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    Re: Dell E172fpb

    So I found out the hissing noise is coming from the biggest transformer (T601), or along that area. I measured the resistance of the primaries and secondaries and it seems they yield no resistance? I was measuring the voltages at the 100uf cap (biggest cap) and the voltages are at 165V. I still get 400+V at teh CCFL connection but drops to 2V after a few seconds or so. None of the trannies get hot this time, so I assume no voltage are going through them. Are those voltages normal? Am I out of luck?
    Last edited by DJ XtAzY; 02-17-2010, 01:47 PM.

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      Re: Dell E172fpb

      Originally posted by DJ XtAzY
      So I found out the hissing noise is coming from the biggest transformer (T601), or along that area. I measured the resistance of the primaries and secondaries and it seems they yield no resistance? I was measuring the voltages at the 100uf cap (biggest cap) and the voltages are at 165V. I still get 400+V at teh CCFL connection but drops to 2V after a few seconds or so. None of the trannies get hot this time, so I assume no voltage are going through them. Are those voltages normal? Am I out of luck?
      165 volts is normal at the big cap if your line voltage is 120 VAC. Don't bother trying to measure the resistance of the SMPS transformer. An inverter transformer should show some resistance - probably about 1 ohm on the primary, and about 1K on the secondary.

      Please clarify one thing. You indicated the green power button shuts off after about 10 seconds. Is this with signal present?

      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.

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        Re: Dell E172fpb

        Yes. Let me give you exact details. So I plug the cord into the board while using my extension cord switch to turn the monitor on and off. Here are the results from my observation:

        The green light shuts off after 30 seconds. 50 seconds after that, that hissing noise from that area. I switch it off and wait about a minute. Turn it on and the green light lights up for 13 seconds and the hissing sound will come shorty. It green light doesnt flicker either, like it did when it first died. The only hottest component I can feel without touching is IC701, but with that huge heatsink, I assume it suppose to be hot. I compared the resistance measurement with the inverter transformer and the results is simliar to the other post #52 in earlier pages.

        And let just say I find it fun repairing this thing, which is why i don't want to give up!

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          Re: Dell E172fpb

          Also is the Genesis chip suppose to be hot or warm? And now the Power button don't even respond, like if i want to turn the monitor off.

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            Re: Dell E172fpb

            Sorry for triple posting (cant edit post?) but when i measure the voltages on diodes like D761, I can see that the voltages slowly dropping.

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              Re: Dell E172fpb

              Update: Upon testing, I just realized the logical board isnt working anymore. Upon turning on, I get weird display where it's all pink and random colors. After that it shuts off. The Genesis chip gets really hot to touch, so does that shut off the inverter board too? I just ordered another one but I'm afraid that will die too after a couple of testing.

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                Re: Dell E172fpb

                Just to give another update: I replaced the logic board and now it's fine. So I guess it was the logic board that was messed up, which was causing the hissing noise and stuff. Right now I'm just testing the monitor without assembling back to the case just to monitor temperatures. The Genesis chip gets hot but still ok to touch compared to my old one. Maybe I'll put a heatsink on it. The transistors are very hot to touch, but I remember that removing resistor R750 helps. Does it really lower temperatures? I don't care if the brightness setting doesnt work, but not sure if it really lower temperatures. I did remove it before but that was with my old logic board and nothing shown up on the screen with that removed. So i thought that destroyed my logic board. Can anyone confirm this?

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                  Re: Dell E172fpb

                  Hello,

                  There seem to be a number of issues being dealt with in this thread which is unfortunate. I am writing to address the issue of the blinking power button and the flashing screen (on-off 2sec cycle). I have this problem and I replaced the transistors as described in other places. The issue I have is that it seemed to work fine for a while but then gradually over the period of a month... it would take longer and longer to turn on, while doing the flashing thing while during the startup wait. Interestingly enough, if I could leave the monitor on for several days and it would be fine. The issue appears to only appear during the CCFL lighting procedure. This would make sense to me if either the lamps are worn out and (I'm not very familiar with CCFL operation) causing more current to be drawn than designed causing either the feedback circuitry to kill it or the resulting damage to the rest of the board due to the increased loading. Has anyone tried replacing the CCFLs in the monitor ? I searched and didnt find any indication that this has been tried other than a short reference in this thread. I believe that replacing the CCFL's in conjunction with another transistor swap will be my next effort.

