(SOLVED) Viofo A119S video banding/sound noise issue

[cra3y]

Hi

I just mounted A119S on my VW Polo 6R.

There is something wrong with electromagnetic shield in this camera. I mounted new wire and power supply (which was included in the box), switched power on and strange visual and sound noise appeared after a while.
The noise was worse, when there is low light.

Then I replaced I reused my power adapter from my previous dashcam (which works great) and no difference.

I suspected incadescent light as source of electromagnetic issues, so I tested again today. I has commuted to work and still no difference.

Is my camera faulty?

 

[NI_DashCam]

I looks like either a bad power supply or a bad earth connection.
I had something similar on another camera when using a hardwire kit, went away when using a different supply.

 

[cra3y]

I tried second power supply and result is the same. The last suspicious thing is USB cable (I will test it today).

PS: I wonder, what kind of device (in car) cause such electromagnetic noise.

 

[flip9]

If you have a GPS mount, try without it.

 

[Dashmellow]

Is the USB cable shielded? Non-shielded cables or poorly shielded cables can be prone to electromagnetic noise and RFI. I know there are more reports of this kind of thing with GPS enabled cameras.

 

[NI_DashCam]

Here is a video of the noise that I had on a mini 0805. Used a different power supply and USB cable and it has been working fine since.

 

[cra3y]

Ok. I borrowed second A119s and I did some tests and found guilty one

All tests were on car with engine not running, nor other devices (radio turned off etc). The 12V was from accu, not accu+running alternator)

1) I replaced 12V->5V converter into second one -> no difference, still interferences on screen and sound
2) I replaced camera - still no difference
3) I replaced cable - No interference at all!

It sounds interesting, because this cable (the faulty one, shielded) was great in previous CVR-A7810-G PRO and G1WH. I think that it performs well, because the former ones was powered by lithium battery and have charging circuit onboard, which have better filtering circuit than A119S (capacitor based).

 

[mikek753]

thanks for the update and the solution info
Soon I'll get 119S and install it
it's funny as a capacitor, especially supercap has to take care of DC power fluctuations - IMHO
in this case it might be diff kind of interference that capacitor can't address
any one with electronics background can comment? please

 

[Nigel]

You should try and use the cable supplied with the A119S, Viofo have carefully selected that one to avoid problems with interference, it is not just the cheapest one they could find!

Bit surprised to see the result so bad just from a cable though, must be more than just the effect of the shield, looks more like a grounding problem.

 

[cra3y]

Yes, I ended with USB cable supplied with A119S (by Viofo). I was lazy to replace existed cable, but I had to

I think that interference comes from live CAN bus - cable runs along A-pilars (airbag inside) and near by Airbag driver in central console.

 

[Harsh]

Cables can go bad too, below is how the GC started behaving due to a recently installed Amazon basics cable that decided to act up. Switched it with a Monoprice cable and the camera was instantly back in business. With my Monoprice cables here, took this forced opportunity and switched all the AB cables with the new ones.

 

[cra3y]

In Your case it looks like that power wires was to thin - not enough current (amperage) was allowed to flow to device or voltage drop was too big (big cable resistance).

In my case there was no problem with power, but probably bad quality shielding or broken cable shield behave like antenna.

 

[Harsh]

Not saying there's any relation. Just pointing out that a cable that's been working just fine till yesterday can also suddenly go bad.

 

[cra3y]

Perhaps Your cable resistance was close to highest possible to successful deliver enough power to Your device, then the connectors worn over time (copper oxidation, moisture etc.) that causes additional resistance then bam!!

 

[jokiin]

Perhaps Your cable resistance was close to highest possible to successful deliver enough power to Your device, then the connectors worn over time (copper oxidation, moisture etc.) that causes additional resistance then bam!!

a lot of cheap cables use CCA wire not OFC, the cables degrade over time until they start to cause problem

 

[kamkar]

Yeah stay away from CCA cables, its like peeing in the pants on a cold day to keep warm.

 

[Nigel]

In my case there was no problem with power, but probably bad quality shielding or broken cable shield behave like antenna.

Maybe the shield was shorted to the car body somewhere? That could cause a ground loop and big power fluctuations.

Note that the super capacitor doesn't necessarily smooth the power supply in the way a normal capacitor is used, it is more likely that it is used as an alternative power source when there is not enough power from the main source, otherwise it would massively overload the power supply when you first switch on and it needs charging! Also there wont be any electrolytic capacitors in the camera for power supply smoothing that you would find in most devices because electrolytic capacitors suffer at high temperatures. It is the job of the power adaptor to provide a smooth and noise free supply.

If in doubt, use the power adaptor and cable supplied by Viofo.

 

[cra3y]

With new cable I tested 3 power adapters - all worked well.

PS: The faulty cable was not damaged (visually checked) nor shorted to car body.