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Fish Tank LED Power Supply Gets Hot then shuts down

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    Fish Tank LED Power Supply Gets Hot then shuts down

    A good friend of mine brought to me a rather large LED light array that is used for fish tanks. IT's so large in fact, that it requires TWO ATX style power supplies.

    He told me that as soon as he turns it on, the LEDs turn on, but then shortly turn off.

    I tried powering the lights with just one power supply, but they wont power with just one, so with both turned on, the lights do turn on, but then they turn off.

    The power supplies are identical, and one of them seems just fine, but the other one ... within 10 seconds after connecting it to power, the two heat sinks get too hot to touch... so it seems like it might be shutting itself down before it burns itself out.

    Here are some pictures







    I understand a little about ATX power supplies ... that there's a high side and a low side and usually a PWM chip that drive a transformer and also usually a comparator chip that keeps an eye on voltage levels etc.

    Since one heat sink is on the high side and the other on the low side, its puzzling to me that both of them are getting that hot that quickly. And of course I'm not sure which fet on either heat sink is the one drawing all that current...

    Advice on how to move forward here to figure this out?

    Thank you,

    #2
    Re: Fish Tank LED Power Supply Gets Hot then shuts down

    More information about the LED is required. It's surprising to have one lamp powered by 12V or whatever directly, unless it was meant for off-grid use perhaps.

    Input/hot side has transistors on them and usually there are 2 plus one for standby.
    Output/safe side has all diodes on it pretty much.

    Some PSUs have protection to ensure you're not drawing too much but either way, as you increase load, it will dissipate more heat - both input and output side.

    I don't like high/low side because it could mean the high/low side transistor on the hot side to implement complementary drive.

    Comment


      #3
      Re: Fish Tank LED Power Supply Gets Hot then shuts down

      12v leds or 24v leds with psu's in series?
      or 5v leds?

      whats the wiring??

      Comment


        #4
        Re: Fish Tank LED Power Supply Gets Hot then shuts down

        Can we see the data plate for these switching power supply

        What I would do is work on the switching power supply that is having the issues of heating up very quickly but I would use some automotive head lamps as a load I would check each switching power supply individually and not together assuming that they are 12 volts each do they have a 5 volt power supply rail if so what does it power
        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


          #5
          Re: Fish Tank LED Power Supply Gets Hot then shuts down

          Originally posted by sam_sam_sam View Post
          Can we see the data plate for these switching power supply
          There is no data plate. Just this label which looks rather ... homemade to me ...




          Also, when I turn that power supply on WITHOUT a load connected to it ... the heat sinks of course do NOT get warm at all, but it does make this sound ... listen to all of it cause it gets more interesting about halfway through the audio.

          The noise is definitely coming from somewhere in the vicinity of the heat sinks.

          Also, the other power supply (the good one) does not make any noise when I power it up without a load. The chassis fan, however, does turn on.

          The "bad" power supply, the one making the noise, when I turn it on without a load, the chassis fan DOES NOT turn on, though I seem to remember it did turn on when it was under load though I can't be 100% certain on that.

          Originally posted by sam_sam_sam View Post
          What I would do is work on the switching power supply that is having the issues of heating up very quickly but I would use some automotive head lamps as a load I would check each switching power supply individually and not together assuming that they are 12 volts each do they have a 5 volt power supply rail if so what does it power
          Here are some more pics of the unit itself and the output side of the power supply. I haven't taken the circuit board out yet to start probing around. I wanted to gain some more knowledge first and get the opinion of you more experienced guys before I start taking things apart just to make sure Im proceeding in the most effective way possible.













          Last edited by EasyGoing1; 09-24-2022, 02:50 PM.

          Comment


            #6
            Re: Fish Tank LED Power Supply Gets Hot then shuts down

            Originally posted by stj View Post
            12v leds or 24v leds with psu's in series?
            or 5v leds?

            whats the wiring??
            Originally posted by eccerr0r View Post
            More information about the LED is required.
            See my most recent post.

            Comment


              #7
              Re: Fish Tank LED Power Supply Gets Hot then shuts down

              Looks like some dark looking LED’s… wonder if you got some bad ones? Test the individual string / individual LED’s with a bench PSU.

              Comment


                #8
                Re: Fish Tank LED Power Supply Gets Hot then shuts down

                Originally posted by CapLeaker View Post
                Looks like some dark looking LED's… wonder if you got some bad ones? Test the individual string / individual LED's with a bench PSU.
                Well I would if it weren't for this power supply that isn't working properly... 10 seconds after turning it on the heat sinks are too hot to touch. Yet the other power supplies heat sinks ae cool to the touch. Not to mention the noise the PS is making which I posted the audio here yesterday.

                Comment


                  #9
                  Re: Fish Tank LED Power Supply Gets Hot then shuts down

                  change all the small electrolytics.

                  Comment


                    #10
                    Re: Fish Tank LED Power Supply Gets Hot then shuts down

                    Originally posted by EasyGoing1 View Post
                    Well I would if it weren't for this power supply that isn't working properly... 10 seconds after turning it on the heat sinks are too hot to touch. Yet the other power supplies heat sinks ae cool to the touch. Not to mention the noise the PS is making which I posted the audio here yesterday.
                    What is the model number of the PSU? What IC's is it based on? I understand this light has 2 power supplies. One works good and the other one not? How are the PSU's hooked up to the 3 lights?

