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    LED Circuit Aluminum Base

    This is a LED circuit from a Outdoor light. One of the diodes has failed and I am wondering if that would cause that complete circuit plus the other two circuits to fail?? The DC voltage on the brown and grey contacts of all three boards is not stable?? It is jumping between 150 volts and 85 volts (not just one reading) that can't be normal?? but what would cause the voltage to be like that?? The Driver rating is 120 volts AC input/80v DC Output so I am guessing I should be reading a consistent 80 volts DC on all three light boards??
    Attached Files
    Last edited by davg; 05-04-2019, 09:53 AM.

    #2
    Re: LED Circuit Aluminum Base

    The LED driver in the bass is most likely a current limiting Supply. If you have a failed LED and it is moving between some sort of connectivity and none, the voltage might be rising as of the LED driver tries to raise the voltage to raise the current going through the LEDs. Does this problem occur if you short out one side of the LED that has failed to the other? (as in, bypass the failed led completely) Would you things work normally after that? Also, a picture of the bored and the back of the board where the traces are would be helpful if shorting out the LED does not help. Additionally, getting the number off of the driver IC would help us understand what could be going on a lot better.
    Last edited by Retro-Hipster; 05-04-2019, 09:51 AM.


    “Men always seem to think about their
    past before they die, as though they were
    frantically searching for proof that they
    truly lived.”
    – Jet (Cowboy Bebop) -

    Comment


      #3
      Re: LED Circuit Aluminum Base

      Thanks for the reply Retro-Hipster. I can stick my meter probe into the burnt out LED and I assume I'm hitting + and - on the board?? That one circuit will light up but the other two will not?? Not sure how to bypass the burnt out LED don't see any access to the contacts?
      I will get some pictures of the board front and pack and post them at the same time locate the # on the IC

      Comment


        #4
        Re: LED Circuit Aluminum Base

        Q1 is a HFS5N60U

        Comment


          #5
          Re: LED Circuit Aluminum Base

          The power supply is designed to limit the current once it reaches a certain value.
          However, because that particular led is faulty, the circuit is either open (no connection between the leds where that faulty led is) or closed (the led is shorted and behaves like a wire between + and -, or behaves like a resistor)

          If the led is open, the chain of leds is broken.
          The power supply starts with a low voltage and keeps increasing the voltage while monitoring the current consumed - it tries to reach the precise voltage when the current reaches a certain value, let's say 100 mA

          So let's say each led consumes 6v (two diodes inside the led each with 3v forward voltage) and you have 10 leds, so there's basically 20 diodes with 3v forward voltage, so 60v.
          If everything was right, the power supply starts at a low voltage and quickly goes up and when it gets to around 60v, the leds start lightning and current flows and once that 100mA of current is measured, the power supply keeps the voltage at that 60v level.
          As the leds warm up their forward voltage may change a bit, like for example it may go down to around 2.8v ... so now the leds only need 10 leds x 2 diodes per led x 2.8v forward voltage per diode = 56v

          Without any adjustment, as the forward voltage of the diodes inside leds goes down, each led consumes more current and gets hotter. However, the power supply detects this increase in current and reduces the voltage to 56v or to whatever voltage is needed to measure again only 100mA going through the chain.

          That's how these power supplies work.

          The first step you should do would be to desolder that faulty led. Easiest would be to heat the circuit board from the bottom (using a hair dryer for example, or a paint stripping gun) and once it's hot, you could use a soldering iron on the sides of the led to add a bit of solder and then push the led off the board.

          If you don't care about the faulty led, another option would be to just get a flat screw driver and just rip the led off - put some pressure on the side with the screwdriver and the led should break off.

          As a temporary measure, you can simply solder a wire between the + and - pads where that faulty led was, and now you have the chain of leds again ... minus one led. So instead of 10 leds, you have 9 leds.

          The power supply should still monitor the current and keep it to that preset value and should simply output less voltage.

