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PLP-60-48 Single Output LED Power Supply - "chirping" noise

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    PLP-60-48 Single Output LED Power Supply - "chirping" noise

    Dear Badcaps forum members,

    Hope that you are all well!
    I am a newbie on a mission to figure out the cause of the PSU making a "chirping" noise:


    Having searched for this symptom online I have found some indication that failed capacitors may be an issue. To help with the troubleshooting, I have tried to isolate the problem and disconnected the PSU from the rest of the device - the chirping remained.
    I have then found that the whole PSU (apart from a small add-on board) can be replaced, and there is even a datasheet for it: https://cdn.badcaps-static.com/pdfs/...72e3c7c9cd.pdf

    I then removed the small add-on board and the PSU started without chirping:
    Click image for larger version

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    The output should have been 48V, but I don't know what to make of this reading (is it even indicative of the PSU health? perhaps only putting a proper load on it can tell).

    Once I re-attach the small add-on board (even without connecting the full load!) the chirping returns:
    Click image for larger version

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    The white terminal on this board connects to the PSU output and the red/black wires then feed the actual device.

    What could this behaviour mean? Is the problem in the add-on board? Can the presence of the add-on board create a sufficient load for the problem in the PSU to manifest itself?

    Thank you in advance!

    Tony

    #2
    the small board may regulate the current.
    it's a fixed but ajustable current supply, so the voltage can move around a bit.

    i would test the supply without the small board by using a light bulb - 25w or 40w, as it's only rated to 60w.
    a old style filament lamp - not a halogen or led etc.

    Comment


      #3
      Originally posted by stj View Post
      i would test the supply without the small board by using a light bulb - 25w or 40w, as it's only rated to 60w.
      a old style filament lamp - not a halogen or led etc.
      Thank you for the suggestion! You mean a 48v/25W filament light bulb would do for the test, correct? Does it have to be a 48V bulb or any filament bulb between 25-40W?
      Last edited by tester001; 12-06-2023, 09:39 AM.

      Comment


        #4
        240v is fine - only the wattage matters

        Comment


          #5
          I've connected the output of the PSU to an old projector bulb (8V 50W) and got the "chirping" again!
          Click image for larger version  Name:	image.png Views:	0 Size:	1.18 MB ID:	3158934

          Do any caps on this PSU look like they need replacement? If not, should I desolder them one-by-one and test using a capacitor meter?

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          Thank you for your help so far! Happy to carry out more tests and learn
          Last edited by tester001; 12-07-2023, 09:27 AM.

          Comment


            #6
            I have no clue of what I'm looking for, but I used the search on this website and found this:
            Click image for larger version

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            Does this mean that the pictured caps are bad and should be replaced?

            Comment


              #7
              8v lamp on a 48v supply?
              i'm kind of glad it didnt work or you would be sweeping up glass!
              you cant tell if a cap is good by looking, and YXF is low end for a psu - i would be using rubycon ZL or panasonic FR

              Comment


                #8
                Originally posted by stj View Post
                8v lamp on a 48v supply?
                i'm kind of glad it didnt work or you would be sweeping up glass!
                I read your '240v is fine - only the wattage matters' as 'voltage doesn't matter'

                Thank you, I will de-solder them and get them tested (will check online for methods)

                Comment


                  #9
                  Usually a chirping in the power supply means there is something shorted in the secondary, as the PSU starts, shuts down, starts again and shuts down again. Over and over, wash rinse, repeat.

                  Comment


                    #10
                    Originally posted by CapLeaker View Post
                    something shorted in the secondary
                    Sorry, I'm a total newbie. What does 'shorted in the secondary' mean?

                    Comment


                      #11
                      The low voltage side of the power supply. Just saying IF there is something wrong in the primary, it would have exploded in your face or there is an open circuit somewhere and is dead as a rock.
                      So the primary side works. The low power secondary has something wrong with it, Where does this little board hook up to… looks like into the secondary somewhere, as it got DC leads….
                      Last edited by CapLeaker; 12-08-2023, 05:27 AM.

                      Comment


                        #12
                        Originally posted by CapLeaker View Post
                        Where does this little board hook up to… looks like into the secondary somewhere, as it got DC leads….
                        It's an LED driver PSU

                        I've just tested the two 63V 470 uF capacitors:
                        one is reading 400 uF
                        the other 410 uF

                        Would this be sufficient to cause the described fault?

                        Comment


                        • sam_sam_sam
                          sam_sam_sam commented
                          Editing a comment
                          Did you test the capacitors off the board if not then remove them from the board and retest them

                        #13
                        in english - check the output diode

                        Comment


                          #14
                          Originally posted by stj View Post
                          in english - check the output diode
                          Thank you very much! After reading up more about the subject I found a diode next to the capacitors and it failed basic diode tests (wasn't passing current in any direction)

                          Datasheet: https://cdn.badcaps-static.com/pdfs/...1c6b8e6590.pdf

                          Shall I try to replace the fast recovery diode and put the capacitors back? Is it OK for 63V 470 uF capacitors to be reading 400 uF and 410 uF?

                          Thanks again!

