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HDTV modification and repair help needed...

IjabaFilms

New Member
Hi,

I'm a filmmaker working on a project where I'm trying to build my own production monitor large enough and with a high enough resolution for focus pulling. Sure they sell production monitors but they are a gazillion dollars for the guerrilla filmmaker such as myself. :)

Anyway, I went on eBay and bought a 15" HDTV that just has a bad inverter. The TV only cost about $30 total. :) So I get it and turn it on and the TV comes on and stays on for about 5 minutes then the screen gets black. I shine a light on it and I can see the TV is still on and working. So yes, we have a problem with supplying power to the CCFLs.

With this particular TV (I bought some others but they are easy fixes), I opened it up and saw that it has a PSU board that connects to the mainboard (the other TVs I bought had a DC jack right on the main board so all one has to do is replace the inverter which is a separate unit). This TV has the inverter right on the PSU.

From what I understand of this situation, the portion of the PSU supplying power to the TV is fine but the area designated to run the CCFLs has a problem. I'm thinking of two things here...

1st. I actually would love to do away with the PSU and find a way to put a DC jack on the main board instead and use an AC adapter or 12v battery pack instead. This would be ideal because I have a 12v battery pack and would love to not have to worry if there is an available wall jack in a shooting location.

Then I can just use the 2 light inverter I already bought to fix the backlight problem.

But if doing away with the PSU is not possible, How can I remedy the inverter issue when the inverter is on the board that powers the TV?

The PSU connects to the mainboard via a 14 pin double row right angle header and the mainboard has the female header connector.

Here are photos: (image descriptions are at the bottom of the images)
Three West| Phelp

The yellow board is the PSU.

Any help would be appreciated. I don't know a whole lot about electronics but I have been having a good time learning and I want to know how this all works. From what I was reading, the mainboard accepts 12volts and the PSU converts what comes out of the wall into 12volts??? Am I understanding the point of the PSU correctly?

Thanks!
 

Menticol

Active Member
Don't insult yourself calling you "guerrilla", we have enough problems thanks to these ****** ***** ****** terrorists.

Reading what you said, I understood your TV uses a separate black box, that is plugged in the back of the TV, and converts the 120 VAC from the wall into 12VDC

Your broken PSU takes these 12VDC and elevate them to hundreds of volts, enough to light up the white fluorescent tubes that illuminate the screen (like the white square lights where the doctors put the radiography sheets)

First, make sure that your new inverter can light up adecuately the screen, even if connected with an external 12V wall mart

If that suceeds, why you don't just attach the new inverter in the TV's case, and plug it to the TV's DC in?
 

IjabaFilms

New Member
Reading what you said, I understood your TV uses a separate black box, that is plugged in the back of the TV, and converts the 120 VAC from the wall into 12VDC

Your broken PSU takes these 12VDC and elevate them to hundreds of volts, enough to light up the white fluorescent tubes that illuminate the screen (like the white square lights where the doctors put the radiography sheets)

First, make sure that your new inverter can light up adecuately the screen, even if connected with an external 12V wall mart

If that suceeds, why you don't just attach the new inverter in the TV's case, and plug it to the TV's DC in?
Thanks for your reply. There is no black box actually, its just a PSU that is housed inside the TV with the mainboard. The inverter is actually on the PSU. The Inverter is also bad. I get no readings on my multimeter from the transformer for the inverter (I'm not even sure what kind of readings I should get but the MM readout doesn't change no matter what setting its on when I touch the leads of the transformer).

Also the TV doesn't have a DC jack but I'd like it to. And I could plug it in but I'd rather run it off a battery because I may be shooting in locations with no power.

From what I understand, the PSU turns wall current into 12V current to run the TV. If the TV needs 12vs to run, then I should be able to power it with a 12v battery if I can get the a DC jack where it can work with the mainboard AND a way to power a separate inverter (which I've already bought).

Also there is a thing called a Pico PSU that the manufacturers claim I can use for this TV. I'm going to look more into that. It's a tiny PSU starting with 90W all the way to 200W and is no bigger than a quarter. It also doesn't need to be plugged into a motherboard to power electronic devices.
 
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