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    #21
    Re: Dell 1800fp

    Originally posted by junktv View Post
    Unless you mean voltage at + side.
    Yes, I mean measuring DC voltage for both caps.

    Black probe on negative leg of cap. Red probe on positive leg of cap. This is measuring the DC voltage across the legs of the cap.

    Repeat for other cap.
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      #22
      Re: Dell 1800fp

      I'm not sure this is correct since i was getting wierd readings.

      At first on the ic i was reading .40-.45 between 6 and 7 pin. When i rechecked it after the caps i got 11.45-12.08.

      C924 showed 0v until i switched to 2000m from 20v and then showed 003.

      C907 showed .55 average but jumped to 11.45-12.05.

      All fluctuated or would continually drop when showing the lower numbers other than C924 which stayed the same.

      Comment

        #23
        Re: Dell 1800fp

        Originally posted by junktv View Post
        At first on the ic i was reading .40-.45 between 6 and 7 pin. When i rechecked it after the caps i got 11.45-12.08.

        C907 showed .55 average but jumped to 11.45-12.05.

        All fluctuated or would continually drop when showing the lower numbers other than C924 which stayed the same.
        Okay, we have 3 likely possibilities for your fluctuating voltage.

        1) The startup cap C907 is bad. It doesn't have to bloat in order to be bad.

        2) The SMPS IC is bad.

        3) There is something shorted on the output side to cause the fluctuating voltage. I would suspect one or more of the three diodes on the secondary side. These 3 diodes are mounted on the aluminum heatsink and are likely marked with the letter Dxyz.

        Test each one of these diodes with your multimeter on the diode test function. If the diode looks like this -><-, you should have 4 readings per diode. You don't have to remove the diodes in order to test them. If the readings look suspicious, then you will have to remove them and verify out of circuit.

        Start with #3 first.
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          #24
          Re: Dell 1800fp

          Lost me. On the heatsinks there is a q902 near the ice chip which i think is a transister. Directly across on the seperate sink is a d906 and d903 with >l< symbal.

          Off the heat sink is a d901 and d902 near the ice chip. Also a d907 just below ic901 in the pic.They have a l< which is what i think the diode funtion on my meter is.

          Do i still test with power? Sorry not sure how to do this.
          Attached Files
          Last edited by junktv; 02-10-2012, 08:06 PM.

          Comment

            #25
            Re: Dell 1800fp

            "Q" is a transistor. "D" is a diode. We only want to test the diodes.

            Let's try this. On all the chips that have a "D", follow this procedure.

            1) Set your multimeter on diode test.

            2) Power off the TV and unplug it. Wait 5 minutes.

            3) For a 2 pin diode, put your black probe on one end, red on the other. Record the reading. Now reverse the probes and record the reading.

            4) For a 3 pin diode, number the pins 1, 2, and 3. It doesn't matter which side is 1.

            pin 1 - black probe, pin 2 - red probe
            pin 2 - black probe, pin 1 - red probe
            pin 3 - black probe, pin 2 - red probe
            pin 2 - black probe, pin 3 - red probe
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              #26
              Re: Dell 1800fp

              D907 = 095
              D901 = 480
              D902 = 507

              D903 looking at bottom non power cord plug side and left to right.
              1-2 = keeps climbing
              2-1 = 180
              3-2 = keeps climbing
              2-3 = 180
              1-3 = 001

              D906
              1-2 = climbs
              2-1 = went from 102-104 after a couple seconds
              3-2 = climbs
              2-3 = started negative then 100 and slowly climbed and steadied at 104
              1-3 = 001

              Comment

                #27
                Re: Dell 1800fp

                Originally posted by junktv View Post
                D907 = 095
                D901 = 480
                D902 = 507
                For the above, you should two readings each. Reverse the probes for the second reading.

                Double, triple check D907.
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                  #28
                  Re: Dell 1800fp

                  Originally posted by retiredcaps View Post
                  For the above, you should two readings each. Reverse the probes for the second reading.

                  Double, triple check D907.
                  Ah sorry. Both the same for D907 and the other read infinite when reversed.

                  Comment

                    #29
                    Re: Dell 1800fp

                    Originally posted by junktv View Post
                    Ah sorry. Both the same for D907 and the other read infinite when reversed.
                    Desolder D907 and retest out of circuit. If it is the same reading both ways, it is bad.
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                      #30
                      Re: Dell 1800fp

                      If there are any ZD in the same area, they are zener diodes and should be tested as well.
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                        #31
                        Re: Dell 1800fp

                        Originally posted by retiredcaps View Post
                        If there are any ZD in the same area, they are zener diodes and should be tested as well.
                        ZD901 = 801/infinite

                        ZD902 which some have mentioned would save the IC901 is missing.

