DELL 2005FPWisplay goes black after 1 second

[triplefour]

got a Dell 2005FPW here that turns on for a second, displays everything properly, but then the backlight turns off.
there are lighted numbers 1-4 on the front of the monitor. it lights up number 1, then when the backlight goes out, it lights up number 2 for a second, then switches back to lighting up 1.

what are these numbers for? the different inputs?
im guessing thats what they are because there is a vga connector, a DVI connector, an SVIDEO connector and an old RCA connector as inputs for this thing.

i opened it up and could not see any signs of bulging or leaky capacitors (had another monitor that did the same thing and it was bad caps)

the power supply and inverter are on the same board.

i tried only plugging in 1 of the 4 connectors for the backlight and testing each one individually but its the same no matter if i have them all connected or just 1. if i disconnect all of them obviously i get no backlight at all.

i thought i would see it get dimmer if i had less of the connectors hooked up but it really seemd to have no change. why are there 4 connectors going from the inverter to the backlight if only 1 is necessary to achieve full brightness?

could the caps be bad even though they dont look it?
or what else could cause this problem?

[stj]

Re: DELL 2005FPWisplay goes black after 1 second

so what happens if you press the menu button?

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

there isnt a menu button...but there is some kind of picture in picture button...that does something...but then i cant see my desktop at all just a black screen with a little blue picture in picture window and then the backlight turns off after a second.
also i can press the source button on the button board to change source. the + and - buttons which should control brightness do not appear to do anything when i try to press them in that 1 second i get of visibility. they dont appear to do anything while the backlight is off either. after a while of no input the lights change to amber. if i then plug in to a VGA signal the tv will wake up and display the desktop for a second then back to black again.... not sure what any of this means... which is why im here asking u guys

[bammbammfran]

Re: DELL 2005FPWisplay goes black after 1 second

leds are input indicators

do the large plugs have 4 wires ? If they do then you have six bulbs in this screen
which means you may have to undo a few wires to try to check each bulb separately.
A picture of the large plug from both sides would help

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

not sure if these are the right pictures but ...

[bammbammfran]

Re: DELL 2005FPWisplay goes black after 1 second

This is a place to start to see if bulbs or transformers are possibly involved

As I figured you have six bulbs so when you are plugging in the large plug.
you are actually trying to light two bulbs and if one of those is bad, you wont see it since the other one will flash.
SO, if you want to do a flash-on test on each bulb, you need to plug one bulb in at a time
The 4 wire large plugs are wired different then some others. The two positive wires are the thicker ones and the thin ones are the returns
I am guessing that the blue goes with blue and brown with brown, so you would need to slide out the blues to check the browns and vice versa. You need to slightly lift the white tab of the connector at the pin for the pin to slide out (mark the colors on the plug before you remove them so you remember where they go in)

Flash test does not always mean that they are good, but this may tell if a transformer is not turning on or a bulb is totally shot
disconnect the wide ribbon or wiring harness that goes into the lcd panel rear from the vga board before testing the bulbs. this should make the screen white an will help you see if a bulb is only partly lighting or pink.
If one bulb does not light, you should try one that did light in that plug location (this will tell you if it is the bulb or transformers


If all the bulbs flash about the same brightness and all plugs create a flash then the problem might be elsewhere on the boards

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

ok i think i followed that. tested each lamp individually and they all turn on, but i found out that one of the inverter outputs doesnt work. no lamp plugged in will flash when plugged into this one, but then they do flash when plugged into a different one... so this one output from the inverter is not happening? wouldnt i just get a slightly dimmer screen though? i feel like ive been able to unplug lamps from the inverter and not even see any change in brightness of the backlight (in the other tv im working on this seems to be the case)

if one of those transformers is bad could it cause this problem im having? can i test the transformer itself? or can i replace them?

the picture here is the one output that makes no lamp turn on

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

oh and unplugging the LVDS cable did not make the screen white...still a black screen but i can tell when the backlight comes on or not

[philliesfan30m]

Re: DELL 2005FPWisplay goes black after 1 second

the 2nd 1 from the right inverter transformer looks to me like it got hot and is probably what is making it go into protect mode. you can check for resistance between the output legs and compare them to the other 5 i'm guessing that 2nd 1 from the right is bad just by looks and location as to what plug doesn't work with any lights. you can replace them if you can find 1. just google the number on the inverter transformer.

