Cambridge L-Nav problem -- runaway vario

At 17:02 07 July 2014, jherzog wrote:

I have a nagging, recurring problem with my trusty L-Nav. Occasionally
when I power the unit on, the lift tone sounds constantly, and the vari
display is pegged at maximum lift (10 kts). It's clear that the proble
is with the L-Nav, and not the electric vario display, as the ton
continues to sound once the electric vario display is unplugged, and th
problem continues once the vario is plugged back in.

Cycling power once or twice will sometimes, but not always, make th
problem go away -- until the next time. Last Friday, the proble
persisted for two hours, finally disappearing as mysteriously as i
came. Once the L-Nav powers on correctly, it has always staye
operational for my entire flight.

Has anyone else experienced this, and found a solution?

Thanks,



I have exactly the same problem with my L Nav but over the season have
concluded that the problem is more likely to occur if there has been
dampness in the trailer. Over last winter it stopped when I put a
dehumidifier in the trailer. Over this summer it only happens after a few
wet days. but thats in UK type weather conditions. The summer has been
fairly dry by our standards and as you say cycling the power usually makes
it work fine.


Mike