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                          #32
                          Re: Dell 1800fp

                          Anyone have a suggestion for what series caps to use to replace these? I see they are all general but they use two different kinds so must be different specs. I was going to try and find them all in panasonic and i think Fc was a good general cap. Might order a ICE 2as01 also. Or do you think my problem is some where else on the PSU?

                          PSU
                          1x 50v 47uf sam young KMG
                          1x 10v 2200uf KMG
                          1x 25v 33uf samwha RG
                          1x 16v 1000uf RG
                          2x 10v 2200uf samwha RD
                          2x 16v 2200uf RD

                          Logic
                          1x 25v 470uf samwha RD
                          1x 25v 470uf sam young KMG

                          http://www.samyoung.co.kr/download/miniature/KMG.pdf
                          http://www.soselectronic.com/a_info/...e/a/pdf/RD.pdf

                          I have some extra 25v 470uf rubycon ZL if they will work for either of the 2 on the logic card.
                          http://www.rubycon.co.jp/en/catalog/...minum/e_zl.pdf

                          Thanks

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                            #33
                            Re: Dell 1800fp

                            Originally posted by junktv View Post
                            Or do you think my problem is some where else on the PSU?
                            1) Did you change out D907? You said it had the same reading both ways.

                            2) If this monitor has been used 6 years 24/7, then

                            365 x 24 x 6 = 52560 hours.

                            Your ccfls are likely near end of life. From my research, they last anywhere from 40k to 60k. If this were my monitor, I would just replace the diode, and retest. If it works fine, leave the caps in and use the monitor until the ccfls start to die.
                            Last edited by retiredcaps; 02-13-2012, 02:19 PM.
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                              #34
                              Re: Dell 1800fp

                              Ah i forgot to do that. I'll get to it here in a few and report back.

                              True but i am hoping it works alot longer and only $10-15 in parts w/ shipping.

                              Good clear monitor and can run dual pc's.



                              EDIT: D907 is 638 and infinite.
                              Last edited by junktv; 02-13-2012, 03:08 PM.

                              Comment

                                #35
                                Re: Dell 1800fp

                                Originally posted by junktv View Post
                                EDIT: D907 is 638 and infinite.
                                D907 is good with those readings out of circuit.

                                I would change C907 first then. If the voltage still fluctuates, then your SMPS IC might be bad.
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                                  #36
                                  Re: Dell 1800fp

                                  Can you recommend a good series match from panasonic for that cap and the others? I don't know how to figure out the ohm and ripple when they don't have it listed.

                                  It's $5 shipping if i order one or all of them anyway and never hurts having extra parts laying around. Unless like now none are of the same values i happen to need other than a couple and they are low esr i think. Hopefully that fixes it ,the last PSU i worked on was two of the sink mounted resistors that was bad.

                                  Comment

                                    #37
                                    Re: Dell 1800fp

                                    Originally posted by junktv View Post
                                    Can you recommend a good series match from panasonic for that cap and the others? I don't know how to figure out the ohm and ripple when they don't have it listed.
                                    If there are no datasheets for the originals, I would just get Panasonic FR or FM as the first choice (either is fine). If the values don't exist for those 2 series, then choose Panasonic FC.

                                    The SMPS IC is only available on ebay.

                                    http://www.ebay.com/sch/?LH_PrefLoc=1&_kw=ice2as01
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                                      #38
                                      Re: Dell 1800fp

                                      Well i found a PDF for the samwha RG on this site.HERE

                                      Seen the bottom number where it shows dimensions is the ripple so that helps.

                                      Comment

                                        #39
                                        Re: Dell 1800fp

                                        Does this look like it will work? I wasn't sure what to get for the RG 25v 33uf. It looks like they have a series M, KG and GA that are in the specs that i could figure out. Would one work better than the other?

                                        In my list the ones in brackets () are other series available. From column I left are the original specs.

                                        RG datasheet
                                        KMG
                                        RD
                                        Attached Files

                                        Comment

                                          #40
                                          Re: Dell 1800fp

                                          Originally posted by junktv View Post
                                          I wasn't sure what to get for the RG 25v 33uf.
                                          When ESR or impedance is not listed, it is a general purpose cap. The datasheet even says general purpose.

                                          So you want ripple at least 75ma or more. I would get this Pansonic one (75ma)

                                          http://search.digikey.com/us/en/prod...491-ND/2504580

                                          The rest look okay.
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