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    #21
    Re: Dell monitor

    Originally posted by cb92 View Post
    There is 8mv between pin 6&7 on the IC. Same across cap c907.
    Try this quick check. With power off and monitor unplugged, set your meter on resistance and measure across pins 6 & 7 of the ICE2AS01. If you measure a short, then the chip is bad.

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      #22
      Re: Dell monitor

      D902 checked out ok. But r902 has 38v in and 28 v out, and r903 has 28v in but only 8mv out....that goes to pin 6 on the chip, so...maybe that resistor is bad, even though it measures the correct resistance of 38k ohms?

      connected to the board pin 6 to pin 7 is 11 ohms (the chip)
      Last edited by cb92; 01-07-2012, 09:04 PM.

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        #23
        Re: Dell monitor

        Originally posted by cb92 View Post
        D902 checked out ok. But r902 has 38v in and 28 v out, and r903 has 28v in but only 8mv out....that goes to pin 6 on the chip, so...maybe that resistor is bad, even though it measures the correct resistance of 38k ohms?

        connected to the board pin 6 to pin 7 is 11 ohms (the chip)
        The resistance you got between pins 6 and 7 indicates a short circuit. This, however, does NOT necessarily mean that the ICE2AS01 PWM chip is bad. It could be diode D902, too! You said it measured "OK". But did you test diode D902 out of circuit or in circuit? - it really matters now.

        If you tested diode D902 in circuit, then there's no way you'll know whether the ICE2AS01 PWM chip is bad or diode D902 is bad, especially because of the resistance you got (11 Ohms) which is very close to the value of R907. Therefore, you now HAVE TO remove D902 and test it out of circuit. When testing it out of the circuit, you should get a reading only in one direction when using the diode test function. If you get a reading in both directions, IT IS BAD. If diode D902 checks good, then it's definitely the ICE2AS01 PWM chip.

        And no, R902 and R903 cannot be bad if they measure proper resistance.

        Comment

          #24
          Re: Dell monitor

          D902 passed the out of circuit test.
          I lifted the leg of r903 to pin 6, and it has about 80 vdc on it disconnected, 8mv connected. Seems like the chip is pulling the circuit down. I pulled the chip, and there is 10 ohms between 6 and 7. 15 ohms fro 7 to 5. 20 ohms from 7 to 3. 7 to 1,4,8 are open.
          I'll see if Radio Shack has an ICE2A501. If this is a common chip, I'll get a couple while I'm there.

          Comment

            #25
            Re: Dell monitor

            Originally posted by cb92 View Post
            I'll see if Radio Shack has an ICE2A501.
            They will NEVER find it if you don't give them the correct part number.

            ICE2AS01

            S as in Santa, not the number 5.

            Plenty on ebay for $3 each or 2 for $4.75.
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              #26
              Re: Dell monitor

              A common failure on this power board is the ICE2AS01. It's caused by bad solder joints on the main transformer and duo diode packs (the two packs mounted on the heatsink). Therefore, remember to resolder all the pins on these devices, or you'll be replacing the ICE2AS01 again.

              Your best bet for replacing the ICE2AS01 is Ebay, since it's a obsolete chip no longer made by Infineon.
              Last edited by jetadm123; 01-08-2012, 06:40 PM.

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                #27
                Re: Dell monitor

                Thank goodness for E-bay. I'll get the parts to make my optoisolator tester, too. I've been collecting parts as I go.

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                  #28
                  Re: Dell monitor

                  Just something else to drive me crazy. Apparently optoisolators come in two sizes, normal and wider. The wider ones won't fit into a chip socket, so I'll modify one* for my tester, and have both sizes on the tester (*chip socket).
                  Meanwhile, all the optos I ordered from e-bay are probably the small size...luckily a standard one will just fit into the holes a wide one comes from. I sure hope I get a variety in case optos are made with different values. Still learning. Luckily, they are cheap, but it takes forever to get anything in the mail here. Aargh.

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                    #29
                    Re: Dell monitor

                    The chips are in, and that was the problem. I put a power supply in from E-bay, the one I fixed is a spare, good for testing 5v and 12v stuff. From this exercise I now have an optoisolator tester (see 'Instructables', "Altoid box optoisolator tester", a little power supply, and a lot of good experience.
                    Thanks one and all for the help. I now is an expurt.

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