Hi Guys!
I am a french guy so sorry for my english. I dont know if I need to make a presentation before posting or not!
I found your forum after a long research about my new echomap CHIRP 92SV! I is really helpful for me because I sent email and ask on garmin Marin Facebook some question and they just ask me to call an other service. So they dont know.
I had an elite 7 HDI before with really good down image, better for me than the downvu on my garmin. Fish just pop on the screen easily, now after maybe 20 hours of fishing I never so fish like before. I tried to ask garmin about the dedicated crystal on the down vu or not... no answer yet. But anyway it is not the reason why I am here.
On the sid vu I have a black line on the 800kHz ducer and nothing on the 455kHz. You can see it on my image (sorry it is not a good screenshot but a phone pic).
First pic on 455kHz: almost ok fish on left side, nothing on down, some stuff on 2D. I tried brightness/contrast/TVG setting and mixed them... NO fish on down...
2nd and 3rd pics: first part of the side vu is on 455 and end part is on 800kHZ, You can see that black line on the 800 Khz witch is absent on 455Khz.
I fish only freshwater and max 30 meter. So for me 800kHz is (should be) the best way.
I tried to move the ducer (up down roll on the left on the right)... nothing change but when i roll on one side (maybe i should say "tilt") the black line is stronger on one side and weaker on the other but never disappear.
so if you have any idea i would be very happy to read you!