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    #1

    Dell E177FPf No Power

    Hello. Great Forum. I have 2 Dell E177FPf LCD Monitors. One has a damaged screen, so I'm only trying to get 1 to work. Both show same signs... appears to have no power... no LED on/off light etc...

    I'll call the monitors "A" and "B".

    I started by replacing most of the caps for both power boards (I like to do this, even if they are good. It keeps them from coming back to me later with a bad cap issue. Cheap insurance).

    Monitor "A". When plugged in, you can hear one of the transformers (I think) charging up and then ticking over and over. No display at all. No LED light at all. Pushing buttons does nothing.

    Monitor "B". When plugged in, you can hear something charge up... but no ticking. NO display at all. No LED light at all. Pushing buttons does nothing.

    Voltage checks:

    Filter Capacitor: "A" = 155VDC. "B" = 155VDC

    Supply Voltage of power IC (U850): "A" = moving from 12.3 to 16.2VDC... cycling all over the place. (I circled the Power IC in red in one of the pics of this board.) "B" = 16.6VDC steady (believe this is correct).

    Supply voltage from video section(U802): "A" = 0.69VDC steady. "B" = 3.3VDC steady (I circled this in red on same photo.)


    I only need to get one monitor working... and would like to take good parts from one board and replace them on the other... but I"m lost from here. Any help? Any other checks to see?

    Thanks
    Attached Files
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    #2
    Re: Dell E177FPf No Power

    Originally posted by billy66 View Post
    I started by replacing most of the caps for both power boards (I like to do this, even if they are good. It keeps them from coming back to me later with a bad cap issue. Cheap insurance).
    Odd, that you would only change most, but not all given how inexpensive the caps are. See

    https://www.badcaps.net/forum/showth...ainbill+burned

    Monitor "A". When plugged in, you can hear one of the transformers (I think) charging up and then ticking over and over.
    Ticking suggests that the SMPS is trying to start.

    Monitor "B". When plugged in, you can hear something charge up... but no ticking. NO display at all. No LED light at all. Pushing buttons does nothing.

    Voltage checks:

    Filter Capacitor: "A" = 155VDC. "B" = 155VDC
    155V DC just meets the threshold. If you are 110V * 1.4, that is 154V DC. 155V DC just barely makes it.

    Supply Voltage of power IC (U850): "A" = moving from 12.3 to 16.2VDC... cycling all over the place. (I circled the Power IC in red in one of the pics of this board.) "B" = 16.6VDC steady (believe this is correct).
    For A, the fluctuating voltage suggests that one of the little caps either C852 and/or C856 (hidden underneath that white glue) are bad. These caps are likely to be 1 to 4.7uF 50V and 22 to 47uF 50V.

    I suggest working on "A" first and then "B". For "A" change out those 2 caps listed above and retest. Once "A" works, we can work on "B".

    PS. Great pics.
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    Comment

      #3
      Re: Dell E177FPf No Power

      Thanks retiredcaps.

      I usually only change the larger caps on the power supply, as I've found that in 80% of the monitors I've fixed... these were always bad. I've never (and I know eventually it will happen) found the smaller ones to be bad. I have a good supply of the larger ones on hand, so it is easier. I just fix these monitors for friends and family currently. I've been picking up broken ones to learn on, and then giving them to people. So to keep my costs down, and not pay shipping on every order of new caps... I ordered the larger ones in bulk to save.

      I've read before that the ticking suggest the SMPS is trying to start... but didn't know where to go from there.

      If the 155VDC is at the threshold, might I have an issue here too?

      C857 is the tall cap under glue: 10uf 50v
      C856 is the tiny surface mount
      Which did you mean?

      C852 is the large gray box cap... is this the one you mean?

      I've took a close up photo.

      I've read a lot on these forums and it has helped a lot. One thing I have read over and over is "please include pics".

      Thanks for the help!
      Attached Files

      Comment

        #4
        Re: Dell E177FPf No Power

        Originally posted by billy66 View Post
        If the 155VDC is at the threshold, might I have an issue here too?
        Let's assume it is good for now, but we will note it may be a problem.

        C857 is the tall cap under glue: 10uf 50v
        C856 is the tiny surface mount
        Which did you mean?

        C852 is the large gray box cap... is this the one you mean?
        Replace C857 for sure (10uF 50V). Do not replace C856 or C852. These tend to be more reliable type of capacitors versus electrolytics.

