On 27/12/14 13:39, David wrote:
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

If it is a fluoro., then yes it has an inverter and a current limiter:
basically whizzes up to about 200v ac, then the tube fires, then the
voltage drops to IIRC about 90v peak.

there shouldn't be much on the HV side..half a ferrite transformer and
some sort of ferrite cored choke/current limiter.

the usual suspects here are switching transistors and electrolytics and
bad joints.

if replacing those doesn't work - chuck it. You can buy a new one fr
less than the cost of fixing the old.:-(





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