How to Properly Tap into a 12V Circuit for TV and Bluetooth Adapter

[matttt22]

Hey guys, I am installing a MBT-RX marine Bluetooth adapter and a 19.5V TV on my 2007 340 SeaRay Sundancer. I have been reading through all of the posts on this form and really appreciate everything I learned from everyone as there is a wealth of information.

However, I could not find anything regarding the "preferred" way to wire into the 12V system. My question here is, how would the professionals do this?

Q1: 12V MBT-RX marine bluetooth adapter - There is a harness going into the radio and a 12V lead going to the 'stereo' breaker. To keep it on the stereo circuit, can I simply cut the harness 12V wire and and splice into it using butt connectors?

Q2: I have a 12V RECEPTACLE/TV breaker that doesn't actually power the LG 32" TV that (I believe) was factory installed. I THINK (I need to check) this breaker goes to a TV in the aft cabin (below the TV in the picture). Ideally, I would like to keep both TVs on the same circuit (I know I need to check if the breaker can handle the load if they are both working). For this should I also just run a splice from the existing circuit?

Factory installed? TV

Breaker panel:

 

[Wylie_Tunes]

Q1) The BT receiver needs to share the same battery voltage reference/source as ALL the other audio equipment in order to prevent unwanted noise. So the new BT needs to draw its 12V B+ and B- from the same source as the main media unit and any external amps. Where to make this termination? I would avoid cutting a wire so to avoid creating an unwanted new splice/joint.

Q2)/ Most TVs are are 12V once the juice gets inside. Some, like a home TV use a 120 AC to 12DC converter while some geared towards recreation use are 12V ready, meaning they do not have a converter and are ready to wired direct to a 12V DC source. If the TV's sound output is going to be pipped to the boat's stereo system, then the TV now needs to share the same 12V source as said stereo system.

 

[matttt22]

Q1) The BT receiver needs to share the same battery voltage reference/source as ALL the other audio equipment in order to prevent unwanted noise. So the new BT needs to draw its 12V B+ and B- from the same source as the main media unit and any external amps. Where to make this termination? I would avoid cutting a wire so to avoid creating an unwanted new splice/joint.

Q2)/ Most TVs are are 12V once the juice gets inside. Some, like a home TV use a 120 AC to 12DC converter while some geared towards recreation use are 12V ready, meaning they do not have a converter and are ready to wired direct to a 12V DC source. If the TV's sound output is going to be pipped to the boat's stereo system, then the TV now needs to share the same 12V source as said stereo system.

Q1) Can I simply terminate it into the stereo breaker if there is enough room on the breaker itself? I am not sure if this is allowed/best practice for low voltage. This way I wouldn't have to splice.

Q2) Note, the new TV will be standalone and not hooked up to the stereo system. However, I am now wondering... can I add a 12v to 19.5v step-up converter to the same circuit that has a 12v tv? If not, I may just get rid of the 12v TV completely.

For example: Would this be valid?

Thanks for your help!

 

[matttt22]

Q1) I think I may have already found my answer. I probably should have mentioned this earlier, but my radio is the Clarion CMD4. I just took a look at the wiring diagram on the CMD4 and it looks like there is already a lead for 12V accessory with a 1 amp fuse.

The JL Audio MBT-RX already has a 2 amp fuse on it, but it also looks like the max power draw is 32 mA (at full output) according to https://www.jlaudio.com/products/mbt-rx-marine-audio-bluetooth-receiver-91126.

So I should be able to wire it directly to this lead coming off. However, I do have a 6 CD changer installed and not sure if it is already wired to this lead. I will need to check when I am in the panel again. Either way, I should be able to splice from this wire (if the CD player is getting power from this lead) or just disconnect the CD player entirely.

 

[Wylie_Tunes]

The red wire is a switched 12V turn-on, so you would not want to use it for the BT. The yellow MEM/CONSTANT is the proper circuit.

 

[Wylie_Tunes]

The yellow wire is the input power to the amp.(direct to battery this keeps all your presets and time and settings ect.)
the red is supply for accessary (doesn't say it is switched). If your NOT using the amp as a sound source.(Using the internal speakers) then just you the tv breaker.

Lets start with the yellow. The Clarion CMD WILL NOT FUNCTION without the yellow wire supplied with 12V. This is the circuit that the unit actually draws its operating amperage from. Its typically connected direct to a battery source because the CMD did not yet have non-volatile onboard memory. So if you wanted to retain memory, this circuit did require a constant B+. If you did not need to retain memory, it can terminate on the boat side of the main switch or a helm switch. I have no idea what you mean by amp or internal speakers when you referenced the yellow circuit.

Now the red. The Clarion CMD unit WILL NOT wake up unless there is 12V on the red circuit. This circuit is often switched by the ignition key switch or a helm rocker as a means to turn the CMD on/off. However, the red can be terminated with the constant yellow. But in doing this, you now have to use the CMD's power button to turn the unit on/off. I do not suggest wiring the red to the yellow as this makes it too easy to walk away leaving the stereo on. I also dont like the red on the IGN key. I often times relocate the red to an unused rocker switch. Especially on a wake sports boat where frequent engine cycles occur. Other wise, every time you shut the engine off, that short loss of voltage between RUN and ACC key position, is enough to cause the stereo to shit down, resulting in having to re-pair/restart the streaming music.

I certainly hope you are not suggesting the OP connect the BT's B+ to the TV circuit? This will almost certainly result in ground loop noise.

 

[hynespa]

Hey @matttt22 - I converted my Samsung TV to run off of 12v instead of 120. I detailed it here (not sure why the pictures I took are not coming up on the site any more):

420 DA Thread

We are excited just closed on new to us 2007 44 Sundancer.Will be running her from Ft Lauderdale this Saturday to our home port Punta Gorda Fl. I see you have a hydraulic platform with jet ski (I do too), this will also change your loading significantly. You have 500lbs lift plus approx...

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