12v TV Wiring?

[CJ13]

We've bought a new Logic 22'' Digital TV/DVD. The power requirement is 12v and it comes with a mains adaptor. There are dire warnings in instructions about not using any power source, other than the mains adaptor.
We would probably only use the TV when on shore power, in which case the nominal 12v supply is actually about 13.6v.
Does anyone know how sensitive these type of TV's are and whether i would cause harm by wiring directly to the boats 12v supply?

Thanks,
John

 

[VicS]

We've bought a new Logic 22'' Digital TV/DVD. The power requirement is 12v and it comes with a mains adaptor. There are dire warnings in instructions about not using any power source, other than the mains adaptor.
We would probably only use the TV when on shore power, in which case the nominal 12v supply is actually about 13.6v.
Does anyone know how sensitive these type of TV's are and whether i would cause harm by wiring directly to the boats 12v supply?

Thanks,
John

If you are only going to use it when on shorepower why not use the mains adaptor?

 

[Playtime]

Does anyone know how sensitive these type of TV's are and whether i would cause harm by wiring directly to the boats 12v supply?

It is impossible to answer the question without a full spec of the TV. However, I can say that I have a 17" Matsui TV that runs on 12V input and comes supplied with a mains adapter.

I use it on the 12V boat supply all the time, even when connected to shore power (which initially can be delivering 14.5V). It has worked like this for several years without problem. Of course, this is no guarantee that yours will be equally tolerant.

If in doubt, do as VicS suggests and run it on the adapter. If not on shorepower, run the adapter from a 12V 150W inverter.

 

[SolentPhill]

We've bought a new Logic 22'' Digital TV/DVD. The power requirement is 12v and it comes with a mains adaptor. There are dire warnings in instructions about not using any power source, other than the mains adaptor.
We would probably only use the TV when on shore power, in which case the nominal 12v supply is actually about 13.6v.
Does anyone know how sensitive these type of TV's are and whether i would cause harm by wiring directly to the boats 12v supply?

Thanks,
John

You may find the tv is on an adapter which drops it to 12v ac if you plug in to battery you will be 12v dc.

Could be wrong so check output.

 

[Mrnotming]

Logic 22" tv

I have a Manhattan brand with a brick AC/DC power supply unit.Somewhere I have seen this discussed before, that is, if intending to run the set from the ship's 12v supply, spikes may occur in ship's supply even if connected to the shorepower 220/240VAC and being charged by a smart battery charger.

As VIC s remarks, you will probably just use the mains if in port, and the "brick" will allow for fluctuation, and your set will be ok.

In the other case a 12v/12v device will be needed to avoid spikes.I suggest that
www.maplinelectronics.co.uk may have such a unit designed to smooth out any spikes, which if not filtered out could damage your set irreparably.
In my case I have not yet calculated the power consumption of this 22"LCD set (DVD at side) so I am unsure if it will be useful for a nav display yet. Maybe just as well to keep to present integral laptop screen, but I might be able to blank out the laptop screen and just feed video to the TV.(better keep the plot going on paper too!)
Best of luck with the TV, we found it brilliant after our old 12" CRT became useless(Analogue switchoff)

 

[earlybird]

FWIIW, I powered a freeview box from my battery instead of the supplied mains adapter. It failed quite quickly. Can't be sure that was the cause, but it's a prime suspect.

 

[CJ13]

In answer to Vic i'd rather have the TV permanently wired rather than plugging in and having a trailing wire. It would be quite easy to wire it into the 12v system.

John

 

[Spyro]

Got one that I just cut the mains adapter off and wired into the 12v supply and it works fine, also used it with engine running so that should be a suppling around 14 volts

 

[elton]

The TV will have internal voltage regulation and will work on >12v, but it'll get hotter as the regulator has to drop the excess voltage.

 

[bobgarrett]

If worried, why not measure the voltage output of the mains adapter - but do it with and without the TV connected (the former could be a little tricky but still possible).
I would almost guarantee that the adaptors voltage with no load will be above 12v and quite possibly with load too.
That will at least show what the manufacturer's variations are.

 

[No Regrets]

I have run a 12v TV with the adaptor chopped off for years, no issues at all!

 

[Sneaky Pete]

I have run a 12v TV with the adaptor chopped off for years, no issues at all!

Agree, I used my 12v TV in my motorhome a couple of years ago, my mate uses his TV in his lorry adaptor chopped off no problems.

