Good evening, I've returned from a taxing and frustrating day trying to refresh an old wired alarm system. The panel is an old OptimaXM wired to four PIRs, a door contact and a PA button plus the bellbox. I successfully installed a new Texecom bellbox after (eventually) figuring out the connections. I removed the PA key and looped it out on the panel because the customer no longer wanted it, and swapped out the four PIRs with Texecom compact IRs. Installed a new panel battery. All the wiring was similar to the existing detectors, +/-, N/C, tamper loop. The only odd part about the wiring to the PIRs was each PIR had the same wiring colours, however, at the panel, two of the zones were changed from the expected red/yellow used on the alarm loop to brown/orange. I saw that 8-core wires had been shared on two of the zones but didn't understand why. So clearly there was a joint in the wiring that I wouldn't have a hope of finding. When I came to doing the tests the bell tested out, the strobe tested out, but, the PIRs weren't registering at all. Initially I had them all jumpered for EOL wiring on 1k resistor range and did the same for tamper loops, only because that was the suggested setting for Honeywell as per the instructions and Honeywell took over Optima. Only one PIR was picking up movement and the LED was flicking on and off as it should, the others were just 'dead'. They would not walk test, any of them. I checked for power in each one and it was present. The walk test on this panel is similar to Texecoms it beeps when you trigger the zone and stops beeping when it shuts off. So, I phoned Texecom support and whilst understandably they couldn't help me with the panel they did suggest that because its an 'old' panel it probably isn't designed for EOL wiring so to remove all the jumper links and tried it without. Now three of the PIR zones were just permanently triggering in walk test and I could not get this corrected. I feel sure that the Texecom detectors should work on this panel but for some reason the movement isn't being detected. I had to leave site with the panel in day mode but not usable. Driving home I was racking my brains to think what could be causing this and thought perhaps it could be the change in the wiring in the system. I think I am right in thinking the N/C alarm terminals aren't polarity sensitive? But, I thought I could be inadvertently series wiring three of the detectors if I don't know how the join has been done brown to red or brown to yellow? Is that a possibility? I thought perhaps switching round the red and yellow on the detectors could solve it but I'm not sure. I cant see that its a compatibility issue? I am not clear what to do. I said I would try to find some newer versions of the Optima detectors to change for the Texecom ones, presumably now Honeywell, but, I can't really see how they would be materially different in operation to Texecoms? I think it has to be something to do with the mixing of the two colours in the alarm wiring. What do others think?