[TG11] DragonFly 4S Will Not Power Up

[Tom - Raymarine - Moderator]

Hello Tom,

The power supply is the bottom two pins in the connector, when plugged into the back of the display; on the green connector of the Dragonfly 4's power cable, this is the two pins between the two close-together keyways, furthest from the third, isolated keyway. Looking at the cable connector with the single keyway at the top and the two close-together at the bottom, positive is the left-hand.

If you're getting 0V there, the problem is probably the inline filter on the power cable. If this has failed, the likely cause is high battery charging voltage. The charging output on many outboards is not as well-regulated as we would like and can have peaks as high as 100V. These won't show up on a multimeter (the sampling rate is far too low, and will only show an average voltage), but an outboard mechanic's DVA meter should show the true peak voltage.
If the inline filter is getting high peaks in the charging voltage then it will last for a time and then eventually fail, leading to 0V reaching the display. In this case, it's a good idea to have the charging checked before fitting a new transducer/power cable in order to prevent further failure. As I say, a multimeter is not a useful check, it will not show the peak voltage.

Regards,
Tom