        If you don't have a spare or new 10uF 50V, take it from "B" and retest board "A".

        This is only for testing and you should get a new low ESR cap afterwards. The cap from "B" should work fine since it is providing stable voltage to the SMPS.

        One thing I have read over and over is "please include pics".
        It helps a lot which is why I write very specific instructions regarding clear focused pictures.
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        Comment

          #5
          Re: Dell E177FPf No Power

          On board A, you seem to have installed 2 caps together at C871... was this because you didn't have the correct capacitor?
          How have you installed them? Looks like there could be a chance the legs may be shorting on each other?

          Comment

            #6
            Re: Dell E177FPf No Power

            Good work so far, with the exception of failing to replace C857. This cap provides start-up power to the smps. They fail without any obvious sign (except the ticking).

            On monitor 'B' the problem is most likely to be the serial eeprom with the red dot next to the gm2621-LF. That stores the firmware.

            Pers Haanson describes his efforts with a similar problem that was resolved by reloading the eeprom. Perhaps we should launch an effort to locate the firmware; I have a monitor with the same problem.

            PlainBill
            For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

            Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

            Comment

              #7
              Re: Dell E177FPf No Power

              Originally posted by seanc View Post
              On board A, you seem to have installed 2 caps together at C871... was this because you didn't have the correct capacitor?
              How have you installed them? Looks like there could be a chance the legs may be shorting on each other?

              I was also looking at those two caps. You probably were putting two caps in parallel to create a cap value you didn't have. What was the original value and what value did you use as a substitute?

              Comment

                #8
                Re: Dell E177FPf No Power

                I'll replace C857 (10uf 50v) on board "A" or swap with board "B". I'll try that today.

                C871 was 680uf 16v. I replaced it with a Panasonic FM series 470uf25v and a Panasonic FM series 220uf25V. I've checked and double checked to see if I shorted them, and they are fine. This board (A) was having the same problem prior to replacing this cap. I did this just to test, and will be getting the proper size to replace my handy work... I started by soldering the two caps together, testing, and then attaching to the board.

                Thanks PlainBill on the info about C857 and its job. Like I said, I'm learning (and having fun in the process).

                The serial eeprom? How hard/easy is it to reload the firmware? This is something I have not done before.

                All I need is to get one monitor up. The other has a damaged screen, so getting both boards working would only provide me a spare (and some learning). If there was someone who needed/wanted the other board, I could send it to them once I get one board running.

                Thanks again to all those who have helped so far, I'm learning already.

                Comment

                  #9
                  Re: Dell E177FPf No Power

                  Originally posted by billy66 View Post
                  I'll replace C857 (10uf 50v) on board "A" or swap with board "B". I'll try that today.

                  C871 was 680uf 16v. I replaced it with a Panasonic FM series 470uf25v and a Panasonic FM series 220uf25V. I've checked and double checked to see if I shorted them, and they are fine. This board (A) was having the same problem prior to replacing this cap. I did this just to test, and will be getting the proper size to replace my handy work... I started by soldering the two caps together, testing, and then attaching to the board.

                  Thanks PlainBill on the info about C857 and its job. Like I said, I'm learning (and having fun in the process).

                  The serial eeprom? How hard/easy is it to reload the firmware? This is something I have not done before.

                  All I need is to get one monitor up. The other has a damaged screen, so getting both boards working would only provide me a spare (and some learning). If there was someone who needed/wanted the other board, I could send it to them once I get one board running.

                  Thanks again to all those who have helped so far, I'm learning already.
                  Reloading the firmware is not a trivial task. Note that the chip has a colored dot; that would indicate it was important to distinguish between it and other physically identical chips. That leads me to the conclusion there is no provision for loading the firmware once it is soldered to the board.

                  Per Hansson describes the process he went through in this thread. He had a summary of the steps in post 50.

                  There are a number of obstacles in the process. Removing the chip from the board (Chip-Quik works well), obtaining a programmer (The Willem programmer Per Hansson refers to is one of the best, I believe some early Intel Ethernet cards would work as well), adapting the chip to the programmer (wires would work in a pinch), and obtaining the firmware. This last has baffled me.

                  I was not suggesting you actually do this, but rather pointing out that these monitors are known to have a problem where they do not work, even though the power supply is working and all voltages on the logic card are correct. As you pointed out, if you can get one card working you have succeeded.

