LED there be light...but no picture.

[Sledge Fingerhammers]

The fuses finally got here, and I finished modding the 19M009 PSU board for the LED conversion of my Westinghouse L1951NW. Pic shows how I mounted the LED driver board. The black, white, and yellow wires go through holes drilled in the PCB and are soldered to the appropriate traces on the other side, Black to GND, yellow to Enable, white to ADJ.

What doesn't show very well is that I'm taking the 19.5 v from the air-mounted end of the glass fuse F200. The new fuse is bigger than the original, and I didn't figure the other side of the board needed the 20v anyway, so I only soldered the one end to the board, and put a glob of hot glue to hold it in place.

Voltages: 5v=5.04, 13.8v=14.02, 20v=19.54, V_Adj=2.34, Inv _Enable=2.91

Results, hooked to my laptop...not-all-that-bright white screen, no picture, and both the On and Standby LEDs lit up. Screen comes on when I plug the unit in, and the on/off switch has no effect. Removing the switch's ribbon cable from the VGA board has no effect.

So I've obviously made some dumb mistake. Any edumucated guesses?

I know the monitor had a picture before I started all this, because I could see it with a flashlight.

[budm]

Re: LED there be light...but no picture.

Sounds like you did not hook up the LVDS cable between the LCD panel and the logic board.
Backlights are just the light source so you can see image on the screen, if you have backlights but no images then it is either the logic board is not sending the signals to the LCD panel or there is problem with the T-CON board on the LCD panel.

[stj]

Re: LED there be light...but no picture.

maybe the 19v needed to go somewhere other than the lighting circuit.

that's a nice tidy install btw, they are obviously making the new invertor smaller than the ones i fitted.

[Sledge Fingerhammers]

Re: LED there be light...but no picture.

<i>maybe the 19v needed to go somewhere other than the lighting circuit.</i>

That's what I'm wondering. I mean, it's obviously the source for the high voltage section, but maybe feeding something else, too. I'm gonna try reinstalling F200 the right way, while still scabbing power for the LED board off the top. If that doesn't do it, maybe I'll go ahead and remove that controller chip you were talking about. Also gonna do a higher magnification search for shorted solder points underneath. It bothers me that the LEDs come on as soon as I plug it in, even with the switch unplugged.


<i>Sounds like you did not hook up the LVDS cable between the LCD panel and the logic board.</i>

First thing I looked at. Pulled and reinserted all 4 ends of 2 ribbons, plus the switch panel ribbon. Nada.

[budm]

Re: LED there be light...but no picture.

Check and see if you do have 5V feeding the SMD fuse on the T-CON board attached to LCD panel.

[Sledge Fingerhammers]

Re: LED there be light...but no picture.

Well, that was a flotz. Reinstalling the F200 so the bottom of the board got its 20v had no effect other than blowing the brand new 5v fuse F101.

I think I'll just depopulate the underside of the CCFL area like I did the top, and see what happens.

[budm]

Re: LED there be light...but no picture.

It is the same monitor as this one, right?
So are you still getting the Voltages of those pins?
https://www.badcaps.net/forum/showthread.php?t=44251

[stj]

Re: LED there be light...but no picture.

now wait - if connecting the 20v is blowing a 5v fuse something is very wrong.

try unplugging the cable from your new invertor and see if the fuse still blows - maybe there is a problem with the [on] or [dim] signal wiring/circuit.