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Checking bridge rectifier D25XB60

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  • Checking bridge rectifier D25XB60

    I have tested this bridge and I do get reading where it should be reading and I have open circuit where it should be open. The question I have is: I have seen on YouTube and read around that readings should be between 400 and 600. My readings are all much higher like 1871.. I bought a new Bridge and got the same readings!!!!??? SO are high readings OK? Or my DMM is bad, but I don't think it is, it works OK with single diodes, resistors and other functions..

  • #2
    What are the units? mV?
    What's the part/model number of the bridge?
    Can you put new batteries in your meter to see if the readings change?

    - any/all of these will help determine the right answers to your questions.
    If it still won't get loud enough, it's probably broken. - Steve Conner
    If the thing works, stop fixing it. - Enzo
    We need more chaos in music, in art... I'm here to make it. - Justin Thomas
    MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

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    • #3
      Make sure your meter is in diode test mode as you won't get a sensible reading with anything else. If your meter works fine with a single diode then it should work with a bridge as you're just testing 4 individual diodes. You should get a reading of about 0.6v for each diode in the forward direction.

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      • #4
        The name/ model is in the thread name D25XB60, DMM is set for diode checking - continuity mode. Will try new battery..

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        • #5
          If you bought another new bridge and it reads the same, then the bridge is probably ok.
          So just a question about your meter, or whether it is some odd type of bridge.
          Originally posted by Enzo
          I have a sign in my shop that says, "Never think up reasons not to check something."


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          • #6
            I tried with the fresh battery, the readings are the same... And btw if DMM is set for continuity (diode test) aren't the units Ohms? Why are people saying mV?

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            • #7
              Here is datasheet if anybody can figure out
              Attached Files

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              • #8
                So the fwd voltage drop from the sheet is typically 0.7vdc, what we expect from one diode drop. If you are measuring across two diodes (from + to -, for example, or ~ to ~) you'd probably read 1.3..1.6vdc, that might explain what you see?

                To check each diode individually, you'll want 4 separate diode readings (eight measurements total), so from + to ~, for example, and then reverse the leads and repeat. Then from + to the other ~ terminal, and so on. 4 of the readings should be infinity, represented by OL or a very large number, and 4 should be the diode drop of .7vdc as expected.
                If it still won't get loud enough, it's probably broken. - Steve Conner
                If the thing works, stop fixing it. - Enzo
                We need more chaos in music, in art... I'm here to make it. - Justin Thomas
                MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

                Comment


                • #9
                  No, in diode test the reading is not in ohms. In diode test the reading is voltage drop across the junction. The reading is in volts. For a diode, typically 0.4v to 1v.
                  Education is what you're left with after you have forgotten what you have learned.

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                  • #10
                    Originally posted by eschertron View Post
                    So the fwd voltage drop from the sheet is typically 0.7vdc, what we expect from one diode drop. If you are measuring across two diodes (from + to -, for example, or ~ to ~) you'd probably read 1.3..1.6vdc, that might explain what you see?

                    To check each diode individually, you'll want 4 separate diode readings (eight measurements total), so from + to ~, for example, and then reverse the leads and repeat. Then from + to the other ~ terminal, and so on. 4 of the readings should be infinity, represented by OL or a very large number, and 4 should be the diode drop of .7vdc as expected.
                    Yes, I have been measuring correctly it's just that my readings are high, I am getting a new DMM tomorrow, even on a single diode it's giving readings over 1800's I never paid attention.. I suspect cheap DMM, I will know more tomorrow. Thanks :-)

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                    • #11
                      Originally posted by Enzo View Post
                      No, in diode test the reading is not in ohms. In diode test the reading is voltage drop across the junction. The reading is in volts. For a diode, typically 0.4v to 1v.
                      Duly noted, thank you :-) I am getting a new DMM tomorrow, this one is showing readings in 1800's even for any random diode i take of the table..

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                      • #12
                        So if it measures the same as other diodes, and a new one also measures same, it should be ok.
                        Meantime, what is the unit you are trying to fix and what is the fault?
                        Originally posted by Enzo
                        I have a sign in my shop that says, "Never think up reasons not to check something."


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                        • #13
                          Got new DMM everything perfect, sorry for the confusion, trowing away old DMM in the garbage

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                          • #14
                            Originally posted by g1 View Post
                            So if it measures the same as other diodes, and a new one also measures same, it should be ok.
                            Meantime, what is the unit you are trying to fix and what is the fault?
                            I'm working on the switching power supply from Behringer PMP5000 but I have a separate thread on that here you go https://music-electronics-forum.com/...ad.php?t=49735

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