I have a Lowrance X-75 on the bow of my boat (using the MK Universal Sonar transducer). For some time the display has been erratic... particularly if the voltage is below 12.5 Volts. Dark vertical bars appear, widen and sometimes cover the whole screen. The display also appears to shimmer when this is happening. Today it happened after the batteries were fully charged and the voltmeter display on the unit was showing 13-14 volts and the charger was still connected. It went away after the unit was on a few minutes. I suppose there could be a wiring problem but the voltage would have shown a drop, wouldn't it? The unit came with the boat so it is at least 5yrs old...maybe more. Ready to replace it with and Eagle 480 but don't want to do that if there is nothing wrong with the unit.

