TV install

[travis1]

HI, we are installing an entertainment system on our 1985 37' Passport sailboat. My question concerns the TV. We are trying to avoid using the inverter as much as possible. I found a 20'' LCD flatscreen Tv that is labled input: 12V DC on the TV. It came with a standard home AC plug and an AC to DC converter. The converter is labeled input: 110-120V AC, output: 12V DC. My question: is there any reason we could not/should not cut the wire just short of the converter box (on the DC out side), splice the wire (it is triplex, 300V DC) and hardwire it directly to the 20 AMP bus bar that the car stereo reciever/ DVD player is connected to? According to my very basic calculations the total numbers for the circuit would be 9.8 amps and 117 watts based on the numbers labeled on the individual components. The wire run would be about 3.5 feet one way. The circuit (TV, DVD, Reciever/CD) would be on it's own breaker. The guy at the car audio shop seemed to think this was a good idea as the TV would be grounded with the DVD and would reduce interference that you may get if the TV were on the inverter and the DVD were 12v, but i did'nt really trust that guy. Thanks for your thoughts,
Travis

[Tim B]

Inverters are rarely ever good, and 240 volts around water is often questionable. The short answer is yes, taking 12 volts off the boat supply will work no problems.

However, There is more trouble to come. Inverters (well, the cheap ones) usually use a square-wave, not a sine-wave, so if you're trying to get good sound/video quality you may be dissapointed. There are some pure sine wave invertors around, but they're not cheap.

Thankfully, an audio power-amp (which wouldn't like dirty mains) isn't a problem because of all the 12 volt in-car entertainment kit. I am using a NIKKAI EAPA 250 (2chan 100W/chan (max) ) which you can pick up for about £50. It's actually quite good, I think the cheap computer sound card is the culprit more than the amp.

There is a problem, though, that DVD players tend not to be 12 volt, and they [240 volt] certainly won't like the power from an invertor.

If it was me, I think I'd consider installing a cheap computer, and running the entertainment system off that. Have a look on www.ebuyer.com The only problem there is that you will need to build a power-supply to run the PC. It might be worth considering as bundle deals on modern PCs come pretty cheap these days. If you want to work with Linux on it (by far the most flexible solution) you will need a decent graphics card. WIN XP is not as piccy on graphics, but the sound is lower quality on any given hard-ware. Advantageously, an on-board PC will give you oppertunities to upgrade the whole system later to include internet/office software and, most importantly, Data Aquisition and display software.

If you want to know more about on-board systems, e-mail me at Tim@MarineDesign.tk as it is something I'm seriously considering for a new boat.

Basically, the answer is yes it will work fine, just be careful of 12volt DVD with only Digital COAX outputs, you will need a DAC to use them.

Tim B.

[longliner45]

we have inverters on our trucks .I work for a power co. we use them in emergancys,,ie life support system in a home when the power is out,also use them to run a piece of equipt, called (the thumper) all is well as long as the motors are running ,but sometimes we forget ,and leave them on and they will kill a battery fairly quick.