Garmin 300c fishfinder will not turn on

The PWR button also adjust the backlight of unit. Press and quickly release to cycle through brightness settings. All else fails call Garmin www.garmin.com/support

My experience as a user is that turbulence around the transducer can cause mine to flash and the depth to remain static.Is your fault affected by speed? Sounds to me that you have a faulty connection causing the transducer to "not register". I'd check connections and also the integrity of the transducer. Hope that helps...
Best of luck

Hello, First check to see if you are getting power to the unit. If you are then remove the battery for 2 mins and then put back in. Try turning it on, if still doesn't power up then will have to be repaired.

Most likely its a feature...does it blink and lose its brain in shallow water (<10ft) with heavy vegetation? If so its likely that the processor is experiencing what software folks refer to as a minor frame overrun... which means it is unable to compute all the math and update the screen before the next wave of data comes in. As a result it loses its brain so to speak - its unable to update the display/data. I called garmin and asked the tech person and that was essentially the answer I got. Gain won't help. Get out of the weeds! Too bad, its a nice color screen with good features... If you can live with this in shallow water its still a pretty good value. Heck if your fishing in shallow water you don't really need a fish finder...

mode then push unit then push reset to factory settings

You might want to post this question in a different section. This is the computer section.

Maximum voltage for that unit is 33V. Test the voltage with a multimeter at the fuse block or as close to the unit as you can. If you are reading less than 33 volts than your voltage input is fine and you need to contact garmin for a repair or replacement if your unit is still under warranty.

Also check your connections at the battery; make sure everything is clean and that you do not have any + and - wires switched.

possibly.most ive owned will flash random numbers when out of the water.the fact its flashing or reading numbers at all,means its working.youll have put it in water to see how accurate,obviously

Hi!
If the unit shuts off on its own, firstly check your power supply. I keep seeing customers running their ssounders from a small, portable battery configuration that doesn't put out the correct voltage...mostly seen with AA size batteries being rated at 1.2 or 1.3 volts (8 batteries times 1.2 volts is only 9.6 volts).
If the power supply is not the issue then I would say the internal power circuit is suspect...this can only be repaired by a competent repair person who knows how and what they are doing. If you open the unit up, you'll not only void the warranty, you run the risk of killing the entire unit from static shock.
Best of luck in your repair!
Mike

I checked the fuse and it looked OK, however working on a hunch I decided to replace the fuse anyway. This immediately addressed the problem and my Fishfinder is now working again.