Curtis LCDVD244A

[landyboy]

Got another freebie and I think i have diagnosed the basic problem. The power board appears to test good. Symptoms are Power light comes on red and will go green when unit powers up but there is no picture. After checking the back light inverter I found the feed is as follows:
VCC 12.10
VCC 12.10
EA 4.767
Adj 0
Ground 0 ohms
Ground 0 Ohms
There is no voltage at the inverter plugs feeding the back lights. I checked F1 and it is 0 ohms.

I think I have a bad inverter board thoughts?

[landyboy]

Re: Curtis LCDVD244A

Do these voltages look correct? What is the "ADJ" a reference to and does it look correct? Thanks

[budm]

Re: Curtis LCDVD244A

ADJ (Adjust)= Backlights brightness control. 0V = Min brightness
EA (Enable) = BL_ON = Backlights on control .

[landyboy]

Re: Curtis LCDVD244A

Would the 0v indicate a problem?

[martyparish]

Re: Curtis LCDVD244A

Is there a voltage at F1 when set is on?

[landyboy]

Re: Curtis LCDVD244A

yes 12.10vdc

[landyboy]

Re: Curtis LCDVD244A

I assume you mean the F1 on the inverter

[budm]

Re: Curtis LCDVD244A

If you get 12v at both ends of the fuse, then try this, disconnect the ADJ line from the connector, then use 1K~2K resistor to feed 5V into the ADJ pin of the inverter board and see if you will get backlights.

[landyboy]

Re: Curtis LCDVD244A

Ok tried that but no change. I do now notice when I power on it will flash white for a split second. Also if I shine a flashlight on the screen I see images and the menu when I press the menu button.

[Clydeuk]

Re: Curtis LCDVD244A

Try the resistor trick mentioned (remove the adj wire out of the connector first). If it doesn't fire up the backlights I'd say inverter has failed. Don't try to measure the outputs, they are high voltage high frequency (around 1KV ish, more to start the lamps).

[landyboy]

Re: Curtis LCDVD244A

Did that with no change. Leaning towards a bad inverter...

[Clydeuk]

Re: Curtis LCDVD244A

You can get a 4 lamp universal inverter cheap, I keep one for testing, most are virtually the same, even ones that are built in to the power supply can be isolated and one of the cheapo's fitted, the trickiest part is usually mounting the board inside somewhere.

[Clydeuk]

Re: Curtis LCDVD244A

I've also pulled a couple of simple single lamp inverters out of old scanners, not used them but could be useful to test individual lamps in an assembly. Does the backlights even light for a second before going off? That could suggest a bad CCFL tube or connection (I've had both on these cheap sets)

[landyboy]

Re: Curtis LCDVD244A

The back lights seem to flash for a split second. I

[vinceroger69]

Re: Curtis LCDVD244A

https://www.badcaps.net/forum/showth...er+testing+cfl
http://www.ebay.com/itm/1pc-4-Lamp-B...item2ec1122f4b
both of these help me a lot in this situation to fault find.

[Clydeuk]

Re: Curtis LCDVD244A

Common faults on these cheap sets, capacitor failure, transformer failure, bad tube (broken), arcing connection between tube and metal shield (probably poor heatshrinking). These are some I've had anyway. If you can get a tube (from old screen, monitor, laptop etc) you can use to test each output. The inverter will need all 4 connected to stay running so do one at a time. If it's a tube fault you will know pretty quickly as with the bad one substituted it will fire up and stay on, with your loose tube lit as well. Then you have the nice part of taking the lcd assembly apart and trying to source a tube cheap enough to make repair worthwhile.

[landyboy]

Re: Curtis LCDVD244A

Ok I may order an inverter or just put this on on the back-burner for now.

[Clydeuk]

Re: Curtis LCDVD244A

That will be a quick fix if it has failed, you may have to rearrange the input connector to match, though I've been lucky and one I got had the same pinouts. It's probably your best way at the moment unless you can get a working tube to test each output, since any failure in a lamp or connection to it will shut the drive off, pretty quickly.

[landyboy]

Re: Curtis LCDVD244A

Ok got the cheap inverter and replaced it now set works fine. The pins on the generic board were exactly the same as the original board.

[Chickadee]

Re: Curtis LCDVD244A

Hi Conduit just wanted to know where I can get a inverter board from
I have the same model with the same problem.