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    #21
    Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

    Originally posted by tboxxx View Post
    Here (http://www.elexp.com/t_test.htm) it's said that to test "in circuit" I will need to unsolder one end.

    Thanks.
    No you don't have to unsolder anything. Measure everything as is first. If the readings are suspicious, then unsolder one leg.

    Yes, all those circled are diodes. To test a diode in circuit,

    a) put your multimeter in diode test mode
    b) put your black lead on one side and the red lead on the other - record reading
    c) reverse the leads - recording reading

    A good diode should read 0.3V to 0.7V in one direction and 0L in the other. If you get a reading in both directions, you will have to desolder one leg and retest to verify.

    Report all your measurements.
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      #22
      Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

      OK, here are some results about question 3.

      I used 2 multimeters: my personal Mastercraft 52-0060-2 (cheap one, from Canadian Tire for 20$ bundled) and the office one Meterman 37XR.
      Mastercraft does not show eng units during diode test and the scale is weird. Anyway, here are the results:
      Code:
      Diode | Meterman read1 | Meterman read2 | Mastecraft read1 | Mastercraft read2
FD1/2 |   0.145V  |   1.329V  |    122    |   Overrange
FD3/4 |   0.143V  |   1.256V  |    120    |   Overrange
FD5/6 |   0.142V  |   1.543V  |    119    |   Overrange
FD7/8 |   0.141V  |   0.737V*  |    122    |   1085*
      * means that with red lead to cathode it shows 1085, than I removed one lead and put it back and the next reading is 1020. Remove a lead and put it back - it shows 780..800. That's weird.

      4. 4 transistors J598 are good, no shorts between 1-2-3.
      6. 5 fuses on USB board are good (F1-F4, F19).

      Where are voltage regulators on 4. and 5.?
      Any ideas? Also, why two different meters shows different numbers?
      I will post next readings soon.
      Thanks
      Last edited by tboxxx; 03-10-2011, 10:40 PM.

      Comment

        #23
        Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

        4. If J033 is voltage regulator then it's OK, no short.
        5. If J023 and J032 are voltage regulators then they are good, no shorts.

        Comment

          #24
          Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

          Originally posted by tboxxx View Post
          Code:
          Diode | Meterman read1 | Meterman read2 | Mastecraft read1 | Mastercraft read2
FD7/8 |   0.141V  |   0.737V*  |    122    |   1085*
          * means that with red lead to cathode it shows 1085, than I removed one lead and put it back and the next reading is 1020. Remove a lead and put it back - it shows 780..800. That's weird.
          FD7/8 could be bad. Let's note that they could be bad and leave the soldered in for now. You may have to desolder them and test them out of circuit to verify at a later point.
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            #25
            Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

            Originally posted by tboxxx View Post
            4. If J033 is voltage regulator then it's OK, no short.
            5. If J023 and J032 are voltage regulators then they are good, no shorts.
            The voltage regulators (in yellow) will have to be tested to see if they output the correct voltage. Even though they are not shorted (which is good), they need to output the correct voltage.

            With power on and lcd plugged in, use a ground screw for your black proble. Put your multimeter on 20V DC. Then put your red probe on each pin of the voltage regulator. Report all voltages.
            Attached Files
            Last edited by retiredcaps; 03-11-2011, 02:34 AM.
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              #26
              Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

              Originally posted by tboxxx View Post
              Also, why two different meters shows different numbers?
              For diode testing, some multimeters use OL or "1" to indicate out of range. As long as the diode doesn't show the same reading in both directions, it is likely to be good.

              On this board, the diodes could be in "parallel" so the multimeter diode test threshold may not be enough to trigger the "0L" on the Meterman.

              I had a Meterman 15XP, but I gave it away to a relative for business use so I'm familiar with the Meterman brand. I have used an autoranging Canadian Tire multimeter.
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                #27
                Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                Originally posted by retiredcaps View Post
                The voltage regulators (in yellow) will have to be tested to see if they output the correct voltage. Even though they are not shorted (which is good), they need to output the correct voltage.

                With power on and lcd plugged in, use a ground screw for your black proble. Put your multimeter on 20V DC. Then put your red probe on each pin of the voltage regulator. Report all voltages.
                Do you mean ground screw on the metal base of the monitor (kind of AC ground, yellow-green wire) or ground of each voltage regulator?

