Constant Power to Stereo

[Reefmagnet]

Originally Posted by a64pilot

That is usually called conformal coating, and is easily ordered on Amazon and or bought in an electronics supply store if any of those exist anymore.
I usually use the brush on kind myself, and conformal coating the boards is often the difference in “Marine” electronics.
Now often times there is an honest real difference in “marine” but sometimes like batteries for instance, it’s just marketing’s excuse to justify a higher price is all.

Conformal coating seems to by used far more often now as SMD's have proliferated and I think this is the reason for the better protection. I do have a can of conformal coating on hand, which I'm pretty sure is just thinner motor winding polyurethane spray but circuit board laquer is different again and is of a formulation that allows it to be soldered through for repairs, hence very popular with the DIY electronics crowds.

[a64pilot]

I use conformal coating, which I think is a pain if your going to do any soldering. There are four types I believe, one is silicone based, I use I believe acrylic type.
Anyone who has never done it, it’s easy, you just brush it on, I use an acid brush and just throw the brush away afterwards.
I’ve not coated all that much, usually things like the smart flush control on our head or the windlass remote I got from Amazon 5 yrs ago that has functioned perfectly. The boards on the Solo waste tank monitor etc.
I don’t do any board repairs anymore, not now, and rarely before.
I took a little 2 oz bottle from work, we got it in 1gl cans, and that I’m sure would last for years.

[danielb]

I agonized over this situation for a while on my boat. I wanted zero draw, as often away for weeks, and did not want to rely entirely on my solar panel.
Ended up finding the Fusion RV-CD850BT. Basically one of their car stereo models, but specially for RVs. Has non-volatile memory like the Sony mentioned here also.
Great stereo, does everything I want, but developed one issue after a couple of years - The rotary encoder (volume knob amonst other things) is a bit flakey and sometimes it dithers a bit (setting goes back and forth, instead of only up or down as intended). Probably just corrosion on contacts. For now just living with it.

One trick I did for with previous boat for reducing power usage while stereo in use:
Bought a small class-D car amplifier and connected to the RCAs of stereo. Opened the radio up and snipped the Vcc+ leg of the MOSFET chip on stereo. The amp chip uses tons of power, especially inefficient at low volume, where most energy is dumped in to heat sink.
...Or pay moon beams for one of Fusions Marine stereos (the little cheaper ones don't/didn't use Class-D).

[Alita49DS]

My error when I referred to my Sony MEXM70BT as a marine stereo without qualifying what it actually really is.

The unit to all intents and purposes looks and functions like a car stereo. It is not designed, as far as I can tell, for use outdoors and it does not have a waterproof IP rating. As it includes a CD slot that would be difficult.

https://www.sony.com/electronics/marine/mex-m70bt

https://www.sony.com/electronics/mar...specifications

The difference is that the circuitry is better protected for use in a marine environment on a boat. It should therefore last longer. Mine is installed in the saloon. It comes with a little, again, not waterproof/resistant remote control. Or I can control it from my mobile phone, which does have an IP rating, using the Sony app.

My last, car, stereo did indeed last several years but, as this specifically marine set did not cost much, under £100, it seemed silly not to have something with all the functionality one could want yet might last still longer.

[mark0978]

Measure the current first. My radios draw almost 1A when off, which sucks because I have 2 of them. The Yellow wire is the one that needs to stay connected to power, that one draws almost nothing. I cannot fathom WHY a radio would need to draw nearly an amp while it is off unless they are trying to keep the amplifier circuits warm or the engineer was really lazy.

[Lake-Effect]

Originally Posted by mark0978

Measure the current first. My radios draw almost 1A when off, which sucks because I have 2 of them. The Yellow wire is the one that needs to stay connected to power, that one draws almost nothing. I cannot fathom WHY a radio would need to draw nearly an amp while it is off unless they are trying to keep the amplifier circuits warm or the engineer was really lazy.

If it's a car radio, there are often other functions that the car radio does when "off" but the car is "on" - eg clock, time display.

[capt jgw]

My stereo is wired through a breaker for the red power wire and the yellow wire is connected to an unswitched bus. I never use the radio's power button, I turn it on and off with the breaker. That way the memory stays alive and there's no parasitic drain when the radio is off. The radio takes maybe 5 seconds to boot up that way, I've never checked to see if it's quicker using the power button, and I don't really care.

[sv.antea]

Up until the time I connected my latest Kenwood receiver, I was always under the impression that the yellow wire was the high current wire and was to be always on, connected to the battery, thus avoiding voltage drop in the extra wiring and the iffy ignition switch. Soft voltage supplied to a high power audio amplifier reduces fidelity. When the red wire gets 12V, it is only a signal to turn the gadget on. I almost wired the Kewood wrong and now I wonder if remembered wrong or if there were such models back when I started installing radios in cars and boats. Either way, when the red wire was not powered, the yellow wire would carry only the minuscule current to keep the memory on.