          Comment


            #6
            Re: LED Circuit Aluminum Base

            Ah! What Mari said. Haha actually made a quick video to explain what I meant by shorting out the LED to see if the voltage becomes stable again, but I think that Mari said it more clearly than my video. LOL

            One thing to note, since it does look like each of the three panels are in parallel it would mean that the voltage essentially wouldn't adjust quite as far down as you might otherwise prefer for the panel with the missing LED. So basically, it would still be over driving the other LEDs in comparison to the panels that aren't damaged, but how much it is over driving would be up to how much current is actually going to the panel and up to the actual rating of the LEDs. I hope this helps. (I doubt it would make a serious difference..)

            Well, if you wanted to see the video still, here it is. Haha
            https://youtu.be/carVjaQ-qoM
            Last edited by Retro-Hipster; 05-04-2019, 01:32 PM.


            “Men always seem to think about their
            past before they die, as though they were
            frantically searching for proof that they
            truly lived.”
            – Jet (Cowboy Bebop) -

            Comment


              #7
              Re: LED Circuit Aluminum Base

              Wow what a lesson you guys have an interment knowledge of such things I'm truly grateful to you both. I have to try to absorb some of this. I will post back the results. In post #3 I pointed out that by probing around inside the center of the burnt out LED I can get that board to light up (very bright) but the other two does nothing? does that mean the LED on these two boards are damaged?
              Great video Retro thanks for so much effort.

              Comment


                #8
                Re: LED Circuit Aluminum Base

                Here is what I would if I was doing this repair

                I would remove the LED board modules and check each one and this if you have a adjustable power supply

                What you need to check is what voltage and current do you get when the LEDs starts to light then slowly increase the voltage unit they start getting bright then check each module and see if you get the same results for other modules

                The one that has the burn out LED can not be checked that way until you remove this LED and jump it out now your voltage will NOT be the same all your interested in is if the other LEDs light and if your current is the same

                It also looks like the yellow capacitor has a hole in unless that is a black dot

                Now I can not tell what type of LED light you have someone else will have to help you with that
                Last edited by sam_sam_sam; 05-04-2019, 08:05 PM.
                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


                  #9
                  Re: LED Circuit Aluminum Base

                  Oh... That's an interesting one.. Just to confirm, do those three led panels seem to be wired in parallel? It looks like there is a positive and negative wire going from the driver board into wire nuts and then, from there, into the three led panels.

                  If that's the case then it could have something to do with the one panel with the failed led clamping down the voltage and dumping the current into the remaining LEDs on that panel. That's just a guess for sure, but it would be interesting to know if removing that damaged led panel from the equation caused the other two LED panels to light up. That being said, I wouldn't expect this situation to be happening normally. Maybe the driver IC sort of just raises the voltage until it starts to conduct and then intelligently bumps up the current based on the number of LEDs? Not sure.. Regardless, this one seems pretty interesting!

                  As for the LED size, if you measure it with some measuring device like calipers it should be pretty easy to tell what type it is, like a 5050smd size. (5mmx5mm). If you figure out what voltage it starts to light at you will be able to tell what configuration the chips inside the board are and how many there are. (ie: 2 chips in parallel equaling 5-6 volts) I'm thinking about the power supply bit assuming the panels take about 5 volts a chip and you have 12 LEDs a panel, you would need about a 60 volt supply to get them to light if you tested them individually. (That's why I ended up using a capacitive dropper in my video.. My dc supply goes to 40ish volts.)
                  Last edited by Retro-Hipster; 05-04-2019, 08:17 PM.


                  “Men always seem to think about their
                  past before they die, as though they were
                  frantically searching for proof that they
                  truly lived.”
                  – Jet (Cowboy Bebop) -

                  Comment


                    #10
                    Re: LED Circuit Aluminum Base

                    Originally posted by davg View Post
                    The Driver rating is 120 volts AC input/80v DC Output so I am guessing I should be reading a consistent 80 volts DC on all three light boards??
                    This is possible that would make each LED would about 6.6 volts
                    Because 6.6 X 12 = 79.2 volts very close 80 volts

                    Look at the yellow capacitor and see if there is a hole in it or is that a black dot
                    Last edited by sam_sam_sam; 05-04-2019, 08:06 PM.
                    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