                  Thoughts?

                  E.

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                    Re: Dell E172fpb

                    bump

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                      Re: Dell E172fpb

                      bumpbump

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                        Re: Dell E172fpb

                        Originally posted by eventnick
                        Hello,

                        There seem to be a number of issues being dealt with in this thread which is unfortunate. I am writing to address the issue of the blinking power button and the flashing screen (on-off 2sec cycle). I have this problem and I replaced the transistors as described in other places. The issue I have is that it seemed to work fine for a while but then gradually over the period of a month... it would take longer and longer to turn on, while doing the flashing thing while during the startup wait. Interestingly enough, if I could leave the monitor on for several days and it would be fine. The issue appears to only appear during the CCFL lighting procedure. This would make sense to me if either the lamps are worn out and (I'm not very familiar with CCFL operation) causing more current to be drawn than designed causing either the feedback circuitry to kill it or the resulting damage to the rest of the board due to the increased loading. Has anyone tried replacing the CCFLs in the monitor ? I searched and didnt find any indication that this has been tried other than a short reference in this thread. I believe that replacing the CCFL's in conjunction with another transistor swap will be my next effort.

                        Thoughts?

                        E.
                        What have you done with the power supply board? You mentioned replacing the transistors. Did you also resolder the transformers? Have you replaced the electrolytic capacitors? Given that a complete recap will cost in the order of $10.00 and the CCFLs cost about $10 each, a recap seems to be in order.

                        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


                          Re: Dell E172fpb

                          Originally posted by PlainBill
                          What have you done with the power supply board? You mentioned replacing the transistors. Did you also resolder the transformers? Have you replaced the electrolytic capacitors? Given that a complete recap will cost in the order of $10.00 and the CCFLs cost about $10 each, a recap seems to be in order.

                          PlainBill
                          ^^ What he said--you need to also resolder the transformers. Replacing the transistors only treats the symptom. I've fixed a fair number of this model monitor, and have only seen one or two monitors with blown caps. The rest all had blown transistors due to bad solder joints on the transformers.

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                            Re: Dell E172fpb

                            On top of BJT's, you should reflow the cracked joints along inverter-transformers leads.

                            Comment


                              Re: Dell E172fpb

                              I picked up a Dell E193fpb today and it wouldn't power on at all. Took it apart (bugger to pry it open with minimal damage) and noticed no obvious bulges on caps.

                              Turned the power board around and noticed the AC solder was really bad (brownish color, obvious cold joint). Resoldered and now it works!

                              And yes, I left all the Capxon caps onboard (even though I know it is bad brand). I'll replace them next time?

                              Sorry, I had to use the flash so the pic isn't all that great.

                              Originally posted by gina0602
                              On top of BJT's, you should reflow the cracked joints along inverter-transformers leads.
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                                Re: Dell E172fpb

                                Originally posted by retiredcaps
                                I picked up a Dell E193fpb today and it wouldn't power on at all. Took it apart (bugger to pry it open with minimal damage) and noticed no obvious bulges on caps.

                                Turned the power board around and noticed the AC solder was really bad (brownish color, obvious cold joint). Resoldered and now it works!
                                Wow, I've seen a few questionable solder joints, but those are just inexcusable!

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                                  Re: Dell E172fpb

                                  Replaced 4x C5707 and the 2x other transistor normally sold on ebay as a kit.
                                  It worked for 2 days then stopped, wack on the side got it to work for a few seconds then off again.
                                  I resoldered the transformers and will order another ebay kit. Wish I read this thread before I changed the transistors.

