GP1971F Flickering

[Bfrench7]

Recently noticed the FishFinder screen on my 1971 is flickering pretty consistently.

It’s pretty noticeable. Of special note, the GPS/Map view does not flicker. It’s only the fishfinder view that flickers. It is paired with a TM185M and the unit is set to B175M as instructed by Furuno.

I have verified connections are solid and voltage is steady. Ground is good.

I’m at a loss because it only flickers on the fishfinder screen. Makes me think the transducer is causing it.

Any help would be appreciated.

 

[Bfrench7]

After doing some research and troubleshooting, I may have self diagnosed my issue to be a bad connection with the “drain” or shield wire. This was just overlooked during my recent rewire.

I will advise if it solves my issue as soon as I can test.

 

[Johnny Electron]

Hopefully you find that is the problem. I have also seen this if the drain wire is not proper.

 

[Bfrench7]

Hopefully you find that is the problem. I have also seen this if the drain wire is not proper.

Test run this past weekend and the flickering remained...

I already moved and improved the ground, checked voltage (steady) and shortened the power/ground wires as much as possible for the run.

Any thoughts?

Ps. Just to reiterate, the flickering is ONLY on the fish finder screen, not on any other screen.

 

[Johnny Electron]

Do you have any other lighting on at the same time? Sometimes the hz rate of the lighting can conflict with the scan rate of LCDs and make your eyes see a flicker. If not, then I recommend you take a short video and open an official support case with your local Furuno distributor. The only case I have seen was flicking on map screen and it was because it wasn't grounded via the shield wire as shown on page S-1. A video will be a big help for support to have an idea what the problem might be.

 

[Bfrench7]

No lighting running, just natural sun light.

I will try a video and get it over to support. I tried moving wires and checking for interference. The wires are about as isolated as they can possibly get in a confined space like a center console. The transducer is also run through its own rigging tube.

Thanks

 

[Bfrench7]

It's been a minute, but here is an Update to this issue.

I isolated the circuit and ran a dedicated circuit to the fish finder. To my delight, the issue disappeared. So, in an effort to better understand what was causing the issue, I moved the circuit back to it's original location and began removing grounds for other accessories one at a time from the BUSbar. When I removed the ground for switch panel backlights, the flickering went away. Still a little baffled by that one, but, I can't argue with results. I moved the ground for the backlights to a different grounding location and everything has been solid since.

 

[Johnny Electron]

Lighting on boats especially LED lights are known for back feeding noise. Really nice troubleshooting. :jump

 

[ivansfo]

I am experiencing the same flickering on my 1971F. Firmware version 4 with a P66 transducer. Like the OP, it only flickers on the FF screen. Chart screen looks nice and stable.

A little background. My first1971F was installed 3 years ago with a P66 connected. It ran beautifully with no flickering. In spring of 2022, I added a 2nd 1971F and moved the P66 transducer to this new plotter. The FF screen now flickers on the new plotter. There are no other transducers on the boat. Only the ground wire and +12v are connected.

Some things I've tried which did not help.

1) Shut off the engines.
2) Turn off the other 1971F
3) Disable TX on the FF on the other 1971F (even though there is no transducer connected)

Both 1971Fs are connected to the same ground bar and same +12v circuit. Is it possible that the other 1971F is interring? I have yet to move the P66 transducer back to my original 1971F and this is my next plan in troubleshooting.

 

[Johnny Electron]

You can alway try running it from a separate linear power supply for testing or send the unit in for evaluation. If the ground wire is properly grounded to a bonded system, the input power likely has some AC running on on the DC power. You might consider a power conditioner.

 

[ivansfo]

Hi Johnny,

Good idea on isolating the new 1971F to a separate power source. I'll temporarily move power connection to a portable 12v deep cycle battery to see if the flickering persist.

The shielding of the power connector has a drain wire. Is there a recommendation about grounding this drain wire too? The boat is a 23' fiberglass boat by Boston Whaler where the ground bar connects to the battery negative terminals.

Thank you.

 

[Magnetron]

The shielding of the power connector has a drain wire.

This is probably the real root cause of the issue,

That is - residual static electricity that builds up as you pass through water needs a place to "drain out." I might consider looking into installing a dyno plate or "ground plate" and attach it to the bottom aft of the boat which will serve as the best 'earth ground' you can get, boatwise. Than start routing these RF drain connections to that plate with 20-22AWG. This'll probably clear up a lot of noise issues if you had any.

Just a thought, :sail

- Maggy

 

[ivansfo]

Thank you Maggy. I will experiment with the drain wire too. Looks like I joined the 2 drain wires together between my two 1971Fs. Will try separating them and see if that could resolve this too. I hope I don't need to install any kind of dyno plate outside of the hull.

 

[Magnetron]

I joined the 2 drain wires together between my two 1971Fs. Will try separating them and see if that could resolve this too.

Prudent, the manual says the shield goes to a ship's ground and not to another GP1971F or to another device.



If someone shuffles their feet over a carpet, sure they can just touch someone on the nose (i.e. ground shields that are wired together) and discharge that static electricity! ouch :angry or they could touch something grounded to earth .

One method is no big deal, but the other is very shocking.

I hope I don't need to install any kind of dyno plate outside of the hull.

Well, without a plate we're depending on this ground you are using at the moment. Where does this ground go? the chassis? is part of the chassis touching the water? If it doesn't, than static electricity goes everywhere shocking all the devices attached to that ground point effectively turning a RF Ground into an antenna. :noway

We would highly recommend considering a dyno grounding plate and a grounding bus bar strip, where each RF ground would go on a spot on the strip, and the strip grounded to the plate for any large or small boat for the BEST performance.

Hope this clarifies, :sail

- Maggy