Video interference problem

[J.REEVES]

I have just run new 4pin cable from the front of the vehicle to the rear 12pin plug for my camera on the rear of the van.
This is the cable I used: http://www.ebay.com.au/itm/271309040992

I use some of the pins on a 12pin plug to transfer the video signal from the van to the vehicle which was the same on my old vehicle.

The camera and monitor work OK but if I operate the brakes or the blinkers I am getting interference a bit like bar lines on the monitor.

This new cable has four wires and the outer has a shield like coax but the shield is not earthed and is only very thin aluminium foil that thin if you try to earth it, it just disintegrates.

It appears that the DIN fittings that are at each end of the cable are not earthed to the shield.

I never had a problem with my old vehicle but the video run was in shielded coax.

Would it be fair to assume the problem is due to poor quality cable and should the shield be earthed?

JR

[Old Techo]

JR,

I would hope that the audio and video cables have their own individual shielding, like coax, and connected to pin 2 especially if the outer ally shield is floating.

Thin ally outer shielding is common with cables. You could try a test earthing with an alligator clip clamped on the shield. You could also make a permanent earth wire from bare single stranded wrapped around the ally several turns then twisted tight. Solder a flexible earth wire to the twist.

I am trying to figure the source of the RFI you are experiencing. Perhaps the 200 generates much of that stuff?

Was there any such interference without the cable connected to the monitor? How is the monitor powered?

[J.REEVES]

Hi OT, I was hoping you would be around.

The four wires are not shielded, the only shield is that outer aluminium foil. Pin two is just running an earth to the camera and is not earthed to anything other than back at the start of the run where I connected it to earth.

The sound is not in use only the video.

I had a hell of a job to get this bloody wire through and am panicking a bit thinking I may need to run something better.

You have already made a few comments that may help about the outer shield may not be earthed and this cable is made for this job so maybe it does not need to be earthed.

The Monitor and its Black Box:

monitor.JPG

The monitor is feed via a black box with power video and audio going to the monitor from the box and two video inputs to the box and three wires from the box two of which are power and the third is to the vehicle reversing switch which I don’t need.

No interference with the monitor disconnected from the camera input but I may check that again.

When I connected the 4 pin cable at the 12pin plug I added an extra earth on the same pin so I will disconnect that to start with and see what happens. May even disconnect the video cable earth (pin 2) at the 12 pin plug as it is only going to the van camera which already has an earth.

I did try rapping a fine copper wire around the aluminium foil but it does not seem to make a circuit as the foil has some kind of bluish lacquer on it and it will not come off without the stuff falling apart.

When the brakes are operated the Redarc brake controller outputs so that will not help as it is run in the same conduit. The blinker lights are separate and they also interfere with things so something else is at work.

Now I have had a chance to look at the whole picture my only chance could be too many earths on the same plug pin.

JR

[J.REEVES]

Four hours of trying to solve the video flicker problem and I have accomplished nothing!

Ran good quality coax from vehicle van socket to monitor no change with van plugged in still flickers when brakes applied.

Connected a spare camera to the rear vehicle socket with no van connected no flicker but with van connected flicker as before using the spare camera and not the van camera..
For some reason when the van is connected the monitor flickers whenever the brakes or blinker lights are operated.

I think I have proven that the 4 pin cable is not the problem.

For some reason when the van is connected I get the flicker but the old setup never did this so maybe this new monitor is super sensitive, it is a 16:9 instead of a 4:3 aspect ratio and also the resolution is higher. It does display a better picture than the old monitor until I touch the brakes.

The coax run in the van is quality coax so the only place interference may be occurring is at vehicle/van socket and plug but this has never been an issue before.

JR

[dieseltojo]

Hi JR,
It brings to mind that others have had video problems when they had Led lights playing up.
Just saying....

[loub]

Hi JR.I have a Polaris camera ect on the van and when my auto electrician did the job the camera is connected with a separate 4 or five pin plug which has the a female plug on the van and one on the car and i have a male lead that plugs both together.No way can it pick up interferance as is an inderpendant circuit powered from the main battery. Peter

[muzz_on_line]

Hi JR,

As dieseltojo alluded to, does your car have an extra harness fitted that caters for led trailer lights?

If so, I would have a look at isolating that to see if it is the culprit.

Another thought is can you check whether your electric brake controller sends out any pulsing (to check that a trailer is connected). I know my P3 senses the connection.

Cheers

Muzz.

[Old Techo]

JR,

Sorry, I've been a busy.

When you first reported the issue the brake interference was more explainable but the blinkers were and still are hard to explain.

The brake controller has a greater capability to generate interference as its nature is to rapidly switch high currents. Six amps for a single axle and 12 amps for a tandem. I reckon the level of interference would not change much from light braking to heavy braking as the same number of 6 or a12 amp transitions apply and only the 'on' time gets longer with heavier braking.

When the van is not connected the brake controller is not switching any current.

How far is the brake controller mounted from the monitor?

I specifically asked you in my first post whether the monitor exhibited interference when the 4 pin plug was disconnected. Cables connected to the monitor could act like antenna. I also wondered then about direct radiation from the brake controller.

I also asked about how the monitor was powered as interference could get in via the power feed. I see though the power feed claims to have a filter.

The blinkers can also switch significant current if the van has incandescent lights but only 1 pulse per blink whereas the brakes may be a hundred or two pulses per second. That's a guess based on the sound made. Are the 2 types of interference quite different?

[J.REEVES]

Thanks everyone for your input, every suggestion has been noted.

Yes the new Tojo has one of those boxes for LED’s, the box is more to send decent signals to the van as the Tojo has all LED’s.

The brake controller is under the dash right next to the Monitor filter box. The brake controller is a Redarc so the control is just a knob on the dash but the main bit is near the Monitor power and filter and video input plugs so could be an issue.

I am using the 12pin plug to connect the video from the van to the vehicle as before but this could be my problem.

I have a separate power supply to the monitor and that then feeds to the van camera.

OT when the video input (4pin plug) to the monitor is disconnected and the brakes are applied there is no sign of any interference on the monitor which displays a blue screen with no video input connected but the van is still connected so the brakes would be pulling current as you described.

Yes the two types of interference could be said to be different. I will take some photos tomorrow of the interference.

I must come clean with a third interference that I did not mention as I did not wish to complicate the issue any further but this one is my real concern.

The problem is my van filter pressure blower system which when on dusty roads could be running all day. The brake and blinker interference is not that much of an issue as it only occurs when the item is operated and that’s not for long. Also the monitor display is still OK to view just not perfect but the blower interference is pushing the picture quality down to a point that I need to fix it.

The blower is powered via the Anderson Plug from the Tojo Aux battery and the blower is switched on via a switch in the Tojo which then operates a relay in the van (via 12pin plug) to switch the blower on (4amps).
I have noticed that the blower can interfere with the AM radio in the van so I expect it is producing some bad RF. I may try and attach a capacitor to the blower motor when I find the time. Not sure what size capacitor to use so any suggestions, I expect the capacitors would need to go on the motor brushes to earth.

The van has had no wiring changes and when the blower was operating with the old Tojo the old monitor did not display any interference.

I will try and post some photos tomorrow of the interference on the monitor.

JR

[loub]

JR if the dust fan ends up the issue why not run it from the vans batterys only and cut out the connection to the tug.Peter