Normally these are little blocks that are unserviceable. In answer to your
question yes they use the same tubes as are used on the mains, but instead
of the starter, choke and capacitor used in the mains version to heat the
heaters, and give a higher voltage to strike the tube, the job is done by an
electronic circuit. There seem to be two types, Cheap cold cathode ones and
ones that emulate the heater use.
If the circuit is duff, the cahances are its pretty terminal as mostly its
the inductor that dies, usually gets damp in it and pops its clogs taking
the semiconductor with it. I'm sure new units are available from source on
the web.
If you have checked the tube of course. Normally they are the same fittings
as ordinary ones so find one and test it.
Personally, I often found them annoying in motor caravans with their
radio interference issues and ability to self destruct.
Brian

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From the Sofa of Brian Gaff Reply address is active
"David" wrote in message
...
I am trying to fault find a fluorescent light on the 12V circuit in our
motor home.

Opinion seems mixed, but there are several postings which claim that these
are actually 240v AC lights with a built in inverter so that they can run
off 12V.

There is certainly a lot of circuitry inside.

Firstly, do camper/caravan/boat 12V fluorescents usually run at 240V with
a built in inverter (or sometimes)?

Secondly if so is there usually clear marking of the 12V and 240V parts?

I don't particularly want to probe a 240V AC circuit with the 50V DC part
of my little multi-meter.

Cheers

Dave R

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Windows 8.1 on PCSpecialist box