Dell 1907FPt - 2 Secs to Black

[MEB]

Hello.

I have one that according to retiredcaps guide is a classic 2 Secs to Black. Depressing the power button turns on the backlights for 2 Secs, backlights go out, power button LED stays lit and flashlight test shows video is still on screen. I have just ordered all the caps on the power board and will install when I get them, but since it is operating this much, I wanted to see if I could get anywhere while waiting. Don't know alot but trying to follow the guide I did this much. On the connector from the power board to the main which has no labeling except P802, I get (calling Black Pin 1), in standby mode, 1-Black 5.2V, 2-Brown 5.2V, 3-Red 5.2V, 4-Orange 5.2V, 5-Yellow Gnd, 6-Green Gnd, 7-Blue Gnd. 8-Purple 0V, 9-Gray 0V, 10-Black 3.28V 11-White 0V. When Power is depressed, Backlights turn on and Pins 9, 10 and 11 read 3.26V, then backlights shut off and Pins 9, 10 and 11 remain at 3V until Power is pressed off at which Pins 9 and 11 return to 0V.

I had a 17" Dell and used one of its CCFLs to replace the 4 on this monitor, and if I didn't do anything wrong, got 2 Secs to Black with the spare replacing one at a time. I attempted to try to check the 2 inverter transformers, but don't think I know what I'm doing there without seeing inside one.

So once again I am at the crossroads of lack of knowledge and ready to learn more if someone wants to teach me. Would really appreciate the help.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Received most of the caps for the power board, so will change all I can and report back.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Replaced all the caps on the power board except the 5 that were backordered. Thay look good and the ESR checked good. Connected together and all is like before, 2 Secs to Black.

[Lumberjack777]

Re: Dell 1907FPt - 2 Secs to Black

You'll need to test the inverter transformers. Test resistance on the secondaries and see if they are within 3% of each other.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

I attempted to try to check the 2 inverter transformers, but don't think I know what I'm doing there without seeing inside one.

Thanks Lumberjack. Well I guess its time I found out how to test a transformer. Previously I tried using retiredcaps instructions, but at the time I was confused, because there were pads under the transformer that were not actually connected to the transformer which caused my misunderstanding. So I removed one of the two from the board (T102) and things became clearer. I included some photos which may help some guy like me someday. Now the primaries on T102 read .3 ohms and the secondaries read 465.2 ohms. Now knowing what goes where I tested T101 in circuit and got p = .3 and s = 472.5 which is within your 3% so I think I am good?

If I don't hear back shortly, I plan to make a lamp circuit tester using Bud's instructions as I am not real sure about the way I checked the lamp circuit earlier. If his lamp lights up, then I shall be waiting for further help. Thanks again.

[Lumberjack777]

Re: Dell 1907FPt - 2 Secs to Black

I'm sorry, I got sidetracked. Yes. That's within 3%. There are other tests like a ring tester for them. But for now, it doesn't appear to be the inverter transformers. Sounds like the lamp tester next step is a good idea. Good luck.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Hello,

Thanks for checking back. I have been wanting to do this for a while, so since I needed it now, I made the "Bud-Zapper". I enclosed a photo as I am pretty darn proud of it. All credits to the inventor. Hope he doesn't sue me! Note: The lamp base has no function, but I kept it cause I liked the chrome look.

Anyway, I replaced the lamps one at a time with the "Bud-Zapper" and as neat as it is, I still got 2 Secs to Black.

Oh, by the way, I received the rest of the caps and replaced them, so the Power Board has all new Panasonic capacitors except the big one.

Really could use some more direction as I am not sure what to do next.

Thanks.

[Lumberjack777]

Re: Dell 1907FPt - 2 Secs to Black

Bud-Zapper. NICE! hahahaha (I'm sure Bud would be proud. I hope he stops by to help out)

Well darn it anyways. I was hoping this would be an easy one. You've done everything right.

The next thing you need to check are the 5 components I circled in the inverter circuit. Looks like 3 transistors and 2 mosfets. Retiredcaps "2 seconds to black" guide shows how to check those. At this point, its probably one of those fets.

[budm]

Re: Dell 1907FPt - 2 Secs to Black

Nice! So you made two at least to test as a pair since there is possibility of having two bad lamps?
http://s807.photobucket.com/user/bud...ml?sort=3&o=11
http://s807.photobucket.com/user/bud...ml?sort=3&o=17

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Only made one, but I see what you are saying. Hadn't thought of that. Good thing I got a 4 pack. I will make 3 more, test the things Lumberjack suggested and be back to report. Thanks for your help.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Nice! So you made two at least to test as a pair since there is possibility of having two bad lamps?

