Why would they have to be unpolarised? Just 2 paralleled together to get
the required capacitance. Any polarising mark on the SM carrier strip
perhaps


I don't think that they *do* have to be un-polarised, as such, given the
ones that Phil has found. I think it's just because they *are*, if you see
what I mean. To be honest, I never knew that you could get multilayer
ceramics in such high values. Presumably, they don't go up as high as 47 uF
which the designer felt he needed, so he just put 2 x 22 uF in parallel
instead. As I said, the circuit is absolutely un-critical in that it only
needs to produce a small amount of DC from the incoming mains to power the
LED in the opto that produces the muting signal. Because of time constraints
with ordering-in those ceramics, I think I'm just going to go with a pair of
small tants, fitted to observe their polarity.

Arfa