JimD

I can't see your video (it's marked 'private') but I also inherited a ADE Optima Compact with the house I bought and I've changed the battery several times without using anything but the user code (at least the code I was given by the previous occupant to set and unset the alarm, which I assume is the 'user code'). Disclaimer - I'm not a professional alarm person. All I did was take the cover off (the alarm sounds immediately because of the tamper switch - but you can silence it with the user code), disconnect the old battery and connect the new battery. Then replace the cover and press the 'Reset' button to get rid of the Tamper indication. Mine worked normally after doing that.

I just disconnected the 12v wires in the box and all was fine when I reconnected them after fitting the new PIRs so I was worrying about nowt really. Just the new one to fit in the garage left to do, and that's for another day - I'm confident I can handle it now though. Thanks to everyone who replied to my questions - I appreciate the help I've had from this community. (Edited to add pics)

That's an option - is the inevitable 'noisy' reconnection likely to make the PIRs misbehave at all? The instructions for the new ones mention some sort of 'self test' on first power up.

So the PIRs arrived yesterday, and I'm looking to fit them today. Is there a simple way to deactivate the 12v supply to the PIRs on this panel (e.g. remove one of the fuses)? I don't want to power the whole panel down as the external siren will go off if I do (don't ask how I know). The only manual I can find is slightly different to the model I have (it's for a unit with 8 zones and mine is 6 zones) and doesn't really help me with that. I suppose I could just remove the most likely looking fuse and stick my meter on the 13v output, but that risk a lot of noise happening.

That's good to know swb. Thanks. I've verified that the fault indications are gone with the links in the box removed and the PIR contacts shorted together, so all good there. I also found the red & black cores of the garage cable (with great difficulty though - I'm afraid it's a rats nest behind the circuit board) so I've pushed the button on ordering 3 of those PIRs. I may be back to this thread once the gear arrives. ?

Thanks James. I've separated out all the wires on the switch now so I'll use the red & black for supply and the blue & yellow for the contact on the new PIR. As long as I use the same cores at each end for the same purpose it should work (just I won't have a tamper circuit, but I can live with that).

Thanks swb, I'll check that. Should I be concerned about the level of the DC supply (13.6v measured at the PIR terminals)? It seems a bit high since the PIR is rated at 12v. My meter isn't calibrated of course, but I'd be surprised if it was that far out.

Correction to what I said above - the garage contact has a 4 core cable, not six. Since the tamper circuit isn't used it should work OK though? I have no idea why the red and blue wires are cross-connected like that - I would have expected the yellow & blue to be connected directly to the reed switch and the red & black not used.

Thanks for the replies. I've attached a pic inside the alarm box for info. @sixwheeledbeast Thanks for the advice on the PIRs - given the state and age of the system I don't want to spend a fortune (although I will look at the prices for the PIRs you mention) so hopefully the cheap ones will do the job at least as well as the old ones. There are still 2 old PIRs working OK in other rooms, so hopefully they'll continue. I think the panel is fine - when I removed the garage door contact I went in and linked out both Zone 6 (the garage door) and the 2 faulty zones and the fault indications have gone away (they're all NC contacts). Today I'm going to short out the wires at the PIRs to verify the wiring is OK. The garage door sensor wire is 6 core, including red and black, but there's no DC voltage between any of the wires, so presumably it isn't connected in the box (I'm hoping they ends aren't cut off and inaccessible!). The tamper circuit is not active - it was just left linked out, presumably at installation. That darkening is just on the photo - must have been the lighting - and I can't feel any excessive heat on the panel. I replaced the screws when the pillars broke off and the cover wouldn't stay on. @PeterJames - I've replaced the battery 2 or 3 times since I've been in here. The current one still seems fine as it kept the alarm powered for about 6 hours when we were getting a new consumer unit fitted last year. I'm going to check out the wiring, but the sensor LEDs don't behave normally (sometimes staying on long after any movement has stopped) so regardless of any wiring problems I'm pretty sure they're faulty.

HI all, my first post here so please be gentle with me. So that you can pitch any advice at the right level, I'm a retired electrical engineer. I have an old alarm that we inherited when we moved into this house 20 years ago - the box is marked ADE OPTIMA COMPACT - see attached pics (I've managed to find instruction and installer manuals for it online). Quite a while ago a couple of the PIR sensors started going off for no apparent reason so for years I've just been omitting the zones when I set it, but I've finally decided to try replacing them. Started by googling to see if I could find something that looked like the ones I have, but they seem a little tricky to find (see attached pics of the old ones). The voltage supply to the PIR is 13.5V or so, which I'm assuming is approx 12V, which most of the available PIRs seem to be rated at. I'm really looking for guidance as to what PIRs would work with this system. So far I've found these, which look as if they might be OK, but technical info is very sketchy. - https://www.shg-uk.co.uk/Pyronix--PIR-DUALTECH-15m-FPKX15ED?PPCT=1663776703&gclid=CjwKCAiA9NGfBhBvEiwAq5vSy8eVwt9-sZeluJ9W2qdE6WgxESZz5G8u9W9-Jr2tQlXxuF7x4hIouBoC-awQAvD_BwE I'd also like to install one of these in the garage to replace the old reed switch on the door (I've just had a new door fitted, forcing me to get round to this job). The only drawback might be getting the 12v into there as currently the appropriate cores of the alarm cable going in there don't seem to be connected in the alarm box. Thanks in advance for any help.