Dell E153FPB Back Light problem

[jschiefer]

Re: Dell E153FPB Back Light problem

I am back, sorry i have been away for awhile. I replaced all four of the 5707's on my power board and its still not working. I am still having the problem with the monitor going on blinking white and then black. It does that a couple times and then stays black. With a flash light, i see nothing.

I turned toward the diode trouble shooting. I have the board unpowered and was using a diode check, then reversing the leads. On some of them (all but two) i got a reading with the probes in both directions. What are the chances of all of these being bad. Thanks again for the help.

[FredW]

Re: Dell E153FPB Back Light problem

Just to say thanks for the info,was given a Dell E153FPB with the indicator light flashing and got the c5707's off the interweb thingy,pulled the case apart as per your comments the inverter board was clean no burn marks but found that a couple of joints were very dry,dropped the transistors and replaced all 4 then reflowed all the joints areound the inverter,put the monitor back together and oh joy it worked been on test now for 48hours.

[freakytiki4u]

Re: Dell E153FPB Back Light problem

Have a couple of days off it then have think about it
Good Luck
Bob

I wont throw it away, just set it off to the side. lol, I found a place that I can buy a refurb inverter board for $40.00 and thats not a bad price but it doesnt compare to the rewards of learning to repair my own stuff.

[freakytiki4u]

Re: Dell E153FPB Back Light problem

What temparatures do you all use when soldering on these inverter boards? I think I may have used a lil too much. I use 800 degrees F and i get in and out as quickly as I can so I dont put too much heat to the board. I use a radio shack soldering station ( i know I know, LOL) and 840 degrees Farenheit is its max temp.

[Bobdee]

Re: Dell E153FPB Back Light problem

You are correct. I just pulled the C5707's out and checked them with my MM and 1 was bad again. I replaced all 4 just to be sure but now 1 of the legs on one of the C5707's refuses to take any solder. I cleaned the area and am using rosen core solder but it will not take solder. I think that spot has just be soldered too many times. Im going to scrap this monitor also. Thank you for your assistance Sir

Have a couple of days off it then have think about it
Good Luck
Bob

[freakytiki4u]

Re: Dell E153FPB Back Light problem

The Power LED Just blinked repeatedly.

[Bobdee]

Re: Dell E153FPB Back Light problem

The Flat Panel I fixed has stopped working again. Now it just blinks on and off. Any ideas anyone? I was so excited to have it working.

Hello freakytiki4u
What did you mean in the above old post, did LED blink on/off or the screens B/Lights

[freakytiki4u]

Re: Dell E153FPB Back Light problem

You are correct. I just pulled the C5707's out and checked them with my MM and 1 was bad again. I replaced all 4 just to be sure but now 1 of the legs on one of the C5707's refuses to take any solder. I cleaned the area and am using rosen core solder but it will not take solder. I think that spot has just be soldered too many times. Im going to scrap this monitor also. Thank you for your assistance Sir

[Bobdee]

Re: Dell E153FPB Back Light problem

The Dell E173FPB I repiared is at it again. When I plug it in I see the Dell Logo for just a split second and it goes dark. Using a flashlight I can see the Dell Logo is still there, just not lit up. I have replaced the Pico Fuse and all 4 of the C5707's and it worked for a few weeks. Now its back to doing the same thing. I have resoldered every connection that even looked funny. I paid particular attention to the spots reccomended on the forums. Any other idea's or things I can test? Thanking you in advance.
Pictures are attached

If you resoldered all 4 Inverter Transformers then it is possible that you have a failing CCFL
Its is probable that you now have a failed C5707 again due to the initial fault being missed

[freakytiki4u]

Re: Dell E153FPB Back Light problem

The Dell E173FPB I repiared is at it again. When I plug it in I see the Dell Logo for just a split second and it goes dark. Using a flashlight I can see the Dell Logo is still there, just not lit up. I have replaced the Pico Fuse and all 4 of the C5707's and it worked for a few weeks. Now its back to doing the same thing. I have resoldered every connection that even looked funny. I paid particular attention to the spots reccomended on the forums. Any other idea's or things I can test? Thanking you in advance.
Pictures are attached

[PlainBill]

Re: Dell E153FPB Back Light problem

Thank you PlainBill, I will upload pictures tomorrow. In the mean time I tested the transistors again and I'm getting continuity between the collector and emitter, which means they are bad right?

