Furuno 620 tuning

[hawkeye625]

So I put a furuno 620 in my boat 2 years ago with the airmar ducer.  It seems to mark bait and fish o.k. but I almost never mark deep fish say over 100ft and the fish I mark say under 80 ft show up more like a blob than a clean hook (looks digitized if that makes sense).  I've seen some screen shots on here from other brands and they look pretty clean compared to my unit. 

 

Just wondered if it was my unit, ducer placement, or an adjustment I'm missing.  I play with the gain alot and just cant seem to clean it up.  The manual leaves a little to be desired and wondered if anyone has some tips that might help.  A unit with this price tag should have a better picture IMO.  Almost has to be a setting I'm missing.  My old Lowrance 520 had a much cleaner picture even out of adjustment.

 

I do mark riggers and even cheaters so I know the unit is working, it's just fuzzy.

 

 

 

Thanks,

Jeff

 

 

[J.D.]

Jeff, I've run the 620 for 4 seasons now and don't have the issues you describe. Here's a few things you can check:

 

Pressing the gain knob, gives 3 choices, fishing, cruising, and off.  The auto gain must be "off" for any of your manual changes to take effect.  You can offset the gain for each frequency. I boost the gain  on the 50 kz low frequency side, almost to the point of having a cluttered screen, and keep the high frequency side at "0".

 

Check the interference settings. Turn it off and see if you have any electrical interference on the screen... use the minimum supression needed to keep the screen clean.  Same thing with low level noise and weak echo settings.... turn off as much of the auto filtering crap as you can to get a true picture...... dump the fish ID icon setting too.

 

Remember, you are looking at a 3D world on a 2D screen.... what you see on the screen depends on how a fish swims through the cone angle. Very seldom do I see that perfect "arch" of a fish ... more often it's a blob, line, or streak on the screen.

 

Check out this link for more help.

 

http://www.thehulltruth.com/marine-electronics-forum/196651-i-need-help-operating-my-furuno-fcv-620-using-sonar-general.html

[hawkeye625]

J.D. I'm getting pretty much the same as the video from the hull truth link.  Set mine up the same as you are doing with the gain in the auto off mode.  Once in a while I'll let it run in fishing mode and it seems to do ok, but usually like to tweek the gain in manual mode.  Also have all the other gizmos turned off.

 

From the sounds of things mine is working fine, just thought the picture should be a little more crisp.  As long as its marking fish I'm happy.  I'll try playing with the interference settings as soon as weather allows.

 

As far as the deep fish, maybe I need to zoom in a little more or something.  I'll see clutter down deep but rarely see the fish archs or marks I would think are fish.  I will get streakers shooting up from the depths, but never really mark them before they start climbing. 

 

Thanks for your help.

 

Jeff

[J.D.]

Jeff, Good point on the zoom range... I forgot to mention that I have my marker zoom range set to read a 60ft. section of water, and key in on the thermocline area. For example, fishing in 200fow, 52 degrees  80 down, will zoom to 50 to 110 range on one side of the split screen, with full depth on the other side.

Edited February 11, 2014 by J.D.

[hawkeye625]

Thanks JD.  That's what I was looking for.  I'll have to play with the zoom feature a little more.  Seems like the best way to learn features of a unit is to take them one at a time.  I ran for the 1st week on the cruise feature, couldn't figure why we didn't mark any fish....then I ran for a while on fishing trying to figure out why I couldn't adjust the gain...finally got a little wiser and took the manual on the boat...but it's hard to read and try to fish at the same time. 

 

Limited time on the water doesn't help either.