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    #41
    Re: Testing a transformer

    We have to determine why the fuse blew...

    Step 1
    Replaced fuse. Plugging in board blows fuse F201. Replace fuse and Go to Step 1B

    Set VOM Multimeter to 2k OHM scale:
    Step 1B
    Resistance on Diode Bridge BD201 (2KBP06M):
    1-2, 1-3, 1-4, 2-3, 2-4, 3-4 (Pin 4 is at the top, Pin 1 at the bottom, 3-prong socket facing me)
    (Red <+> lead on lower pin number, OHMs) 1.03k,0.0,958,open,1.05k, 953
    (Black <-> lead on lower pin number, OHMs) open, 0.0, open, 1.02k, open, open

    Pins 1-3 are shorted.

    Step 2.
    Resistance of Power FET Q201 (Reads B 644 / FQP / 8N60C, a FPQ8N60C?)
    1-2, 1-3, 2-3. (Pin 2 is across the slot from the other two pins)
    (Red <+> lead on lower pin number, OHMs) open, 1.96k, open
    (Black <-> lead on lower pin number, OHMs) open, 1.09k, 945

    Q201 is OK

    Step 1B1. Electrical continuity check. Set VOM Multimeter to audible or an OHM scale:
    Trace each flat prong to Pin 3 of diode bridge BD201
    OK left side, OK right side.

    Need for BD201 replacement at the very least.

    Thank you. This gives me hope for repairing this monitor. Sorry for the delay in answering. Should I obtain any other component?

    Comment

      #42
      Re: Testing a transformer

      Originally posted by tglenchur
      We have to determine why the fuse blew...

      Step 1
      Replaced fuse. Plugging in board blows fuse F201. Replace fuse and Go to Step 1B

      Set VOM Multimeter to 2k OHM scale:
      Step 1B
      Resistance on Diode Bridge BD201 (2KBP06M):
      1-2, 1-3, 1-4, 2-3, 2-4, 3-4 (Pin 4 is at the top, Pin 1 at the bottom, 3-prong socket facing me)
      (Red <+> lead on lower pin number, OHMs) 1.03k,0.0,958,open,1.05k, 953
      (Black <-> lead on lower pin number, OHMs) open, 0.0, open, 1.02k, open, open

      Pins 1-3 are shorted.

      Step 2.
      Resistance of Power FET Q201 (Reads B 644 / FQP / 8N60C, a FPQ8N60C?)
      1-2, 1-3, 2-3. (Pin 2 is across the slot from the other two pins)
      (Red <+> lead on lower pin number, OHMs) open, 1.96k, open
      (Black <-> lead on lower pin number, OHMs) open, 1.09k, 945

      Q201 is OK

      Step 1B1. Electrical continuity check. Set VOM Multimeter to audible or an OHM scale:
      Trace each flat prong to Pin 3 of diode bridge BD201
      OK left side, OK right side.

      Need for BD201 replacement at the very least.

      Thank you. This gives me hope for repairing this monitor. Sorry for the delay in answering. Should I obtain any other component?
      No. You seem to have done a thorough job of testing. It is fairly common to find a blown fuse and a shorted rectifier and have the monitor working properly after replacing both of them. There IS a possibility of a defective SMPS controller, but that cannot be tested without replacing the fuse and rectifier.

      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

        #43
        Re: Testing a transformer

        My goodness, you respond quickly.

        I wanted to add that IC201 (Reads LD7575PS / 0630AH) is a D7575PS, PWM Controller? for others following this thread. Thank you again.

        Tom G.

        Comment

          #44
          Re: Testing diode bridge and FET - epilogue

          Success. Replacing the T3 fuse and 2KBP206 diode bridge returned the LCD monitor to service. You were right. Thank you for helping me through this repair.

          By the way, while shopping for diode bridge replacements I saw KBP206 ( no leading 2) with the same amperage and voltage ratings as the original 2KBP206 I was replacing. The data sheets show they differ in withstanding repeated voltage peaks. How critical are these differences and could I have used them as replacements?

          Tom G

          Comment

            #45
            Re: Testing diode bridge and FET - epilogue

            Originally posted by tglenchur
            Success. Replacing the T3 fuse and 2KBP206 diode bridge returned the LCD monitor to service. You were right. Thank you for helping me through this repair.

