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Old 08-03-2020, 05:48 AM   #1
RocNYRunner
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Furrion DV3100 works without ground!

I'm in the process of adding a switch to the radio to eliminate the power draw while I'm boondocking.

There is a 12v cable feeding the radio from the fusebox. The positive wire is connected to the "memory" and "12v Ignition" wires on the radio. The negative wire is connected to the "negative ground (black)' wire on the radio. My plan was to put the switch on the negative wire, just for ease of only having 1 wire to deal with. Much to my surprise, the radio stayed on after I cut the negative wire. Seems like this shouldn't be possible... Thoughts?

The unit is sitting on the shelf next to the hole where it goes, so chassis isn't grounded to anything.

The antenna is just a coiled up wire, not attached to anything on the chassis.

Speakers are still hooked up, but I can't believe that would be the source of ground.

I knew I should have paid more attention in Circuits...
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Old 08-03-2020, 06:58 AM   #2
JRTJH
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Probably grounded through a speaker ground or through an auxiliary ground.
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Old 08-03-2020, 07:09 AM   #3
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Has to be a ground "somewhere". If the radio is connected to the television either with RCA or HDMI cable I would suspect that's where it's picking up the ground.

Id's suggest using a double pole single throw (dpst) switch or as you are going to completely remove the radio from power just take the ACC feed to the radio to power a single pole switch and attach both acc and memory wires to the switched side.
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Old 08-03-2020, 07:52 AM   #4
RocNYRunner
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The RCA video cables are still hooked up to the TV. That's got to be it! I'll test the theory when I get home from work tonight.

That's the path I'm headed down now, I'll just switch the positive going in.

I've officially stopped lurking and am starting to tinker. Lots of good stuff in this forum, you guys are great!
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Old 08-03-2020, 08:07 AM   #5
flybouy
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Quote:
Originally Posted by RocNYRunner View Post
The RCA video cables are still hooked up to the TV. That's got to be it! I'll test the theory when I get home from work tonight.

That's the path I'm headed down now, I'll just switch the positive going in.

I've officially stopped lurking and am starting to tinker. Lots of good stuff in this forum, you guys are great!
"Tinkering" can be very educational. Most "Inexpensive" electronics use a chassis ground for the input/output connections. "Back in day" when I first became interested in high quality audio equipment you had to have an "isolated" ground on the phono (those large round black discs with squiggly lines for you digital folks) to keep it from creating a hum at high outputs. They used to sell "ground loop isolators" for that same issue.

O.K., reminiscing time is over.
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Old 08-03-2020, 06:00 PM   #6
RocNYRunner
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It was the RCA cables. Unplugged them and the radio powered down.

Put it back together and installed the switch on the positive side. All set!
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Old 08-04-2020, 03:45 AM   #7
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Quote:
Originally Posted by flybouy View Post
"Tinkering" can be very educational. Most "Inexpensive" electronics use a chassis ground for the input/output connections. "Back in day" when I first became interested in high quality audio equipment you had to have an "isolated" ground on the phono (those large round black discs with squiggly lines for you digital folks) to keep it from creating a hum at high outputs. They used to sell "ground loop isolators" for that same issue.

O.K., reminiscing time is over.
I still have one along with an open reel to reel

Oops did I reveal my age?
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