How “clean” is the power output from the Lightning outlets? Pure sine vs square waves

[Citizen0]

Hi everyone. A couple of weeks ago I went camping and was responsible for movie night. This was in a field away from any power, so Sparky (Lightning Lariat ER, antimatter blue) was the PERFECT solution.

Movie night isn’t my first rodeo. I have a 16’ x 9’ outdoor screen, an Epson Laser projector and a Sony receiver with 4 outdoor speakers. The receiver is what I use at home for my TV. I’ve never had any issues from any of these components.

The day of the event I got everything setup, powered up the truck and started the movie. The projector fired right up as did the receiver… with a problem.

There is a very loud humming when I have the Sony receiver connected and powered on. The initial test went well, but during the movie if there was any extended loud scenes or if I had the volume “too loud” the receiver would go into an overload mode. This does not occur at home at the same volume.

My only guess is that the power from the outlets is not a clean sine wave and may be the more dirty, but generally acceptable square wave that many inverters output?

Has anyone had any experience like this or have any suggestions? I will be doing movie night in the future, so I want to get this fixed. My first thought is to add a power conditioner or UPS to clean up the power before it gets to the receiver, but I’m somewhat confused why the power output would be dirty in the first place unless it was never intended for “sensitive” electronics.

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[wilmerfjohnson]

Audio hum is sometimes caused by a ground loop - not necessarily a fault with the AC power. Some audio equipment has a terminal on the rear that you can disconnect to eliminate the ground loop. This can happen on equipment powered by AC mains (i.e. your home's power.)

 

[Citizen0]

Im sorry, I wasn’t very clear in the original post. I’m familiar with ground loop hums.

The humming in this case is from the receiver itself, not the speakers. The actual audio is perfect. But something about the power from the truck trips the receiver whenever it draws above some unknown threshold of wattage.

I have to get this fixed as I’m pulling a parade float the 8th of October that will have sound. Next tests will be with a different receiver and then throwing a UPS in between the truck and receiver.

 

[Amps]

Next tests will be with a different receiver and then throwing a UPS in between the truck and receiver.

A true sine wave UPS would be my first shot at fixing it, too.

https://www.costco.com/cyberpower-1...ble-power-supply-(ups).product.100527623.html

 

[metroshot]

Have you checked for EMI/RFI that might be getting introduced by the Ford's onboard switching power supply ?

DC-AC conversion usually requires multiple clock signals to step the voltage to a sine wave.

If the conversion clock is creating a field, you may want to try moving the receiver further away from the truck.

I'd also try some ferrite EMI/RFI filter donuts to wrap your power supply cables around to filter some noise.

Lastly, I would try out a UPS with sine wave output.

I have various commercial / enterprise units I may have to try out - APC, Cyberpower, Eaton, etc...

 

[Citizen0]

Good idea to try moving the receiver and adding ferrite cores!! That would definitely be the least expensive option!

I’ll try each of these suggestions over the coming week and get back with the results.

Thanks everyone for the help!!

 

[FlasherZ]

I have an old isolation transformer that I use when I encounter these types of things, it filters the power and isolates the ground to clean up the signal. It was especially important when I was restoring some old 35mm film equipment with the old-school optical sound heads, because there are unintended grounding issues all over the place.

 

[V8BoatBuilder]

FYI, I put my oscilloscope on the truck after reading this thread. Not sure why you were having issues, as I got a great result.

https://www.f150lightningforum.com/...e-wave-inverter-and-the-power-is-clean.12705/

@Citizen0 - how many amps were you pulling?

 

[Snappy22]

Good idea to try moving the receiver and adding ferrite cores!! That would definitely be the least expensive option!

I’ll try each of these suggestions over the coming week and get back with the results.

Thanks everyone for the help!!

Any update?

 

[Citizen0]

Yes! I think the problem was with the old receiver. It is probably... close to 20 years old. My newer Onkyo had no issues whatsoever in the parade. I never saw more than 300w from the outlet.

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