                          Comment


                            #15
                            test the diode off the board,
                            if it's still bad then obviously replace it.
                            as for the caps, it really depends - if this is going somewhere hard to reach then it's better to replace the caps now than later.
                            but if it's easy to get to then i suppose it doesnt matter

                            Comment


                              #16
                              Something strange happened. I've been testing continuity with a Fluke meter and couldn't get any current flowing through the diode no matter how I connected the probes (in case I mixed up the polarity):
                              Click image for larger version

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                              Then a colleague tested the diode with this thingie and it now works correctly on Fluke too:
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                              So I'm back to situation where no components explicitly show as broken. But I think I may be getting the hang of the game: desolder and test everything..
                              Thank you for your continued help.

                              Comment


                                #17
                                If diodes fail, they like to fail short. The best way to test any component is to check it out of circuit.

                                Comment


                                  #18
                                  Originally posted by tester001 View Post

                                  I then removed the small add-on board and the PSU started without chirping:
                                  Click image for larger version  Name:	photo_2023-12-06_12-28-36.jpg Views:	479 Size:	199.8 KB ID:	3158286
                                  The output should have been 48V, but I don't know what to make of this reading (is it even indicative of the PSU health? perhaps only putting a proper load on it can tell).

                                  Once I re-attach the small add-on board (even without connecting the full load!) the chirping returns:
                                  Click image for larger version  Name:	photo_2023-12-06_12-38-01.jpg Views:	44 Size:	58.9 KB ID:	3158287
                                  The white terminal on this board connects to the PSU output and the red/black wires then feed the actual device.

                                  What could this behaviour mean? Is the problem in the add-on board? Can the presence of the add-on board create a sufficient load for the problem in the PSU to manifest itself?

                                  Tony
                                  I would focus on this little board

                                  Check the input pins ( the white pin connector) for a short if you find any thing lower than 500 ohms I would suspect I would go through the whole board what is the part number on the ic chip that has 4 pins on it would be the first thing I would check google search the part number to see what this device does and post it here so we can look at it as well

                                  Also what is the part number on the other ic chip that has 10 pins on it

                                  The voltage on the main board might be alright a few volts below because either it has no feedback which might come from the small board or this board needs a load on it to work correctly

                                  One way to check the main board for weather or not it is functioning correctly is to get 4 automotive tail light bulbs and wire them in series and see if the power supply complaint about its load if not then definitely focus on the little board for this issue that you have with it

                                  Can you please take another picture of the small board straight on and focus on the lettering so the image is clear so I can see the other components on the board thanks

                                  One note I am really interested in this little board to know what it's function is and how and what it does to the main board and how it effects the output of the main board ( my hunch is that it is the current controller board ) because the description of this switching power supply says that you are adjusting the current output
                                  Last edited by sam_sam_sam; 12-09-2023, 08:59 AM.
                                  9 PC LCD Monitor
                                  6 LCD Flat Screen TV
                                  30 Desk Top Switching Power Supply
                                  10 Battery Charger Switching Power Supply for Power Tool
                                  6 18v Lithium Battery Power Boards for Tool Battery Packs
                                  1 XBox 360 Switching Power Supply and M Board
                                  25 Servo Drives 220/460 3 Phase
                                  6 De-soldering Station Switching Power Supply 1 Power Supply
                                  1 Dell Mother Board
                                  15 Computer Power Supply
                                  1 HP Printer Supply & Control Board * lighting finished it *


                                  These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                                  1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                                  2 Hem Saw Computer Stack Board

                                  All of these had CAPs POOF
                                  All of the mosfet that are taken out by bad caps

                                  Comment


                                    #19
                                    i think the small board is a current regulation circuit.

                                    Comment


                                      #20
                                      Originally posted by sam_sam_sam View Post
                                      I would focus on this little board
                                      I think you are right, as I have just received a replacement PSU and I get the following results with it:
                                      PSU plugged into the mains and switched ON - no chirping
                                      little board soldered on - chirping starts


                                      Originally posted by sam_sam_sam View Post
                                      Check the input pins ( the white pin connector) for a short if you find any thing lower than 500 ohms I would suspect I would go through the whole board
                                      It is 290 Ohms!

                                      Originally posted by sam_sam_sam View Post
                                      what is the part number on the ic chip that has 4 pins on it would be the first thing I would check google search the part number to see what this device does and post it here so we can look at it as well
                                      Click image for larger version

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                                      02680
                                      PEm
                                      1551 B3
                                      6123

                                      I can't find the datasheet, but it appears to be something like this:
                                      Click image for larger version

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                                      Originally posted by sam_sam_sam View Post
                                      Also what is the part number on the other ic chip that has 10 pins on it
                                      Click image for larger version

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                                      54F4
                                      5022

                                      Originally posted by sam_sam_sam View Post
                                      The voltage on the main board might be alright a few volts below because either it has no feedback which might come from the small board or this board needs a load on it to work correctly

                                      One way to check the main board for weather or not it is functioning correctly is to get 4 automotive tail light bulbs and wire them in series and see if the power supply complaint about its load if not then definitely focus on the little board for this issue that you have with it
                                      Thank you for recommendation. Could I get away with connecting a 220v domestic filament light bulb to it?


                                      Originally posted by sam_sam_sam View Post
                                      Can you please take another picture of the small board straight on and focus on the lettering so the image is clear so I can see the other components on the board thanks
                                      Straight on the light was bouncing off, but I've managed to get the writing on the components in photos above. Here's an overall view:
                                      Click image for larger version

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                                      Thank you for your help!

                                      Comment

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