but I didn’t meter any current flow tbh.

Once reassembled and the mains was restored I tried the re-set button and every other button for that matter.

Is there a procedure to ‘resurrect’ the panel if the front cover is removed?...there is no back-lighting to the key-pad and the ‘internal sounder’ doesn’t ‘blip’ when the keys are pressed, as it did previously.

I have no instructions/manual whatsoever.

One question: when the mains power and battery is removed how long is the outside ‘bell box/sounder’ likely to last?....is it hours?...or is it days?

if I need to swop the panel I’d rather do it as quick as I can without resorting to getting a ladder up to the bell-box;…I’m not good on ladders these days!

 

[Nerdish Nerd]

The usual procedure for resetting one of those panels is to enter in the code and press the reset button and it should go back into day mode. If there's an issue with either the lid tamper, bell tamper, global tamper as far as I can remember the keypad will lock out and you'll have to rectify the issue before you can press the reset button again.
What I think has happened is that you've surged the 12 volt fuse and that's why you're not getting any backlight or blips when keys are being pressed down. Now It's been some time since I myself have had an ADE product but I've had an issue similar to this and I had to replace the 12 volt fuse to put everything back to normal. It it will be a good idea to check all the other fuses on the logic board for good measure and see if they are making continuity.

Bells will ring when power is cut off to them for a range of minutes to hours depending on how good condition the battery is in and how many amphours the battery inside them is. If it's an old external bell, but it was high end, you'd still be able to trust it's working... just about in my experience. If the battery and components were exposed to the elements without an internal cover over them (I'm looking at the ADE Sonade and those big Type S and C bell boxes) It may work, but then again it probably won't. If it does, you'd be hearing it try to sound and fail halfway though. For the record, this paragraph is in my experience and also from looking at videos of the bell boxes that I listed above.

 

[bri160356]

Many thanks for the replies;…I’ve got a new battery being delivered today so I’ll fit it and see how it goes from there. I’ll check all the fuses but I’m not holding out much hope for the panel itself tbh.

Probably be Wednesday before I can get back to the job;…I’ll update with the results, for anyone still remotely interested.