                  PlainBill
                  For a number of reasons, both health and personal, I will no longer be active on this board. Any PMs asking for assistance will be ignored.

                  Never be afraid to try something new. Remember, amateurs built the ark. Professionals built the Titanic.

                  Comment

                    #10
                    Re: Dell E177FPf No Power

                    I swaped the caps... board acted exactly the same... but I can assume the other cap is good due to the fact that board "B" does not tick?

                    Comment

                      #11
                      Re: Dell E177FPf No Power

                      Originally posted by billy66 View Post
                      I swaped the caps... board acted exactly the same... but I can assume the other cap is good due to the fact that board "B" does not tick?
                      What is the voltage on U850? Is it stil fluctuating?

                      What is the part number for U850?
                      Last edited by retiredcaps; 09-27-2010, 11:00 AM. Reason: fluctuating
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                      Comment

                        #12
                        Re: Dell E177FPf No Power

                        This is a very interesting board, since the power supply, inverter and logic card are all integrated on the same board. Can you please give the part number for the 5-legged device (u801? covered by black mark) that's to the left of the ribbon cable connector.

                        Comment

                          #13
                          Re: Dell E177FPf No Power

                          U850: SG5841SZ
                          Voltage board A: 12.3 - 16.2VDC... leg 3 (this is with either cap)
                          Voltage board B: 16.6VDC steady.

                          Comment

                            #14
                            Re: Dell E177FPf No Power

                            Originally posted by billy66 View Post
                            U850: SG5841SZ
                            Voltage board A: 12.3 - 16.2VDC... leg 3 (this is with either cap)
                            Voltage board B: 16.6VDC steady.

                            On U850, can you also measure VDD, pin 7. This is tied to the startup circuit.

                            Comment

                              #15
                              Re: Dell E177FPf No Power

                              OK, this is weird. I measured pin 7 on U850 for board "A"... same as pin 3: 12.3-16.2VDC and moving. I then took cap C857 out of board "A" (this is its original cap) and put it on board "B" so I could test U850 to compare, and now board "B" is working. Not sure why, but maybe C857 was bad on board "B" all along? Or I could have a bad connection. I'm going to put it all together and test for a while. I will order up all new caps as suggested by the wise people here.

                              Comment

                                #16
                                Re: Dell E177FPf No Power

                                Originally posted by jetadm123 View Post
                                this is a very interesting board, since the power supply, inverter and logic card are all integrated on the same board. Can you please give the part number for the 5-legged device (u801? Covered by black mark) that's to the left of the ribbon cable connector.
                                u801: 1506 0634cl

                                Comment

                                  #17
                                  Re: Dell E177FPf No Power

                                  Originally posted by billy66 View Post
                                  and now board "B" is working. Not sure why, but maybe C857 was bad on board "B" all along? Or I could have a bad connection.
                                  Just to clarify, so now board "B" is working and you get a display?
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                                    #18
                                    Re: Dell E177FPf No Power

                                    Originally posted by billy66 View Post
                                    One has a damaged screen, so I'm only trying to get 1 to work.
                                    How damaged is the screen? Is it usuable as a backup LCD monitor if both boards are fixed?
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                                      #19
                                      Re: Dell E177FPf No Power

                                      "B" is working, get a display. Testing it for long run now. Make sure it works when heated up. Also will test it for repeatability, make sure it starts over and over.

                                      The other screen. Just tested with the good board. It is smashed on one side, and mostly white throughout the rest with small areas of the image. Are you interested in this monitor? I could put it together and mail it if you pay the shipping... I was going to just keep the board for spare parts, but feel more than happy sending it off to someone who has helped, if wanted.

                                      Comment

                                        #20
                                        Re: Dell E177FPf No Power

                                        Originally posted by billy66 View Post
                                        "B" is working, get a display. Testing it for long run now. Make sure it works when heated up. Also will test it for repeatability, make sure it starts over and over.
                                        Well, that is good news. You may have had a poor solder joint on that cap?

                                        Are you interested in this monitor? I could put it together and mail it if you pay the shipping... I was going to just keep the board for spare parts, but feel more than happy sending it off to someone who has helped, if wanted.
                                        Thanks for the offer, but I'll pass.

                                        Perhaps PlainBill can make use with just the eeprom chip from board "A"?
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