Furuno Problem

[jlogger]

Furuno Problem

I have been having an intermittent problem with my Furuno 620. Sometimes the depth displayed is incorrect according to the number displayed but the bottom is correctly represented by the screen. The deeper I go the more the difference is. I had the problem at the end of last year, but at the beginning of this season it was OK. Now it is incorrect again. My question is, transducer or head end problem or maybe some sort of ground issue? There is another transducer near the one for the Furuno but even with that unit disconnected I still see the problem. My thought is that if one or the other depth is correct, then the transducer is OK. I don't know enough about how the transducer interfaces with the head end to be certain though. I attached a photo that shows 79 fow on the bottom display but 108 fow on the numerical display. In 20 fow the numbers would be more like 14 fow and 18 fow respectively. Thanks.

[Sk8man]

Does the unit allow you to reset it back to the factory default settings? Ifso that is where I would start.

[jlogger]

Good point, I would bet that it does. Not sure why or how settings would change though, but that might at least offer some hints as to what is happening if anything changes after that.

[UNREEL]

I assume it's dual frequency. 50 & 200 ? Does it happen with both in dual mode?  Also is the difference there in manual and auto depth mode

[jlogger]

I believe the problem was there in 50 and 200 but i did not check dual mode. I always run it in manual so i don't know about auto depth.

[J.D.]

I also have been running the 620 for the last 7 years using an Airmar P66 transducer.. I notice on your screen shot you are using the 50 khz. wide beam alone. I'm willing to bet the transducer is pinging the depth along the long angle of the beam, IE: the hypotenuse  of the triangle, not straight down to the bottom. The deeper you go, the farther off the reading will be.

I always run in dual frequency, wide beam to scan for fish, narrow angle to mark bottom accurately.

Furuno  has a setting that allows you to add or subtract gain from each cone angle. Try backing off the gain a few clicks in the wide beam, or add a few clicks on the narrow beam. Also, check the transducer mounting and adjustment angle, sometimes the screws holding the transducer to the bracket get a bit loose and the transducer moves around under wave action.  Hope this helps.

Jim S.

[jlogger]

19 hours ago, J.D. said:

I also have been running the 620 for the last 7 years using an Airmar P66 transducer.. I notice on your screen shot you are using the 50 khz. wide beam alone. I'm willing to bet the transducer is pinging the depth along the long angle of the beam, IE: the hypotenuse  of the triangle, not straight down to the bottom. The deeper you go, the farther off the reading will be.

I always run in dual frequency, wide beam to scan for fish, narrow angle to mark bottom accurately.

Furuno  has a setting that allows you to add or subtract gain from each cone angle. Try backing off the gain a few clicks in the wide beam, or add a few clicks on the narrow beam. Also, check the transducer mounting and adjustment angle, sometimes the screws holding the transducer to the bracket get a bit loose and the transducer moves around under wave action.  Hope this helps.

Jim S.

That makes some sense. So the signal that marks the bottom on the screen and the signal that gives me the numerical depth are separate then? I'm just trying to understand a little more about how the transducer works.

[J.D.]

It could be.... Once you're on the water, press the "auto" knob, and change to "fishing" mode. Set the transducer to high frequency only and see it the bottom depth on the chart matches the readout number. If it does, try the same thing with the low frequency only. If the readout number is larger than the actual bottom reading, it's reading the cone angle and not the bottom.  Switch to duel frequency, and you should have matching numbers. I've never run the low freq. by itself, always in duel mode. 

 

Remember:  transducer shows the distance between the transducer and the fish - not how deep the fish is from the surface.  I use the narrow, high freq. for fish depth, the wide angle low freq,. lets me know if bait and fish are in the general area. 

[jlogger]

Well problem found. I took my deck brush to the transducer, cleaned it down a little and made sure it was all the way down in its normal position. Problem immediately stopped and everything worked great all day. It's always the simplest thing. Thanks to all. 

[UNREEL]

 That was easy!  Thanks for starting this thread. I used JD's advice and tweaked my gain settings on my FCV-627. Backed off the 50 and upped the 200. In the dual mode I usually ran my gain in off position and adjusted for best picture. Now I keep it in fishing mode and seem to get a better screen.

[J.D.]

Unreel, Once I get setup out there, I slowly increase the gain until  dots appear on the screen, then back off just a bit. I can see my Blacks stacker releases on the cable down 80ft..  If there is a good thermocline, you'll be able to see that too.

[hawkeye625]

Anyone have a solution to getting a Lot of clutter when trolling into waves? 50 Hz setting. I have to turn gain way down just to view the bottom when waves get 2 to 3 ft.

Sent from my SM-G930V using Lake Ontario United mobile app

[Sk8man]

Might want to check the positioning of your transducer on the transom if that type.