OK, I read this statement a hundred times, but I just couldn't see what you were trying to tell me. I had full intentions of making 4 test lamps cause that would remove all doubt. But I broke one which meant I could only have 3, and kept thinking back to “so you made two at least to test as a pair” so I convinced myself 2 would be enough. So armed with 2 test lamps I went back to it. Yesterday I thought I could just plug the test lamp in one socket at a time and if it lit up for more than 2 sec, problem solved. Bad lamp.

But then budm tosses a monkey wrench in the mix and said “so you made two at least to test as a pair”. After reading that and thinking about it for a second, it was obvious now. What if you had 2 bad lamps? So off I went and made another test lamp. It was perfectly obvious now. So now I used the 2 test lamps on each transformer and then switched both of them to the other transformer. What else could it be? So completely fooling myself again, I spent the rest of the day looking up datasheets and reading posts on how to test the components Lumberjack suggested I check now the lamps are obviously good.

But that statement, “Nice! So you made two at least to test as a pair since there is possibility of having two bad lamps?” kept hounding me especially when all Lumberjack's components checked out good to me. So I made a little sketch showing what if 2 lamps were bad. After looking and playing around on that drawing, the message budm was trying to relay (and I was too stupid to realize it) hit me like a ton of bricks. You have to have 4 test lamps to take the easy way out or, if you use your head you have to have,

“ two at least”

Oh my God, I am such an idiot. Now I see to pull this off I have to use at least 2 lamps in a pair and they must be connected in 6 unique combinations to tell anything of value. But what are the chances of that actually happening? But I had to try. And lo and behold on the sixth position of the pair of lamps, both “Bud-Zapper” and “Bud-Zapper 2” lit up and stayed lit up and are still lit up! Man my head hurts.

So in summation, I believe I have 2 inverter transformers which power 4 lamps, 2 on each transformer. I also believe I have one bad lamp on the first transformer and one bad lamp on the second transformer, which causes 2 Secs to Black. So when the 2 bad lamps are disconnected and replaced by the 2 test lamps the monitor stays lit.

Please confirm if that makes sense, as it should already be obvious I have quite an imagination. If I don't hear back, I have no choice but to dive into the screen.

Many thanks to budm and Lumberjack777!!!! for getting me this far.

[Lumberjack777]

Re: Dell 1907FPt - 2 Secs to Black

When you have the good test lamps plugged into the connectors with the bad lamps, it will stay lit. YES, you got it. That was a good idea budm had to test that. What's RARE is to have one bad one on the top and one on the bottom, at the same time. I wonder if the monitor was dropped or bumped? I have never had one on the top, and one on the bottom, go bad at the same time. ANYWAYS........ if you are absolutely sure; then you have 2 options (depending on how much $$ you want to spend, and how much effort you want to try)

Option 1 - (the easy way) Is to get 2 extra ccfl bulbs and plug them into the bad bulb connectors. Then tape the ccfls using like duct tape to the back of the lcd panel. The monitor will run off 2 bulbs and may or may not be bright enough for you. In my case it's always been bright enough. You could check the front of the screen with those 2 "Bud Zappers" plugged in and see if the screen is bright enough with just 2 ccfl's.

Option 2 - Disassembly of the lcd panel. This is a fairly long and delicate operation. Usually takes me a couple hours. And you'll need to buy some replacement ccfls. Keep track of the placement of the diffusion plastic sheets. Pull the ccfl holders out from the top and bottom. Pull off the silicone end caps. Solder in the new ccfl's. And put it all back together.

Now you see why I normally just choose to add a ccfl to the back. Plug it in and tape it, and send it on it's way. Takes me about 2 minutes.

Your choice

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Thanks Lumberjack. Your suggestions are welcomed. Lord knows I am not made of money and the cost of new lamps is surely more than this monitor is worth, but I am on a mission. I learn so much from you guys that I can't put a dollar amount on the value of the education I am receiving, not to mention the enjoyment. I imagine I will keep going.

I have only seen the inside of one Samsung TV LCD screen with 14 long, narrow lamps so I am not following you exactly on the "top" and the "bottom" comments you made about this screen. If you care to elaborate I would appreciate your insight. If not, I guess I will probably find out.

Either way, thanks again and I will let you know what happens!

[Lumberjack777]

Re: Dell 1907FPt - 2 Secs to Black

I figured you for an "on a mission" type of guy. I was the same way when I started out. I'd take things apart to the very last screw.

These monitors have 2 bulbs on top, and 2 bulbs on bottom. They light up the inside of a thick piece of plexiglass.

