I wonder if the solenoid valves are stuck shut or have just been affected by age and failed. If the horns themselves still work I would get some off the shelf solenoids with the right voltage and replace them to get it back up and running at 100%. I guess that's one nice thing about these compared to the DC mechanical sirens we have in the US or the pneumatic sirens in Germany and elsewhere. Solenoid valves can be a lot easier to source and replace compared to motors. 😅
The problem is, where the control is mounted, right at the top of the roof of these old buildings, there is no thermal insulation. It gets very warm up there in summer and very cold in winter. Add to that moisture and dust and the valves stick. This, together with the fact that they are not controlled or moved for a whole year, results in the result that you can hear in the video. But since the Swiss Federal Office for Civil Protection has ordered that this type of siren must be replaced with new Delta sirens by the end of 2024, repairing it is no longer worthwhile.
Man überlege, die Ventile ruhen ein ganzes Jahr lang. Und dann braucht es manchmal mehrer Durchläufe, bis sie wieder einigermassen gängig sind. Leider ist die Zeit gekommen, sich davon zu verabschieden. Die Sirenenwelt wird nicht mehr die gleiche sein ohne die KTG!!