                    If I had to guess, I say the noise comes out of the big switching transformer between the two heat sinks. I would tear the PSU apart and check for cracked or dry solder joints.

                    Does this lamp (partially) run with only one PSU connected?

                    Comment


                      #11
                      Re: Fish Tank LED Power Supply Gets Hot then shuts down

                      Originally posted by stj View Post
                      change all the small electrolytics.
                      Did you listen to the sound file I posted?

                      Comment


                        #12
                        Re: Fish Tank LED Power Supply Gets Hot then shuts down

                        no, not interested.
                        the heat issue is first - it sounds like the driver transisters are being over-driven.
                        they are often driven through small blocking capacitors

                        Comment


                          #13
                          Re: Fish Tank LED Power Supply Gets Hot then shuts down

                          Originally posted by stj View Post
                          no, not interested.
                          the heat issue is first - it sounds like the driver transisters are being over-driven.
                          they are often driven through small blocking capacitors
                          Ive got an ESR meter ... would that not help in isolating the problem?

                          Also what would be causing the PS to shut off all on its own?

                          Comment


                            #14
                            Re: Fish Tank LED Power Supply Gets Hot then shuts down

                            Originally posted by CapLeaker View Post
                            What is the model number of the PSU?


                            Originally posted by CapLeaker
                            What IC's is it based on?
                            TWO ICs only





                            Originally posted by CapLeaker
                            I understand this light has 2 power supplies. One works good and the other one not? How are the PSU's hooked up to the 3 lights?
                            Through the two cords coming out of the housing each with a 4 pin round threaded connector ... reminds me of a CB Microphone connector from back in the day...




                            Originally posted by CapLeaker
                            If I had to guess, I say the noise comes out of the big switching transformer between the two heat sinks. I would tear the PSU apart and check for cracked or dry solder joints.

                            Does this lamp (partially) run with only one PSU connected?
                            No it does not run at all with only one power supply.

                            Comment


                              #15
                              Re: Fish Tank LED Power Supply Gets Hot then shuts down

                              Look at the PCB of the PSU if there is a brand and a model number printed on it. Could be along the edge or on a not so crowded area of the PCB.

                              Comment


                                #16
                                Re: Fish Tank LED Power Supply Gets Hot then shuts down

                                Originally posted by stj View Post
                                no, not interested.
                                the heat issue is first - it sounds like the driver transisters are being over-driven.
                                they are often driven through small blocking capacitors
                                I took out the big caps which are printed as 680uF

                                The meter reads one at 740uF and the other as 750 uF

                                Meter is a Fluke 17B

                                Comment


                                  #17
                                  Re: Fish Tank LED Power Supply Gets Hot then shuts down

                                  Originally posted by CapLeaker View Post
                                  Look at the PCB of the PSU if there is a brand and a model number printed on it. Could be along the edge or on a not so crowded area of the PCB.
                                  Only identifying markings on the PCB are these

                                  Comment


                                    #18
                                    Re: Fish Tank LED Power Supply Gets Hot then shuts down

                                    still trying to come to terms with how big this thing is or isn't. I recall my small 10 gallon fish tank only needing a small lamp, then when we're talking about a 40 gallon tank, a single F40T12 would be sufficient to illuminate it.

                                    Then there are LEDs now, those LEDs, 25 of them per set, so there's 75 of them total. If they were 1W a piece, 75 watts, that's a very bright lamp... but a single ATX-sized power supply should be more than sufficient.

                                    If they were 3W a piece, then 225W, which is REALLY bright, which a well designed single ATX-sized power supply is still sufficient, though 225W is a significant load but not unmanageable, a P4 with a GPU can get to 300W and we've had that for years.

                                    Then comes a 6A@120V power supply. I suppose that's inrush...but that's 720W...

                                    hmm...

                                    Comment


                                      #19
                                      Re: Fish Tank LED Power Supply Gets Hot then shuts down

                                      Originally posted by eccerr0r View Post
                                      still trying to come to terms with how big this thing is or isn't. I recall my small 10 gallon fish tank only needing a small lamp, then when we're talking about a 40 gallon tank, a single F40T12 would be sufficient to illuminate it.

                                      Then there are LEDs now, those LEDs, 25 of them per set, so there's 75 of them total. If they were 1W a piece, 75 watts, that's a very bright lamp... but a single ATX-sized power supply should be more than sufficient.

                                      If they were 3W a piece, then 225W, which is REALLY bright, which a well designed single ATX-sized power supply is still sufficient, though 225W is a significant load but not unmanageable, a P4 with a GPU can get to 300W and we've had that for years.

                                      Then comes a 6A@120V power supply. I suppose that's inrush...but that's 720W...

                                      hmm...
                                      So I learned a little about the company that designed these ... apparently they were quite the item back in the mid 2000's but another company ... some aerospace company had gotten a patent on marine aquarium lighting that I guess was close enough to this exact lighting system that they sued the company and put them out of business. The company, PFO - had been making and selling these LED lighting units long before this other company was awarded a patent.

                                      Its a shame ... They apparently had a good reputation as a company of quality and customer service.

                                      Also, when these lights turn on briefly, they are different colors and they are not very bright

                                      Comment


                                        #20
                                        Re: Fish Tank LED Power Supply Gets Hot then shuts down

                                        So since the two big caps are reading at around 750uF when they are supposed to be 680uF ... are they bad?

                                        Comment

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