dell 2007 WFPb monitor ,no lights

[selldoor]

Re: dell 2007 WFPb monitor ,no lights

In answer to your query the backlight is the lighting that is behind the screen in you case it will be a number of ccfl tubes ( cold cathode fluorescent) put simply these are lit by the inverters (3 transformers) on the inverter board, and are usually on ALL the time the set is on with a PC connected and on (not in sleep or standby) and producing a picture.

When the screen is dark it can be due to either the backlight not being lit OR the computer or monitor mainboard is producing a Black image which does not allow light through from the backlight.

However in the latter case it is usual to be able to see from the back of the monitor
some signs of light and the screen will be a slightly different black colour to when it is
off ( hope that makes sense)

[selldoor]

Re: dell 2007 WFPb monitor ,no lights

on the monitor i am using now ,i see a strong blue screen when i turn it on with the cpu disconnected , and a small square sign that says "RGV,VIDEO LOSS"and it stays on as long as the monitor stays turned on.is this what the backlight on the dell 2007 monitor should look like?
on the dell 2007 i think i remember seeing a white screen with a small blue square that said "NO ANALOG INPUT",and i dont remember if it disapeared after a while.

Monitors vary in what they do - Re the 2007 you are saying that is what you think it did when it was working? not now?

When troubleshooting if possible you should have a PC connected with a know image up and running ( Sleep and power saving should be switched off.

Many monitors and I think the 2007 will switch into standby mode if there is no signal after around 10 seconds (But time varies) In that time they will display No Signal or something to that effect.

let me try your suggestions ,do i have to screw all the boards back into the frame of the monitor? ,or i can try to somehow do it with the boards out, the way they are now?
everybody's suggestions are welcome and appreciated by me ,it gives me an opportunity to learn something else at my old age,and i thank everybody and ask you to keep posting them.

Hmm that is a difficult one to answer When there are so many boards its a major task to keep putting them in and taking them out of the frame BUT
the boards interact and they all need to be grounded - If you look at the boards you should see metal tags or raised solder like a "sun" around some of the screw holes where they attach to the frame and that is how they ground
(we have had occasions where after many days of troubleshooting the OP
(original poster) gave up and put the set back together gave it one last go befor chucking it and it worked !!! )

If you leave the boards out can you connect them ALL up and plug in the lights.- Sometimes the boards have to be turned over and layers of cardboard put between. Do not work on a metal surface!! or on an antistatic bag.

I think for a first test put it all back together in the frame - you only need use screws to hold it in place and only need really tighten one earth screw on each board.

That test that Davi P suggested is a good next one. When its all together
unplug the lvds cable (Its the bottom socket in your last picture in post3) ( that stops the image signal going to the screen so should let us know for certain if the back light is on or not)

After that some test may need the boards removing again.

I forgot to say in the chat - it is helpful if you are going to be missing for a day or even half a day in view of the time differences to just say so then we dont have to keep checking the thread for reply. If you dont get a reply to something within 24 hours its worth giving a friendly nudge " anyone any ideas" is much better than "Bump"

[Davi.p]

Re: dell 2007 WFPb monitor ,no lights

"so who is troubleshooting for a bad backlight?" Ok i dont had read well, i saw a desoldered transformer i tought it had been suggested, (to Ortiz) anyway arrived to the 20th post we still dont have done the "pointed lamp" test (read the past msg if you don't remember)..

"is this what the backlight on the dell 2007 monitor should look like?" No, when you have an almost black screen can be noticeable a surrounding light when backlight is on so the real color is not really full black but a very dark grey.

"do i have to screw all the boards back " yes it's not an huge job it's enough to screw 2 screws per board..

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

thank you selldoor and all that replied,
here its something i tried,since is the first time i take a monitor apart,i venture into finding out what a backlight is and how it looks like.mind you i may have done a nono because i probably wont be able to put it back together,but i kept the parts in the order i took them out,i just will reverse that process and hopefully will turn out looking and working the same.
any way here is what i found: there are 6 skinny flourescent lamps(look alike) 3 on top of the metal assy and other 3 on the bottom of the same ,assy from the back of the screen unit.
3 of them look darkened on both edges and the other 3 on one edge only.
i dont know if this can be a problem ,but somebody said that bad lamps cause this dark screen problem.
i am enclosing pictures of them,a did not get a really good picture of them because the metal enclosure kept shining and reflecting in the camara,i tried with a flash,out in sun,put some dark sheets on the metal and this is the best i could do.
i am retired in mexico and i forgot the difference in time zone in other parts of the world,its 11 pm and i have been trouble getting my modem to work properly,it has been going on for a week or so,just today i have been trying to connect since 6 pm and i am just now connected.i dont know what time its now in UK but if i wake you up ,i am sorry,i dont mean to be rude.
thanks.
i see the pictures never got there let me try it again.

