12v tv only getting sound on 12v

[jerryz]

I have a Sharp 32'' 12v model TV which works perfectly on 240v but when on my vans 12v it only gives sound ,, seems not enough ooomf from 12v for screen to light up although it works fine when on my mates boat 12v system ???????????

 

[Richard n Ann]

Measure the supply voltage at the TV when it's switched on.. See if it drops.

 

[Lenny HB]

As Richard said measure the volts at the TV, probably due to undersize wiring.

 

[jerryz]

volts at tv pcb 12.85v

 

[Richard n Ann]

Do you have any 12v LED lights on when you lose the picture? Some cause interference.

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[Terry]

Years ago I used to use loss of picture as early warning of low power in batteries
Try a direct feed from a LB that you know has full charge this also works to eliminate low power to boiler

 

[Wh05apk]

We have a similar issue when using a firestick if the hdmi cable is not seated fully.

 

[WillH]

volts at tv pcb 12.85v

Is that the loaded voltage or no-load?

 

[jerryz]

Is that the loaded voltage or no-load?

Loaded with tv on , have sound but no picture ,,seems the tv wants more power for the screen to come on the cable is 1,5mm

 

[headlight]

Loaded with tv on , have sound but no picture ,,seems the tv wants more power for the screen to come on the cable is 1,5mm

12.85v should be plenty if that's what the TV is getting.

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[treblid]

Are you using the TVs internal tuner or an external device on HDMI?

If its on tuner, try a different source via HDMI that does not need DVB TV signal. This may help to eliminate interference knocking out the Freeview signal.

 

[jerryz]

Im watching on 240v mains its fine but when switched to 12v it only works on sound there does not seem to be enough power for screen its not the tuner ??

 

[Richard n Ann]

Im watching on 240v mains its fine but when switched to 12v it only works on sound there does not seem to be enough power for screen its not the tuner ??

I would run a temporary new 12v power cable straight from the battery and see if it will power the screen up from that.

 

[treblid]

volts at tv pcb 12.85v

So, are you saying, you have the TV back cover off and are measuring 12.85V on the printed circuit board at the 12V input?

 

[Jimbohorlicks]

You may be ok voltage wise but do you have enough amps, what are you plugging into?

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[treblid]

You may be ok voltage wise but do you have enough amps, what are you plugging into?

If the TV feed did not have enough current capability, the voltage would reduce.

 

[Richard n Ann]

If the TV feed did not have enough current capability, the voltage would reduce.

It might just reduce momentarily, then give up trying and the voltage recovers

 

[treblid]

Im watching on 240v mains its fine but when switched to 12v it only works on sound there does not seem to be enough power for screen its not the tuner ??

Is the TV in the same physical location when you switch between mains and 12V?
If so, is there anything else you are switching on and off at the same time during this test?

 

[treblid]

It might just reduce momentarily, then give up trying and the voltage recovers

It's unusual for a modern TV to trip out just on picture. The power supplies are mostly common.

 

[jerryz]

Is the TV in the same physical location when you switch between mains and 12V?
If so, is there anything else you are switching on and off at the same time during this test?

yes same place ,, nothing else being switched my on conclusion is that the TV wants more volts for screen ????

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[treblid]

yes same place ,, nothing else being switched my on conclusion is that the TV wants more volts for screen ????

Doesn't make any sense if your 12.85V is accurate and is right up to the input to the actual TV.
Your TV could have a fault and it needs more than this to now work. Have you tried it with engine running so the leisure battery is charging and at 13.8V - 14.4V?

 

[headlight]

yes same place ,, nothing else being switched my on conclusion is that the TV wants more volts for screen ????

Does your TV have a sticker listing operating voltage or does it say in the manual ?
Failing that what is the make and model of the TV?

 

[jerryz]

Its a sharp Ageous 32'' model only 1 year old ,, works on my friends boat on his 12v feed and It also worked in a caravan of 12v feed , but in My MH it is not operating correctly on 12v

manual says operating voltage is 11 - 19v the mains comes in at 240 and is dropped to 14.9v when it goes to the main pcb

 

[ChrisL]

I presume when it's working on 240 volts it's using a transformer in the plug type power source, if so have a look at the label on the transformer and see what the output voltage is, if it says 12 volts you may have to many volts going in, I have a router that won't work directly off the leisure batteries I have to use a stabilised power source set at 12 volts.

Edit: the above post shows my post is not the issue.

 

[jerryz]

I presume when it's working on 240 volts it's using a transformer in the plug type power source, if so have a look at the label on the transformer and see what the output voltage is, if it says 12 volts you may have to many volts going in, I have a router that won't work directly off the leisure batteries I have to use a stabilised power source set at 12 volts.

Edit: the above post shows my post is not the issue.

The 240v transformer and power unit is inside TV

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[treblid]

works on my friends boat on his 12v feed and It also worked in a caravan of 12v feed ,

Same cables from 12V socket to the TV?

Where exactly did you measure the 12.85V when the TV was on but not working correctly?

 

[treblid]

Its a sharp Ageous 32'' model

Sharp Aquos is a generic term for the range. There should be a full model number.

manual says operating voltage is 11 - 19v the mains comes in at 240 and is dropped to 14.9v when it goes to the main pcb

From your description above, I assume you are just putting 12V on the connector that takes the output from the 240V mains power pack?

 

[Terry]

A 12v battery is a pretty stable source of power !
Just a suggestion try starting the engine then your tv- when engine is running the alternator will be shoving around 14 plus volts and that may be enough power If it does work then check your Leisure battery/wiring

 

[jerryz]

Sharp Aquos is a generic term for the range. There should be a full model number.


From your description above, I assume you are just putting 12V on the connector that takes the output from the 240V mains power pack?

No there is dedicated 12v input socket in back of TV with its own cigar style plug