My garage alarm siren was sounding a bit quiet and the tone was weird, like mixed with another tone.
Powered up it draws about 14V 300mA with a spike to ~1A briefly during the low pitch yelp, seems normal.
Teardown reveals only two electrolytic capacitors inside, so I replaced them. 100uF 25V for the warble ramp, and 47uF 16V for decoupling.
The old ones tested OK sort of? - 100uF reads 68uF (-32%) ESR 0.80Ω, and 47uF reads 41uF ESR 0.87Ω as well so it was a bit confusing if the caps were to blame.
The tone caps are green film caps I left alone. Newer...
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