                      #11
                      Re: LED Circuit Aluminum Base

                      Originally posted by Retro-Hipster View Post
                      Well, if you wanted to see the video still, here it is. Haha
                      https://youtu.be/carVjaQ-qoM
                      I like this video very nice

                      I have one comment and that is I would not short out the LED unless he has a Incandescent light bulb in series with the LED light fixture for safety reasons because you do not know if this circuit works correctly or not

                      Plus the fact that you do not know how much current you are going to using when one LED is missing because if my calculations are correct 12 LEDs X 6.6 volts = about 80 volts output

                      So if you short one LED would each LED would see 7.7 volts so how much more would each LED see in current hard to say exactly
                      Last edited by sam_sam_sam; 05-04-2019, 08:37 PM.
                      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


                        #12
                        Re: LED Circuit Aluminum Base

                        Originally posted by davg View Post
                        Q1 is a HFS5N60U
                        What is controlling the mosfet

                        It has to have some type of switching regulator to control the mosfet

                        It might be on the bottom of the board because I do not see it on the top of the board
                        Last edited by sam_sam_sam; 05-04-2019, 08:46 PM.
                        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


                          #13
                          Re: LED Circuit Aluminum Base

                          Ah, well I'm glad you liked it Sam. Lol I thought the video was pretty fumbly myself. :') But yes, I kind of assume that, with it being a current limited supply that it SHOULD keep things from going too crazy, but that's definitely why I always have a current limiting bulb in circuit with the stuff I work on..

                          But yes, the actual chip number should help a lot davj. and it looks like there are a lot of us wanting to help with this mystery!


                          “Men always seem to think about their
                          past before they die, as though they were
                          frantically searching for proof that they
                          truly lived.”
                          – Jet (Cowboy Bebop) -

                          Comment


                            #14
                            Re: LED Circuit Aluminum Base

                            [QUOTE=sam_sam_sam;894903]Here is what I would if I was doing this repair

                            I would remove the LED board modules and check each one and this if you have a adjustable power supply
                            Thanks Sam I don't have an adjustable power supply


                            It also looks like the yellow capacitor has a hole in unless that is a black dot
                            That is a black dot

                            Comment


                              #15
                              Re: LED Circuit Aluminum Base

                              Originally posted by Retro-Hipster View Post
                              Oh... That's an interesting one.. Just to confirm, do those three led panels seem to be wired in parallel? It looks like there is a positive and negative wire going from the driver board into wire nuts and then, from there, into the three led panels.

                              If that's the case then it could have something to do with the one panel with the failed led clamping down the voltage and dumping the current into the remaining LEDs on that panel. That's just a guess for sure, but it would be interesting to know if removing that damaged led panel from the equation caused the other two LED panels to light up. That being said, I wouldn't expect this situation to be happening normally. Maybe the driver IC sort of just raises the voltage until it starts to conduct and then intelligently bumps up the current based on the number of LEDs? Not sure.. Regardless, this one seems pretty interesting!

                              As for the LED size, if you measure it with some measuring device like calipers it should be pretty easy to tell what type it is, like a 5050smd size. (5mmx5mm). If you figure out what voltage it starts to light at you will be able to tell what configuration the chips inside the board are and how many there are. (ie: 2 chips in parallel equaling 5-6 volts) I'm thinking about the power supply bit assuming the panels take about 5 volts a chip and you have 12 LEDs a panel, you would need about a 60 volt supply to get them to light if you tested them individually. (That's why I ended up using a capacitive dropper in my video.. My dc supply goes to 40ish volts.)
                              Thanks again Retro your observation on the wiring is correct + and - to the wire clamp than to the three boards. That being said If I removed the board with damage do I need to substitute a load to prevent damage to the other two boards? Or would is the driver be intelligent enough to control it?