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

i realized i have 3 of these exact monitors. one of them has a problem with the LCD where about 2 inches of the screen on the right side is just plain white (blocks your view of some things but still kinda usable if u arent the OCD type)

so i decided to swap screens n see what was going on.
i swapped the slightly broken but mostly good panel in, and it turns on just fine and does just what the other one did.. white line on the side but otherwise fine.

so it seems that while one of my inverter transformers may be out on that board, i dont think it actually matters.

swapping the "guts" from one to the other and the panels back and forth confirm that both of the monitors guts are fine, but the panels are whats going wrong.

what would cause a panel to start up and then black out?

and what would cause a panel to have a bar of white space going down the right side?

i hope i explained things in a non confusing manner, but basically i double swap tested everything and both panels behave the same way (respective to themselves not to each other) no matter what guts theyre using.

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

the third monitor i have has a cracked LCD screen but seems like the guts are all fine

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

can i take apart LCD screens and swap parts? ive started taking apart the cracked one and theres some pretty cool stuff in here!

[stj]

Re: DELL 2005FPWisplay goes black after 1 second

blackout is probably bad tube(s)

the bar is the glass display, the board on the back of it, or the flat cable linking them.

take the tubes from the bar one, put them in the blackout one - you should have a good unit.

you probably found that there is a great sheet of acrylic behind the glass you can use for something else too - i use them to make shelves by putting them on tv-stand frames.

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

acrylic? do u mean the thick piece of plexi glass? theres a 1 inch thick plexiglass with kind of a honeycomb pattern on it... and theres like 3 or 4 sheets of some crazy thin plastic...

what are the tubes exactly? is that the TCON board attatched to a large mirror glass?

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

i think i need help understanding what u mean when u say take the tubes from the one that shows the bar and put them in the one that blacks out...

what are the tubes exactly and how would i remove them? they seem hopelessly attached to the mirror glass...

[stj]

Re: DELL 2005FPWisplay goes black after 1 second

tubes = flourescent cold-cathode tubes.
the backlights.
post a foto

[bammbammfran]

Re: DELL 2005FPWisplay goes black after 1 second

you probably went too far taking the cracked screen apart if it stayed lit
If it did stay lit, you should have just swapped the top glass piece from the first one to this one.
Easier than messing with films.

tubes are the six bulbs that are at the very top and bottom of the screen inside a silverish metal channel

if you do have it completely apart, you can use the bulbs as test lights to check each board while the bulbs are out

[stj]

Re: DELL 2005FPWisplay goes black after 1 second

those metal tube holders often slide out from the end where the wires are once the outer metal frame is clear.

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

ok still kinda unclear because i guess i just am not familiar with what all these are called.. im uploading a picture now of the only "board" or electronic part inside the LCD. its a circuit board attatched by thin ribbon cables to a thin peice of glass which is mirror on one side and black on the other. please point out which things are the "tubes" and how i would change them. what is the "top glass peice" ? there was only this, and some films, and a thick peice of plexi glass all housed in a metal case with some plastic edges in it that i had to remove to get the plexi glass out...
what might i have broken by removing all these peices? i didnt break anything worse than it already was... the mirror glass has a nice big crack in it and i dont think it can be seperated from the board so what exactly is salvageable here? sorry for being a noob! it will only be this once, i promise

[triplefour]

Re: DELL 2005FPWisplay goes black after 1 second

forgot the pics.
also there are some "tabs" coming off the side...are those the tubes??