So then, what you'll need to do is..... Get down to the lcd panel itself. Then take the little screws out of the controller board. It will be flimsy and has colored tape circuitry that goes to the panel. Always be careful of the colored tape with the little board attached. Never pry on, or damage that tape carrier package. Now you'll want to pry off the outer metal frame. I think the lcd screen comes out next. Then pry off the outer plastic frame after that. There may be some tiny screws holding it in place, and wires from the ccfl's. You'll eventually get to thin plastic sheets inside. These need to be reinstalled in the same order. That's important. Then comes the thick plexiglass. The bulbs will be held in a sort of metal holder that runs the entire length of the monitor, on the top and bottom of the plexiglass. This usually just slides off exposing the 2 bulbs on each side. You'll see the ccfl's then. Maybe even see cracks or breaks. Then you slide off the end white silicone end caps from the bulbs. You'll probably want to get 4 bulbs, since you are already replacing the top and the bottom ccfl's.

I refer you here now because it explains the ccfl soldering process.
http://www.ccflwarehouse.com/lasotu.html

Check out the tutorials there. Like measuring the ccfl's for replacement. You might be able to find replacement ccfl's cheaper on eBay or somewhere else.

Assembly is just the reverse of course. Those lamps are very fragile and also contain mercury. Once I was replacing some ccfl's and wasn't paying attention and simply set my needlenose pliers down on the bench. Right on top of a fresh new ccfl. That's all it took to break that thin bulb into smithereens.

Somebody out here once said that ccfl replacement is patience, focus, and more patience. And I'd have to agree.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Thank you very much for your excellent explanation. You are very kind and knowledgeable. I will do your suggested reading and proceed.

But ..., although this is my highest priority, my wife has informed me that our gas furnace failed to start on its annual maiden voyage, and although my mind says "monitor", she says "furnace" and everyone knows the outcome of that. So I may disappear for a few days, but I promise to report back.

Please check back if you can.

[budm]

Re: Dell 1907FPt - 2 Secs to Black

This is how I test the inverter using a pair of test lamps and how I take the panel apart.
https://www.badcaps.net/forum/showpo...&postcount=119

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

thanks budm, still in the furnace, but I might get to your method in a few days.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Well I am back. Waiting for furnace part and I couldn't stay away from the problem at hand. I feel kinda sick now. What a nervous ordeal. I started out planning on taking very detailed photos and got so involved I put the camera down and hope I have a good memory with all those diffuser screens. Everything went very slow and very precise until I got down to removing the lamps and wires from their little bracket. The top wasn't too bad and is still 100% intact, but the bottom set was pretty crunchy. I tried so hard to work those boots off but they were so brittle I failed miserably. I need some help (mental included) but I am more determined than ever to get this thing back together and working again. I believe if I had new wire, lamps and boots, I could restore the lamp assemblies to working order, but I have no idea about obtaining those parts. If the tiny inverter connectors and wire are available, I am pretty sure I can get new lamps. Please help if you will. I don't want to have to research wire and connector specs if I can obtain the stuff easily. I know I'm nuts but with or without your expertise, I have to do this. I'm taking off work tomorrow to hopefully finish the furnace, and I really need to step away from this for a day or two. If you can help me, it won't mean you are nuts just because I am. I would sincerely appreciate it. Thanks for all the help so far and I will keep you posted.

[Lumberjack777]

Re: Dell 1907FPt - 2 Secs to Black

The most cost effective way now is to salvage the connectors to the boards. Use any wire that you can find that is similar. (or the original) and buy bare ccfl lamps from China or somewhere. You'll need to measure or locate the ccfl diameter, and the length.
If you were to buy the complete assembly with lamp, end caps, wire, and connector; it'd run you about $15 per ccfl.

[MEB]

Re: Dell 1907FPt - 2 Secs to Black

Hello, sorry I took so long. I looked around and found several chinese lamps on ebay, but they were all for quantities of 50 to 100. The price was still good but I didn't know what I would do with all of those and I was not sure what I was getting. Are those lots any good?

Being my first lamp replacement on a monitor, I went ahead and ordered 2 sets with wires from ccfl warehouse. I was able to follow the instructions and the new boots were nice and soft and I was able to move things around enough to install them in the reflector things. I am still shaking though. I learned that next time I need to do a better job of identifying the way I keep tabs on those screens/diffusers or whatever they are called. There were some cutouts to prevent left and right switching, but if I didn't get something in upside down I would be amazed. Anyway, she lights up and stays lit and I had a great (but nerve-wrecking) learning experience. Thanks so much to Lumberjack and budm.