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

good morning,if you read the post to selldoor ,i post 3 pictures of the lamps on the screen assembly that i ventured into taking apart to see what they look like and where they are.
they look dark on the ends,but i dont know if this is bad enought to cause a problem.i did post the pictures but because i am having trouble with my modem for about a week,sometimes i can not connect and when it does it takes a long long time to send,i have a very weak signal.i am going to post the pictures again and see if they show this time.i will have to try to post those pictures tomorrow,the page has been uploading those pictures for the last 15 minutes,i lost connection once and i tried again,same results.
oh,i see 2 of the pictures got posted

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

new pictures of lamps

[Davi.p]

Re: dell 2007 WFPb monitor ,no lights

Yes i think your problem is the lamps, but 26 posts and you have still not done the "pointed lamp" test, that is the one that says 100% if the backlight is faulty. Oddly the lamps don't look so bad to let the screen never visible in the first seconds, anyway if i propose you to disable the protection for test or trim it to let you use the same lamps further we don't exit more so i think you have to do the "pointed lamp" and eventually change lamps and hope. changing lamps may involve to solder new ones to the old cables and is not so an easy job..

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

thank you davi,
i am ready to do the pointed lamp test ,i havent really done many voltage readings,i want to know the important voltages on the different test points on the boards.so lets start with that test.

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

any suggestions as to how to check the inverter to find out for sure if its bad anybody?

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

where does the 12 volts supply originate?
i am taking readings and there is suppose to be 12 volts across c50 on the usb/sound pcb and i dont see a thing there.
please help

[Davi.p]

Re: dell 2007 WFPb monitor ,no lights

Hi Ortiz, i don't know if you want mainly repair your monitor or learn something of it, in the second case i suggest you read well other threads, monitors are similar, if is the first i tell you that if with the pointed lamp test you see a dark image then your problem is for sure the lamps, if you think you are able to change smd resistor we can try to change protection and continue to use those old lamps for some months or more but if you have no money problems a change of the lamps is the surest way.

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

i can change smd components ,lets do it,i dont have any money to buy new lamps right now,i am using a monitor that i borrowed from my son,only until i fix mine ,so its my only choice,to fix it.i will like to do the pointed lamp test too,always interested in learning.
i have been looking at some pictures with voltages that budm posted and i can not find the 12 volts reading on c50 that he has on one of the pictures,do you happen to know where is generated? here is the place where that picture is
http://s807.photobucket.com/user/bud...?sort=3&page=1

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

i can change smd components ,lets do it,i dont have any money to buy new lamps right now,i am using a monitor that i borrowed from my son,only until i fix mine ,so its my only choice,to fix it.i will like to do the pointed lamp test too,always interested in learning.
i have been looking at some pictures with voltages that budm posted and i can not find the 12 volts reading on c50 that he has on one of the pictures,do you happen to know where is generated? here is the place where that picture is
http://s807.photobucket.com/user/bud...?sort=3&page=1

correction is c60,sorry

[Davi.p]

Re: dell 2007 WFPb monitor ,no lights

Im sorry but i dont have followed what Budm said, i only know that in my opinion the only test to do now is what i've said, after the possibilities are 2, furthers tests or new lamp/new protection value.

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

i think i like to do further tests,like you said before the lamps dont look so bad.

[Davi.p]

Re: dell 2007 WFPb monitor ,no lights

maybe i don't express myself well, but do you want or not make this pointed lamp test? For the protection modify unfortuantely schematic is not available so there is an only chance by studying from a better picture than budm one of the inverter board, more hires, both sides, it seems complicated but i can at least try.

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

lets do this pointed lamp test

[Davi.p]

Re: dell 2007 WFPb monitor ,no lights

i've seen other better photos but i cannot follow traces, maybe it is multilayer..

[aortiz]

Re: dell 2007 WFPb monitor ,no lights

how do you do the pointed lamp test?

[budm]

Re: dell 2007 WFPb monitor ,no lights

So right now with the lamp assemblies removed from the panel. I would plug the lamp sockets into the inverter board and have all the boards connected with running PC, then turn on the monitor, do you see the lamps flash on at all? and do you get 19V at both ends of the fuse on the inverter board. Also what DC voltage do you get at the INVR_ON (BL_ON) pin of the inverter board?
By the way, do not worry about 12V voltage yet, it is not needed, it is for the DC output jack to feed the Dell powered Sound bar for sound only.