Define 'continuity'. If you mean 10 ohms or less, you are exactly right. This is a fairly common problem with these boards. Here's what you do:

Check for C-E shorts on all four transistors (circled in red). If only one of a pair is shorted, replace both. Check the FETs for shorts (circled in blue). Replace if shorted, natch. IMPORTANT: Resolder all terminals on the transformers, even if they look good.

The parts can be found on eBay. You can buy kits of all parts, or if all you need are just the transistors you can buy them.

PlainBill

[jschiefer]

Re: Dell E153FPB Back Light problem

Thank you PlainBill, I will upload pictures tomorrow. In the mean time I tested the transistors again and I'm getting continuity between the collector and emitter, which means they are bad right?

[PlainBill]

Re: Dell E153FPB Back Light problem

Yes they all were. Its a cheap meter so i thought they were find.

I also looked at my LCD with a flashlight to see if i can see the image after it flashes white and i cant see an image. What does this mean?

It means something isn't working; probably either the logic card or the panel.

Take a good quality picture of both the top and bottom of the power supply / inverter. Don't use someone else's picture this time. There are at least two different versions of this monitor. Attach it to your next post.

PlainBill

[jschiefer]

Re: Dell E153FPB Back Light problem

Different brands of meters give different results. Were the results the same for all transistors?

PlainBill

Yes they all were. Its a cheap meter so i thought they were find.

I also looked at my LCD with a flashlight to see if i can see the image after it flashes white and i cant see an image. What does this mean?

[PlainBill]

Re: Dell E153FPB Back Light problem

I tested mine and got about 426 is that too far off?

Different brands of meters give different results. Were the results the same for all transistors?

PlainBill

[jschiefer]

Re: Dell E153FPB Back Light problem

Testing out of circuit with MM set on Diode Check
Red probe on B and Black on C, Should read about 600
Red probe on B and Black on E, Should read about 600

Testing for shorts between pins set MM to Buzzer and check
B + C
B + E
C + E
Probes both ways

I tested mine and got about 426 is that too far off?

[PlainBill]

Re: Dell E153FPB Back Light problem

So I read pretty much the entire thread and im afraid im still not sure where to start. I have the Dell E153FPB. When i turn on the LCD screen it flashes white for a second and then goes black. I cannot see any image on the screen but the LED power light stays on.
I tested the fuse PF751 with an ohm meter and it has resistance, so im thinking its not that.
I also flipped the board over and didnt see any cold solder joints, fixed a couple that were debatable.

Sorry if this is a double post. I couldnt look any longer lol

Start with post 31 of this thread and follow the same advice.

PlainBill

[EGuevarae]

Re: Dell E153FPB Back Light problem

How do i test capacitance of the caps? I have a multimeter...

I was referring to the specs of the actual caps installed, not the actual capacitance of the caps. If they are a known bad brand , suggestions of replacements would start flowing all over the place. That would be the first step for troubleshooting the board. Not all the problems are related to bad caps, but then again, bad caps can cause problems and interfere with troubleshooting, and as a general rule, if you are going to spend sometime with an open unit, it is usually viewed as a preventive measure, even if the caps are not failing but are of a brand that, under that conditions (heat and poor ventilation) would fail.
Also, again, look for bad solder because that units tend to have that problem, even if it is not easily visible with the naked eye.

[jschiefer]

Re: Dell E153FPB Back Light problem

How do i test capacitance of the caps? I have a multimeter...

[EGuevarae]

Re: Dell E153FPB Back Light problem

So I read pretty much the entire thread and im afraid im still not sure where to start. I have the Dell E153FPB. When i turn on the LCD screen it flashes white for a second and then goes black. I cannot see any image on the screen but the LED power light stays on.
I tested the fuse PF751 with an ohm meter and it has resistance, so im thinking its not that.
I also flipped the board over and didnt see any cold solder joints, fixed a couple that were debatable.

Sorry if this is a double post. I couldnt look any longer lol

Used a flashlight to see if the panel is on and image is displayed (you would not see it clearly if the CCFLs are off but if you don't have an image, it's not the inverter or tubes.
Post series/brand/capacitance of caps, and test each of the four c5707s in there.