GrahamB

Great info, cheers.

Yeah, I did Comp. Sci. as my main degree and usually transmit/receive get flipped (as in RS232). Each field has its way of doing things I suppose. Yeah, the voltage seemed incredibly low when I finally stuck the meter on it. The battery looks physically tip top though. Will look into checking the battery charge circuit. If you have tips on this, I'd by interested to hear them for sure. Best, G.

The battery being the issue seems unlikely to me. If it were the case, why did the alarm function fine when I replaced only the keypad? The old battery was capable of sounding the internal alarm, registering trips on all the sensors during a walk test, and triggering the bell box on alarm activation. Just because you haven't seen it, doesn't mean it doesn't happen. Had I replaced only the battery, I wouldn't have fixed the fault, clearly. "You said "My control unit and battery seemed perfectly fine" but someone queries the battery and you check again?" Usually I don't reply to these sorts of remarks - there have been a fair few in this thread - but on this one occasion, I'd ask you to question the purpose of this statement you've made here. What do you hope to achieve by it? You don't have to reply to me, just ask yourself. The battery seemed perfectly fine, as the alarm worked perfectly fine. However James Wilson made a useful comment about testing, which is great - that's the purpose of these forums after all, right? Are you here to learn and help others? That's why I'm here. I hadn't touched the programming of the alarm at all when the back door sensor switched modes, so there's no chance of "accidentally" here. The control panel is the original one. I only programmed it, to fix it. You believe what you want though, it's a free country. "For few quid more you could have bought the panel which comes with a keypad, that may have been sensible depending on age and if you suspect damage." Obviously fairly useless info for me at this point, although useful for any DIYer swinging by. I suspect anyone carrying out this sort of fix is going to research prices and value for money. As it happens, your suggestion is precisely what I did in the first instance and the new control panel is now in the loft for spares in the future. "Car battery testers can damage alarm batteries, depends on the type." Thanks. A useful piece of info and appreciated. They do come occasionally here if you're not put off by the tone of many of the posts. I'll be sure to do my research before making a purchase. "No point stuffing a new battery in if the charging circuit is blown, you'll just kill another one..." Yeah, I did the other tests in the manual and the alarm is working just fine. But thanks for your concern. G.

Good point. Putting a voltmeter on the battery this morning after a night's charging shows it far below proper value (5v vs 12v). New one on order. I'm also now looking for a battery tester which can perform a load test rather than just a voltage test. I'd guess a car battery tester (12v + lead/acid type) would work for this task, do you agree? I think it would be useful for the car and motorbike anyway. I only replace my car battery once it starts to sound feeble when starting (which is probably once every dozen years), however I'm now wondering what a test would show re battery health. Thanks for the prod.

Just replying back here in case any other DIYers swing by and have the same issue. I suspected my keypad PCB was at fault given there was power (backlight was on) but otherwise no sign of life. So I got a replacement - ~£40 or so (more than I reckon it should cost given what it is, but I suppose volumes are probably low). The installation manual for the 8,/R8/Compact is easily locatable on the internet with a bit of searching. My control unit and battery seemed perfectly fine after the power cuts. Fuse was unblown. Attaching the new keypad was trivial, with one slight caveat - the transmit and receive lines aren't wired crossover between the keypad and control unit (i.e. T->R, R->T) as would be the case with a typical serial digital coms line (like RS232 for instance). So make sure to wire T->T and R->R. Everything's clearly marked on the control panel PCB (and in the manual). Another oddity - my zone 2 circuit (garage access door and downstairs bathroom door) were wired as either "Inhibited Entry" or "Guard" (based on how they used to work) but after reconnecting the keypad, I noticed they were tripping even when the alarm was unset. Thought this behaviour was consistent with a "Fire" alarm mode. When I went to re-program that mode it did indeed show as Fire. So it looks like some bits got flipped in the non-volatile memory when the power was interrupted (likely a surge in the control panel PCB?). Programming is pretty trivial though - all in the manual and very easy to comprehend. Walk test showed all sensors working (although I have 2 zones that each have 2 sensors - rather than one sensor per zone - which was news to me). Happy days.

Getting someone else to do it is always easier and less time consuming. Some people don't like to be dependent on others, although it's not always possible. I do my own electrics in the house, plumbing, building work and car maintenance. Pretty much the only thing I don't do is gas work. I don't grow my own food either, although I could probably turn my hand to it in a bind. I recognise that electronics systems are non trivial and the alarm system may pose a significant, perhaps insurmountable, challenge.

Do you have any links to documentation for this make / model? Such as a downloadable service manual. I'm reasonably technically minded.

So you reckon I should pay someone to sort it out?

Hello, We've recently suffered a couple of power cuts and after a length period of beeping from the control panel after each outage, our keypad is now inoperable. The back light is still on, but pressing the keys appears to do nothing (produces no audible or visible change). I've taken the front cover off the keypad and expected some sort of anti-tamper alarm to start sounding, but nothing. No visible signs of damage to the circuit board. Control panel light is still on. Any ideas what may have gone wrong? The system is at least 8 years old I think. Was there when we moved in. Many thanks for your help, Graham,