                                  Great thread, too bad this monitor is crap.

                                  Will post when I get the new parts.

                                  Max

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                                    Re: Dell E172fpb

                                    Originally posted by maxosd
                                    Replaced 4x C5707 and the 2x other transistor normally sold on ebay as a kit.
                                    It worked for 2 days then stopped, wack on the side got it to work for a few seconds then off again.
                                    I resoldered the transformers and will order another ebay kit. Wish I read this thread before I changed the transistors.

                                    Great thread, too bad this monitor is crap.

                                    Will post when I get the new parts.

                                    Max
                                    Resolder everything suspicious and then install the new transistors. Maybe not all of them fried again. You can test them if you have a multimeter. Those that work can help you troubleshoot other units.
                                    Eduardo
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                                      Re: Dell E172fpb

                                      On the one I fixed (using it as I type) the thing that made it all of a sudden after running through the hoops and making it behave was a solder joint under the copper ground foil. This looked right but when you thumped the chassis it would make and brak the connection. Took a few days of chasing to narrow it down to the area and it looked fine visually other than a slight bt of dull solder. I hit it with the iron and it has been working absolutley perfectly for over a year now.

                                      The only reason I even thought to do that was someone had mentioned the age of these and the possibility of them being built during the transition to lead free solder. That was trickier stuff when it first showed up and have seen a lot of crap joints as a result of it not being done correctly.

                                      Anyway something else for you to check before you throw it over the cliff

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                                        Re: Dell E172fpb

                                        Wow.... This thread has been going for 4 years now! I have 2 of these monitors that i've kept as spares for friends or family when they've had problems with their own. I borrow them these and then fix the ones they have. Oddly enough, these are BY FAR the most pain in the @$$ monitors/inverter boards i've tried to fix. The Samsungs are by far the easiest because it's usually 3 specific caps that are domed.

                                        Anyway... Mine worked one day, and wouldn't the next time it was powered up. There were no warning signs in between which was odd. When it gets plugged in, I see a faint flicker of the monitor. The power button also flashes on/off about every 1 second. I'm no electronics expert by ANY means. I don't even know how to read a test-o-meter thingy. I DO, however, have a good eye and with the help of an LED magnifying glass, I can spot bad solders rather quickly. Right now, there are 3 VERY orange-ish solders on the back of my inverter board. The rest are very clean looking and solid.

                                        I'm going to resolder those specific spots and see what happens. All my caps are nice and flat, which was also odd. I usually expect to see at least one that's domed. If all else fails, I did find many replacement inverter boards on evilbay for $40 or so...


                                        Here goes nothing.

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                                          Re: Dell E172fpb

                                          The orange color could be left over flux residue from the original factory solder process.

                                          I suggest you post pics of your boards (see FAQ) before buying replacement boards on ebay for $40 for 3 reasons.

                                          1) Here in Canada, you can buy used working LCD 19 inch monitors sometimes for $40.

                                          2) Fixing a component on the board may only cost you $2 or $3 versus $40.

                                          3) $40 is WAY TOO MUCH to pay for an used inverter board.

                                          PS. Here is a good site for what a good/bad solder joint looks like.

                                          http://workmanship.nasa.gov/lib/insp...uirements.html

                                          Originally posted by rokkaholik
                                          Right now, there are 3 VERY orange-ish solders on the back of my inverter board.

                                          If all else fails, I did find many replacement inverter boards on evilbay for $40 or so...
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                                          If you are new to this forum, we can help a lot more if you please post clear focused pictures (max resolution 2000x2000 and 2MB) of your boards using the manage attachments button so they are hosted here. Information and picture clarity compositions should look like this post.

                                          We respectfully ask that you make some time and effort to read some of the guides available for basic troubleshooting. After you have read through them, then ask clarification questions or report your findings.

                                          Please do not post inline and offsite as they slow down the loading of pages.

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