                              Comment


                                #16
                                Re: LED Circuit Aluminum Base

                                If the power supply is setup as one constant current source to supply the current to all the LED strings (in your case 3 LED strings), so if the power supply is setup to drive 300mA of constant current through the load then each LED string will get 100mA each (Vf of LED strings are matched), now if one goes open circuit, the the other two will then get 150mA each since power supply will try to maintain constant 300mA of current flow through the load. If one string has shorted out LEDS then that string will draw the most current.
                                You should verify the total current draw from the power supply is and then check the current draw of each LED string.
                                If the power supply is setup as constant Voltage source then if one string goes open circuit then it will not cause the other two string to draw more current because the power supply will maintain constant Voltage.
                                You can easily do the experiment with CC/CV power supply and some LED's. It is never really good idea to direct drive parallel the LED due to variation in Vf of the LED's.
                                Your power supply looks to be CV type not CC, but if you can provide us with good clear pictures of the board then that will help the verififcation, you can also verify but vary the the load to see how the power supply reacts.

                                https://www.led-drivers.com.au/avoid...river-parallel

                                http://lednique.com/parallel-leds/

                                https://forum.digikey.com/t/led-wiri...xoCJa0QAvD_BwE
                                "Keep in mind when an LED(s) burns out, gets damaged, or is cut from a strip in a combinational constant current circuit that the remaining LEDs may be damaged, as the fixed current may be too high for the remaining LEDs. This is yet another reason constant voltage drivers are easier to work with and usually preferred for series-parallel combinational circuits"

                                https://www.arrow.com/en/research-an...ds-in-parallel
                                Last edited by budm; 05-05-2019, 05:19 PM.
                                Never stop learning
                                Basic LCD TV and Monitor troubleshooting guides.
                                http://www.badcaps.net/forum/showthr...956#post305956

                                Voltage Regulator (LDO) testing:
                                http://www.badcaps.net/forum/showthr...999#post300999

                                Inverter testing using old CFL:
                                http://www.badcaps.net/forum/showthr...er+testing+cfl

                                Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                                http://s807.photobucket.com/user/budm/library/

                                TV Factory reset codes listing:
                                http://www.badcaps.net/forum/showthread.php?t=24809

                                Comment


                                  #17
                                  Re: LED Circuit Aluminum Base

                                  Some pic of the front and back of the board. The # on the IC is LD7832GR 1434FC
                                  Attached Files
                                  Last edited by davg; 05-06-2019, 06:26 AM.

                                  Comment


                                    #18
                                    Re: LED Circuit Aluminum Base

                                    looks like you have at least 1 led bad on each board.
                                    i would replace all leds with ones from a major brand.
                                    and this gives you the opportunity to select color temp and cri.
                                    the issue is that 1 goes open and takes that module out.
                                    this raises the current to the other 2 by 33%.
                                    when the next one goes the remaining module is overdriven 3x.
                                    and when it loses a led that led gets fried when it opens due to the driver raising voltage in its attempt to hold the current setpoint.
                                    this would be the burnt one you see.

                                    Comment


                                      #19
                                      Re: LED Circuit Aluminum Base

                                      Tks kc8adu that is what it appears. With the known faulty board (with the burnt LED) removed there no attempt for the other two to light up? I wouldn't mind replacing all the LED's but are they available as a module? where are they available? What major brand?

                                      Comment


                                        #20
                                        Re: LED Circuit Aluminum Base

                                        Originally posted by davg View Post
                                        Thanks again Retro your observation on the wiring is correct + and - to the wire clamp than to the three boards. That being said If I removed the board with damage do I need to substitute a load to prevent damage to the other two boards? Or would is the driver be intelligent enough to control it?
                                        Ah, Basically, just what Budm said. haha

                                        Essentially, it could damage the other two panels. If the panel with the burnt out LED doesn't light up on it's own (without shorting the bad LED out), then it's not going to be drawing anything anyways. That is actually good enough confirmation as it were. When the panel with the bad LED is not lit, do the other two panels light up? Sorry, I know you have been a bit bombarded with questions and whatnot by me. ahaha


                                        “Men always seem to think about their
                                        past before they die, as though they were
                                        frantically searching for proof that they
                                        truly lived.”
                                        – Jet (Cowboy Bebop) -

                                        Comment

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