So I installed a 998 unit on my boat a few weeks back, and have been trying to get it all tweaked correctly. The install wasn't too terrible all things considered, but I am having trouble with one thing.

My right side imaging is always darker than my left side imaging, by a significant amount. In order to get a good read on the right side, I have to turn sensitivity up and contrast down so much the left side is completely whited out. Below is an example - note the big ball of shad by crosshairs is directly under my boat. On the left side, it is all white (return) while on the right you can barely even see the baitfish ball. This is a flat bottom.





So here I went by this structure in both directions, you can see both times the right side signal is extremely low compared to left side.





This isn't even close to the worst it gets because this is a very hard bottom. On soft bottom the right side is black while the left is full white (I forgot to take a snapshot on a soft bottom). It makes it pretty much impossible to tune in and actually see fish.

On to pics of transom: first pics from the side.





This is on a Glastron I/O, so I had to get the transducer down below the bottom of the lower unit mount. It is somewhat close to the motor, I know, but there is clear line of site underneath the lower unit for the full 'ducer. More importantly, the port side image is the good image, it is the starboard image that sucks, and there is nothing else over there on that side to block/interfere with the signal.

Okay, so from the back. When I first had this problem I thought, hey, my 'ducer probably isn't level. If the right side of the ducer is pointed up, that could explain why that side signal is weaker. So every time I have been out, I have turned the ducer slightly clockwise to get the right side down. Below is how it is currently:



As you can see, the right side is actually down now past level. I took a level out on the water with me today: my swim platform is level on calm water with me on the starboard side like I am driving, and the bottom of my lower unit is level with my swim platform. So in the water, the bottom of my lower unit is level - the ducer is now over-rotated clockwise but the signal isn't any better.

As well, in some pretty big swells (boat listing at least 10-15 degrees to each side) the right signal is never stronger than the left. I tried to get a pic of this, but had restored defaults and forgotten that it turns off taking images when you "Mark" your screen.

Anyone have any experience/ideas what could be the issue here? Sorry for the long post, just wanted to give as much info to anyone that might be able to help as possible.

I'm going to say the ducer is a dud but Wayne or Doug will confirm the problem for you.

I agree that you may have a weak right side SI crystal.

With the right side lower than the left side, that should be the brightest.

Can you cross-test with another SI unit to confirm it is the transducer?

Wayne,

Do you think it would be more telling to test my head unit on someone else's boat or their head unit on my boat? or maybe both?

I made sure to use 12ga wire for the power extensions since I have to route that a ways. I also kinda figured if it was a power issue both sides would have weak signal.

Not particularly looking forward to ripping everything out for a new transducer install, but I'll suffer through it if that is the real cause.

Yes, doing both would be the best test.

I have been having this same problem. I installed the unit in November and it was working good unitil 3 weeks ago, that is when this shot was taken:


Then this last Saturday, I got this:


I don't have a way to swap out the unit, is there any other way to check this?

I do have a pigtail with two transducers connected - the side image and a 2d for when I am on plane. HB told me to bypass the pigtail, but it seems unlikely a pigtail could go bad in that short a time.

That looks a lot like what I have been seeing Richard, though obviously on the other side. Your top image captures very well what happens to my unit when on a soft bottom.

I would say if you have gone through the same checklist that I have gone through, our problems are very similar. Those are the things that I see get asked all of the time by Wayne, Doug, and others - basically is the unit level and does it have an un-obstructed path for the beam in both directions.

For my situation, obviously there is no obstruction on the right side, is your left side clear when viewed from the side? If so, and you have played with leveling it, I would say you might be seeing the same issue, just with the left crystal.

Richard, your last Sat. image is after you installed the 6.600 and you have the DI Enhance Sharpness turned on. That is one of the glitches with that software version. Don't use that setting until that is fixed.

Yes some issues could come from the AS SIDB Y cable that is why you were asked to disconnect it and just have the SI transducer connected to see where the issue is (transducer or Y cable).

Wayne, thanks for the info.

Do I just turn off the DI Enhance Sharpness or should I reinstall an earlier version?

I will try the by pass this weekend.

As far as I can tell, I am unobstructed to both sides. I don't have a jack plate, but the transducer line of sight is below my motor.

Just don't use DI Enhance Low, Med, or High.

I got the same with one of my 1198c SI units that I installed 6.600. I still have 6.490 in one of them.

Makes sense and explains why the interference showed up suddenly. I'll try it and see - I may reinstall the previous version to avoid any other problems.

Thanks for the help

That is not interference, it is screwed up processing by the new software.

When I was doing the testing for the 6.600 last week, I had my other unit beside it using 6.490. One transducer on the trolling motor and the other on the transom. I used the same settings and none of the DI Enhance Sharpness settings with 6.490 did that and all of the DI Enhance Sharpness settings with 6.600 did it.
This is the High setting:


This is the High setting with 6.490:



Additionally the processing of 2D sonar is different too. Both units had the same 2D settings and the bottom echo colors are slightly different.

try restoring defaults and reinstall latest software

then see about swaping head units with someone else to test.

3rd would be ducer issue.

My 987 was like that with one side dark. Took my head off and put it on my buds boat that has a good working 998. Took his boat out, worked like a champ and verified my transducer is bad.

You can call Customer Service and send transducer and head unit in for testing. But like mentioned simpler to cross test transducer and headunit with another system and test theit head unit on your transducer and your headunit on their transducer that will tell you very quickly where the concern is. Maybe someone on here would meet to help you.