Ground loop problem?

[carbongixxer]

Smanches, so do you think I should just go ahead and replace that 16v 470uf capacitor with 2 25v 1000uf capacitors?

 

[Hayato]

With this chip the only external parts you need are the two filter caps and an inductor. It's about the most simple SMPS you can build. If you were to build it from discrete components, there would be much more to do.

Most likely, the chip is not behaving exactly as expected and has more voltage ripple than the video system can tolerate. Adding a newer larger cap, or an additional cap (on the output) could help a lot.

Hayato: I know it's there. I'm not sure what you were pointing out? I was talking generically about the chip itself, not the specific charger.

Ok, sorry for that.

Carbon, keep the 100uF 35V (if it is not bad).
I saw a diode on the picture, test it too.

 

[mneary]

Where do your cameras get their power? Is there any way to provide their power through the same lighter socket?

 

[carbongixxer]

Mneary, the cameras get their power through the quad processor unit. The quad processor unit has a single power wire coming out to cig lighter. I have tried wiring both the charger and processor together, but still the lines show.

Smanches, so do you think I should just go ahead and replace that 16v 470uf capacitor with 2 25v 1000uf capacitors? Should they be wired in parallel?

 

[carbongixxer]

I tired placing 2 25v 1000uf capacitor inline, but the lines are still there. Does this mean its interference? What do you recommend i try next?

 

[Hayato]

What do uou mean by 'inline'? If they are in series, then you just got 500 uF.

 

[Sceadwian]

You should probably rewire all the AV equipment to use a common ground point to the frame of the car like a standard star grounding topology does. A cars electrical system was never meant to run AV equipment like this.

 

[carbongixxer]

I meant inline before the charger plug, so both caps were parallel.

Sceadwian: what do you mean by a standard start grounding topology?

 

[Sceadwian]

Star ground, all of the devices that have anything to do with the AV system would have to be connected to a SINGLE point on the car frame, not at different locations, that's how ground loops happen.

 

[carbongixxer]

I tried to wire the charger and the camera processor together at the same point, but there was still hum lines.

 

[carbongixxer]

Could this mean its interference and needs some sort of suppressor?

 

[smanches]

Have you ever gotten it to run without the lines? Almost starting to sound like a bad unit itself. 2000uF should have gotten rid of any ripple from the supply.

Could be interferrence, but I doubt its from the car. Do you have to have your ignition key on to get power out of the cigarette lighter, or is it powered all the time? Can you find a different 12v battery to power it off of?

If it always shows the lines, even when powered from it's own 12v battery, then there must be something wrong with the unit.

If you have gotten it work work without the lines, then start there and work backwards until it breaks. Then find a workaround for that particular problem.

 

[carbongixxer]

It has always had the lines when I connect the charger. Its connected to a always on cigarette lighter.

The 2 1000uf caps should be wired in parallel, correct?

 

[smanches]

It has always had the lines when I connect the charger. Its connected to a always on cigarette lighter.

The 2 1000uf caps should be wired in parallel, correct?

Yes, that would give you 2000uF. I'm at a loss now. Sounds like a fault in the unit.

 

[carbongixxer]

I feel like its making a ground loop because I'm connecting power to the charger which connects to the recorder and then a separate power source going to the processor and in which the processor connects to the recorder.

 

[mneary]

Have you tried a big capacitor (one of the 1000µF) on the input side of the charger?