Hi all
has anyone done any exploratory/repair work on these sort of things? You
know the ones, they operate in the 433MHz band I think, and you set some
DIP switches on both bell push and receiver so that the codes match.

I know they are cheap rubbish, and the attrition rate is high; nevertheless I
am thinking of taking a closer look at one that has stopped working. My first
guess was imply that the press switch had failed; but it's a PCB mounted switch
with an ON resistance of 50Ohms, which seems at least hopefull.

There is some failry shonky soldering, some of which I will probably redo. There
is also a little rust on a 3-wire metal cased part with '433.920' marked on it;
a SAW filter I assume? I guess this may have failed, but the LED on the bell push
doesn't go on when you press the switch, and I think this is independant of the
oscillator/transmitter. Oh, and yes I checked the batteries...

As I say, not a big deal, but I'd be interested if anyone knows of any common
failure modes before I get in too deep...

Thanks (and a ding-dong New Year to you all!)
Jon N