A common failure for the E80 and E120's is the backlight. either the light itself or the backlight power supply.. The power supply is most common.
Obviously you probably tried switching it back to Day mode, and turning up the brightness, so if both are set correctly and it's still dim, my first suspect would be the backlight power supply. Unfortunately, there isn't much you can do about it. You "might" be able to find a used but working power supply board on Ebay or something and replace it yourself. But last I heard Raymarine
no longer has the parts
so they can't repair.
On our boat
, I have two E80's, 12 years old, and the backlight does crazy stuff anytime it's not in Day mode AND also full brightness. As soon as I dim it or switch to night mode it periodically goes bright, off, then back on. This is the backlight power supply failing and restarting. It acts *better* (but not perfect) when the battery
voltage is high, so I inserted a voltage regulator
to power the electronics
and set the voltage output to a constant 13.1V. It helps but the problem still happens.
If voltage is good, and you aren't willing to tear it apart and try to repair yourself, there's not much you can do but replace it with a working used unit, or a newer one along with a SeaTalkNG to SeaTalk1 converter to maintain connections to your existing instruments. If your radar
is Digital (connected by an ethernet connector, not an old round connector with lots of pins) then you can keep using your Radar
with even the newest Raymarine MFDs.