            By the way, while shopping for diode bridge replacements I saw KBP206 ( no leading 2) with the same amperage and voltage ratings as the original 2KBP206 I was replacing. The data sheets show they differ in withstanding repeated voltage peaks. How critical are these differences and could I have used them as replacements?

            Tom G
            I wouldn't worry about it unless you are planning on using the computer on 240 VAC in an area with a lot of voltage spikes.

            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

              #46
              Re: Testing a transformer

              Hi everyone. I am the new kid on the block. I also have a Mag Monitor 2200w with bad caps and transitors along with over heating.

              My question is: Is there a repair kit for this monitors power adapter? I have the same unit as what tglenchur has been fighting with.

              David

              Comment

                #47
                Re: Testing a transformer

                Originally posted by handitech View Post
                Hi everyone. I am the new kid on the block. I also have a Mag Monitor 2200w with bad caps and transitors along with over heating.

                My question is: Is there a repair kit for this monitors power adapter? I have the same unit as what tglenchur has been fighting with.

                David
                No. With a DMM you can determine which parts are bad and replace them. Note that tglenchur 's monitor took a power surge and was readily repairable. There are places on eBay that will repair the power supply / inverters for many monitors, however the repair and shipping charges make it uneconomical in most cases. As an example, the caps to rebuild a 17" Gateway monitor cost under $10, with shipping. Xxxx on eBay wanted $35 plus return shipping to repair the power supply.

                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

                  #48
                  Re: Testing a transformer

                  Point Taken. Ebay is not always full of great deals.

                  Just finished replacing the lamps in a HP w2207h. The bottom lamp had a micro crack in it and all the powder leaked out.
                  Besides marriage I would say that was the most test of patience I have ever had. It was worth it though...like marriage. It has a really crisp view to it. Excellant for digital photography.

                  Time to celebrate. Ttyl
                  David

                  Comment

                    #49
                    Re: Testing a transformer

                    I also have this monitor and am having the staying on for 5 seconds then the backlight turning off. Can anyone ID these FETs? (i think that's what the are). I think that's what's bad on mine, as the CCFLs look good.. all white. I replaced all the caps.
                    edit: just realized stephkre had his CCFLs turned on to see the reddish tint. I never powered it up while the LCD was apart. Man, that this is a pain. I'm guessing that's what it is also.

                    Last edited by Eleazar; 09-07-2010, 10:26 PM.

                    Comment

                      #50
                      Re: Testing a transformer

                      Originally posted by Eleazar View Post
                      Can anyone ID these FETs? (i think that's what the are). I think that's what's bad on mine,
                      Please don't post images inline because it slows down the loading of pages. Use the manage attachments.

                      Also, I don't see how testing a transfomer subject fits your problem. If you have a problem, start a new thread.

                      You can test the FET by the following.

                      If you have a manual range multimeter, set it to 200 ohms (two hundred). You can test a mosfet (Q, IC designation) or fet "in circuit" by (power off and unplugged)

                      a) black on pin 1- red on pin 2 - record ohms
                      b) black on pin 1- red on pin 3 - record ohms
                      c) black on pin 2- red on pin 3 - record ohms

                      If any ohm reading is less than 50 ohm you might have shorted mosfet. Remove from circuit and repeat the tests to verify.
                      --- begin sig file ---

                      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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                      Comment

                        #51
                        Re: Testing a transformer

                        Mosfet data sheet as follows:-
                        http://pdf1.alldatasheet.com/datashe.../PHD3055E.html

                        These Fet's do run hot, and the 'discolouration' on the board from heat, is NOT excessive in my opinion !!

                        Comment

                          #52
                          Re: Testing a transformer

                          Sorry about my less than thoughtful first post. My problem seems to be similar or the same as the original poster. Red tint, not as bright, goes off after 5 seconds. Thanks for finding that datasheet Rtech. I will test the mosfets before openning the panel.

                          off-topic: I had no idea badcaps.net had a forum. I remember when it was just a page showing how to repair motherboards with bad caps. Seems to be a great resource now!

                          Comment

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