 

[jordanbasset]

Agree, I used my 12v TV in my motorhome a couple of years ago, my mate uses his TV in his lorry adaptor chopped off no problems.

Yes we have used ours like this for over 2 years now, no problems, so far...

 

[Bloater]

Quite simply what you need is an Amperor 12v LCD TFT Stabiliser. It gives a 12v stabilised output from an input of between 10v and 28v and can supply up to 90W. I've used these in the past and they are exceptional.

They use less power than an inverter as there is no conversion of voltages going on - in fact the Amperor doesn't even get warm like the supplied PSU would, so there is less wastage. The price has gone up over the years though and I think they are now nearly £50. You can buy direct or look for them on eBay.

I have no connection with the company, just a happy customer.

 

[Mrnotming]

12v tv supply

So No Regrets,

here is the link for the item kindly suggested by Bloater:

http://www.reuk.co.uk/Amperor-12-Volt-LCD-TFT-Stabiliser.htm

and it seems to cost Stg 30.

 

[theoldsalt]

All the web sites I have looked at for 12v TVs say they should be run via a voltage stabiliser if being used at battery charging voltage (eg 13.8v)

They say excess voltage can significantly shorten the life of components and invalidate the warrenty.

So yer pays yer money and takes yer chances.

 

[William_H]

If worried, why not measure the voltage output of the mains adapter - but do it with and without the TV connected (the former could be a little tricky but still possible).
I would almost guarantee that the adaptors voltage with no load will be above 12v and quite possibly with load too.
That will at least show what the manufacturer's variations are.

Power plug adapters (known as wall warts by some) come in 2 different designs. Old style had a transformer in it. These would provide a voltage that varied from about 16v no load to probably closer to 11v under full load. You can tell a transformer type from the weight. Quite heavy for its size.
A more modern style uses a switch mode power supply. Here 240VAC (or 120vAC) is rectified and switched at perhaps 1 megahertz into a high frequency transformer then rectified. The switching device has a feedback of voltage so automatically adjusting to precise voltage regardless of load. These type are light weigh and usually specified for 120 to 240vAC without switching.
Now it is most likely that the TV comes with a switch mode power supply. This means that the TV is designed to operate on precisely 12vDC and so does not need to have the regulators internally. It means that 14v from a battery on charge will be way too much. I would not risk it.
Hence the recommendation to use the 12v to 12v stabiliser. (which incidentally does have switching and transforming so has inefficiencies like an inverter.
If the OP is always running the TV with charger on so 12v supply is always 14v then I would suggest a poor mans voltage reduction would be 2 silicon diodes in series on the 12v line. These will drop the 12v supply by 1.4 volts (approx) mostly regardless of current drain. So your 14v input will become 12.4 volts which might be more palatable to the TV. Diodes need to be rated at more than 4 amps but voltagee will not matter. Get them from RS or similar. good luck olewill

 

[elton]

Now it is most likely that the TV comes with a switch mode power supply. This means that the TV is designed to operate on precisely 12vDC and so does not need to have the regulators internally. It means that 14v from a battery on charge will be way too much. I would not risk it.

William, all TVs have internal regulation. Much of the circuitry in a modern tv is digital, and requires stablised 5 or 3.3V supply. The tuner requires a stable voltage for the PLL. Plus, the manufacturers know that the supply voltage cannot be guaranteed, and a low input voltage would result in a lower, unstable supply voltage which could damage the set, so the circuitry is designed to operate on a voltage a lot lower than 12V, and regulation is performed internally.

 

[William_H]

William, all TVs have internal regulation. Much of the circuitry in a modern tv is digital, and requires stablised 5 or 3.3V supply. The tuner requires a stable voltage for the PLL. Plus, the manufacturers know that the supply voltage cannot be guaranteed, and a low input voltage would result in a lower, unstable supply voltage which could damage the set, so the circuitry is designed to operate on a voltage a lot lower than 12V, and regulation is performed internally.

Yes you probably are right but can you be sure that given the input voltage is going to be precisely 12v from a regulated source (the supplied power pack) that they have not relied on this in design. ie not provided a regulator for 12v lines or that the regulators for lower voltage can cope with 14v input.
That is the unknown in this discussion. The critical question. If the answer is no you have smoke.... olewill

 

[nigelmercier]

measure the voltage output of the mains adapter

Do you know what current it takes from the 12V?

Two ways you can go with this: take some measurements of the PSU open, and with a comparable load. Or skip this stage and bung the 12V feed through half a dozen diodes (check their current rating), remove them one at a time if it doesn't switch on.