Topic: 798ci HD si lose sonar reading when hot.

[LLCC]

Hi all, awesome forum. There's so much to learn from this place. Thanks for writing up all these good advise!

I've just started to use my 798ci HD si and it runs OK (or with my limited experience with this set, it seems ok to me). But after recording for around 3 hours without cover from the sun, I'd lose all sonar readings, the depth reading blinks at the last reading it was bottom locked to and the control head feels hot. I could not get the sonar to read, although the unit was still recording the tracks and the speed displayed is ok. Only when I shut down the unit and give it some time to cool down will the sonar start reading again.

So far, this has happened to me on 3 separate occasions out of 5 trips out with the unit. On the 2 trips out at night, the sonar recorded through the whole 6 hour trip with no problem.

Is this a problem with the unit or a feature for overheating protection? BTW, the air temperature was around 89°F and water temperature 20° F. Doesn't seem to be too hot for the unit to fail in operating.

Your thoughts appreciated!

Best,

Lawrence Lee

[Roddy]

LLCC, 89'F not seam to hot for the unit. Hear in Charleston SC,USA it can get to 110'+ sometimes and I have not had any heat related trouble.

With the the flashing depth reading try resetting BOTTOM LOCK to AUTO or MAMUEL and check all electric connections.

Good luck and enjoy.

Roddy

[Humminbird_Greg]

It’s not just the ambient air temperature that you have to consider here, it is also the exposure to direct sunlight.  I have some experience in product testing and measuring the internal temperature of our units when exposed to different temperatures both in and out of the sun and believe me – full sunlight makes a big difference!


It does sound like your particular unit may have a heat related problem Lawrence.  Be sure it is not a power related problem though by ensuring that you have a good clean power connection all the way to the battery and that the battery is in good condition.  Ideally you want the unit connected straight to the battery (through an in-line fuse) with a heavy enough gauge of wire.  I recommend at least a 14 AWG multi-stranded copper wire if you have to extend the power cable by more than 5 feet and that all connections are soldered and sealed against water and moisture.  I would also have the battery load tested as it could show a 12+ volt output but not have the current capacity to back that voltage up for the unit.

If the electrical supply checks out well, you can try testing your unit on another boat under the same conditions and see if it fails there as well.  This would definitely determine where the problem is.

[LLCC]

Thanks for your replies Roddy and Humminbird_Greg.

Here's what I had done when I lost bottom reading and the depth reading flashes:
1) Changed bottom lock from auto to a depth double the true depth (average depth is 10')
2) Turned off sonar and turned it back again.
3) Took transducer out to make sure it is not fouled
These didn't help at all except for turning off the unit till it was cool to the touch. (The unit casing was rather hot to the touch when the problem surfaces).

Greg, the unit is directly connected to a new dedicated battery that is fully charged. Head Unit to battery cable length is only 2ft (It's a small portable boat). I'll monitor the situation again to see if there are more signs that point to overheating. Maybe I'll make a little shade for the unit to see if it is the effect of direct sunlight. Incidentally, the bezel around the display seems loose enough that it squeaks when I press it. When connected to the mount, pressing it will cause the unit to go blank. Since starting up again was no trouble, I didn't bother much with that.

I'll test the unit for a couple more weekends and then report back here.

Best,

Lawrence

[ITGEEK]

LLCC,
Just because your battery is new, it doesn't mean it's any good.
It could have set on a shelf for a long time before you bought it.
The only way to be absolutely sure it's good is to load test it.

[LLCC]

Hi, reporting back after a few rounds of testing.

Here's what I did:
1) Ran the unit 5 hours off a freshly charged battery in the cool of the night. Battery is also used to power the navigation light. No problem with losing depth readings/overheating.
2) Ran the unit 6 hours on a cool windy and cloudy day, same battery recharged. No other devices connected to battery. No problems.
3) Ran the unit on a hot cloudless afternoon. Same battery recharged. Lose bottom reading after 2 hours. Turned off, restarted when unit was cool and ran under a shelter to shade the unit. Gets hot to the touch but no problems running 4 hours continuously. Water temp was around 86°F on this day.

Is this normal?

I forgot to add that each time I push the head unit at the top bezel (where the humminbird logo is) to tilt the unit skyward, the unit will lose power. Restarting is not a problem, it starts up again as normal.

Any thoughts?

Best,

LL

[ITGEEK]

It sounds like you have a loose or questionable
power connection.
Try bending the pins on the power cable out a little
(DO NOT TOUCH BOTH PINS AT THE SAME TIME WITH A METAL TOOL
OR YOU WILL BLOW A FUSE).

[Humminbird_Greg]

It does sound like the power connection is a little “iffy” but I don’t know that it would cause the unit to cause the unit to lose the bottom reading without also shutting the unit off.

[LLCC]

Hi all,

Updating on the problem after some time testing.

I did not dare bend the pins in the power cable as they look too thin and fragile for my clumsy hands. However, I did find that the power chord rattles a bit in the mount. So I removed the mounting plates and there was this stainless steel plate with a myriad of shapes stamped. I figured they were a bit loose, so I bent the shape that corresponds to the power chord plug so it push the plug tightly against the mount.

Went out and tried it, running overnight and no problems with the unit turning off nor losing bottom reading.

Now I can look into playing with the settings so that I can see something with Down Imaging.

Thanks for all your guidance!

LL

[wpda]

MY GUESS IS A FAULTY TRANSDUCER
DO YOU LOSE ONLY THE DIGITAL READOUT/ FLASHES WHILE RETAINING GRAPHICAL READOUT
TRANSDUCERS HAVE BEEN KNOWN TO CAUSE THIS IN THE PAST

[LLCC]

MY GUESS IS A FAULTY TRANSDUCER
DO YOU LOSE ONLY THE DIGITAL READOUT/ FLASHES WHILE RETAINING GRAPHICAL READOUT
TRANSDUCERS HAVE BEEN KNOWN TO CAUSE THIS IN THE PAST

I lost both digital readout and the screen draw freezes for bottom reading. However, the GPS readout still worked.

I believe mine is traced to high temperatures as I do not have this happening when I use it through the night.

LL

[Humminbird_Greg]

Lawrence are you still having problems with your 798ci HD Si unit?

FYI: If the unit loses the digital depth reading it will pause the bottom display as it searches for the water depth.

[LLCC]

Lawrence are you still having problems with your 798ci HD Si unit?

FYI: If the unit loses the digital depth reading it will pause the bottom display as it searches for the water depth.

I've been using the 798 ci hd SI at night, so I didn't have any problem with losing depth reading.

Now, I'm trying to figure why the pier piles appear slanted inward on SI. I've posted a separate thread on that.

[Humminbird_Greg]

Okay, let me know if it starts acting back up when you fish during the heat of the day (if it is still hot over there during this time of year).

I saw that post and agree that the posts themselves must be slanted.  If it was the transducer angle they would both be slanted in the same direction and there are no menus that would cause this.

[LLCC]

It's been raining heavily and I dun have a chance to go out.

LL