                Comment

                  #28
                  Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                  Originally posted by tboxxx View Post
                  Do you mean ground screw on the metal base of the monitor (kind of AC ground, yellow-green wire) or ground of each voltage regulator?
                  Example of ground screw on each board circled in light blue.
                  Attached Files
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                    #29
                    Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                    Originally posted by retiredcaps View Post
                    Example of ground screw on each board circled in light blue.
                    I can see these screws. Should they be connected to the monitor metal base which is connected to yellow-green ground wire? In this case I cannot reach the pins of the regulators.

                    Comment

                      #30
                      Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                      OK, here are the results:

                      Code:
                      Regulator |  G  |  O  |  I  |
J023   |  0V  | 1.79V |  3.32V |
J032   |  0V  | 2.49V |  3.32V |
J033   |  0V  | Unstable| Unstable|
                      Unstable means the voltage changes from 1V to 3.5V all the time.
                      J033 is the one on the USB board.

                      Comment

                        #31
                        Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                        Originally posted by tboxxx View Post
                        Unstable means the voltage changes from 1V to 3.5V all the time.
                        J023 and J032 look correct. 1.8V and 2.5V DC are "normal" output voltages for a voltage regulator (3.3V DC is another popular one). There is something wrong with voltage coming into J033. It should be a steady reading.

                        There is a 12 pin U shaped connector that connects the logic and USB board.

                        Number them 1-12 on the USB board anyway you like. VERY CAREFULLY, measure each pin and report the voltages. Put your multimeter on 20V DC. Do not let the red probe slip as you may cause a short. Put the black on a ground screw again.
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                          #32
                          Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                          Originally posted by tboxxx View Post
                          Also, why two different meters shows different numbers?
                          Did some more research on this.

                          Some multimeters can read diode measurements up to 2.0V before showing 0L (out of range). My 2nd hand 20+ year old Fluke 75 is one of those multimeters.

                          For the Meterman 37XR, it looks like the threshold is 3.0V DC before it displays 0L as per

                          https://cdn.badcaps-static.com/pdfs/...dcfcdea073.pdf
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                            #33
                            Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                            12 U shape contacts to Ground:

                            Code:
                            Contact Pair    |  Voltage
TP31        |  18.82V  
TP32        |  -0.01V  
TP33...TP36     |  3.32V...0.00V  
NoName (Ground)   |  0.00V  
TP34...TP37     |  0.03V...1.54V  
TP33...TP38(Ground) |  0.03V...-0.01V
                            Any ideas? What is the next step?
                            Thanks.
                            Attached Files

                            Comment

                              #34
                              Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                              Originally posted by tboxxx View Post
                              Any ideas? What is the next step?
                              Those voltages look okay on the U connector.

                              I suspect J033 is bad. The possibilities are

                              1) J033 itself is bad.
                              2) The components (possibly capacitors) feeding the voltage to J033 are bad.

                              Question. What is the full part number for the J033 chip? I know it is a voltage regulator, but I don't know what the output should be to find a replacement.
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                                #35
                                Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                                Another idea I had is to use the Meterman 37XR to read the capacitance of the capacitors on the USB board. Set the 37XR to 4000uF

                                Let's measure everything "in circuit" first (no desoldering of things). For each cap on the USB board, report the following like the example below.

                                C123 - 470uF 25V, measures 3300uF
                                C145 - 330uF 25V, measures 333uF

                                I know some of these readings will not make sense because the capacitors could be in parallel and/or series and it is best to desolder them and measure them out of circuit, but let's start with "in circuit" first.

                                For measuring uF, put your black probe to the negative lead of the cap (the stripe) and red probe to the positive lead of the cap.
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                                  #36
                                  Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                                  Originally posted by retiredcaps View Post
                                  Question. What is the full part number for the J033 chip? I know it is a voltage regulator, but I don't know what the output should be to find a replacement.
                                  J033 is 960T63

                                  Comment

                                    #37
                                    Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                                    Originally posted by tboxxx View Post
                                    J033 is 960T63
                                    The datasheet is here

                                    http://www.alldatasheet.com/datashee.../G960T63U.html

                                    It looks like a 3.3V 1A low dropout regulator.
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                                      #38
                                      Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                                      I tried to measure caps "in circuit" on USB board, but every time I was getting 0L on my multimeter (tried black probe to a negative lead of the caps and vice versa).

                                      Comment

                                        #39
                                        Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                                        I reread the Meterman 37XR datasheet and it says 400uF. I thought it was 4000uF so the 0L readings make sense.
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                                          #40
                                          Re: Dell 2007FPb No Power, Power and 1 icon (VGA) blinking

                                          Oh, I see. I have another multimeter at work (not Mastercraft and Meterman). Will check with that one.

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