UV LED Device Repair

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • dennis_elx33
    Member
    • May 2019
    • 32
    • Malaysia

    #1

    UV LED Device Repair

    Hello Guys,

    Part Name: UV LED 365nm
    Problem Statement: LED intensity low

    I am repairing a UV LED lamp device. Found to have multiple burnt devices though I cannot identify what is this. Highly suspect that it is a resistor or a diode but i could not fully identify it because both resistance and diode test got OL result.

    Is there anyone here who knows what is it? or how can i test it?
    Attached Files
  • stj
    Great Sage 齊天大聖
    • Dec 2009
    • 30985
    • Albion

    #2
    Re: UV LED Device Repair

    are the leds in series?

    Comment

    • dennis_elx33
      Member
      • May 2019
      • 32
      • Malaysia

      #3
      Re: UV LED Device Repair

      Hello stj, yes, the leds are in series.

      What is the best way to check this unknown component?
      Last edited by dennis_elx33; 08-23-2023, 07:48 AM.

      Comment

      • stj
        Great Sage 齊天大聖
        • Dec 2009
        • 30985
        • Albion

        #4
        Re: UV LED Device Repair

        check a good one as a diode and see what the meter does.
        i am thinking it could be one of 2 things
        it could be a diode to protect from reverse polarity,
        or it could be a special device that bypasses dead leds.
        https://www.littelfuse.com/industrie...rotectors.aspx

        Comment

        • dennis_elx33
          Member
          • May 2019
          • 32
          • Malaysia

          #5
          Re: UV LED Device Repair

          Hi stj, sorry for the very late reply..

          I measured the unknown component using diode mode but there is no reading at all even forward and reversed bias. So do you think it is a special device instead of a diode?

          Comment

          • harp
            Badcaps Veteran
            • Jun 2022
            • 598
            • Planet Earth

            #6
            Re: UV LED Device Repair

            Maybe to check know good component with zener tester. It use higher voltage (can read higher voltage drop) and constant current.

            Is any reading of resistance, or capacitance can measure when desoldered from pcb? If it is a very high resistor, say 100M that is over range of your multimetar, you can do a trick: use 9v battery and see in voltage mode can it pass any voltage
            Or
            Use as much biggest resistor you can read with your multimeter (say 40M) and add this in parallel with it, then calculate resistance.
            Also, can you get picture of good component, not burned one, maybe some sign on it, or side shape...
            Last edited by harp; 09-26-2023, 09:15 AM.

            Comment

            • stj
              Great Sage 齊天大聖
              • Dec 2009
              • 30985
              • Albion

              #7
              Re: UV LED Device Repair

              i have never seen one of those led protectors, i have no idea how they react to test equipment

              Comment

              • eccerr0r
                Solder Sloth
                • Nov 2012
                • 8698
                • USA

                #8
                Re: UV LED Device Repair

                kinda doubt a completely open circuit would cause low intensity...

                Could you show a zoomed out picture of these elements with how they're connected with its LED and other LEDs? And perhaps others of the same element?

                Zener diodes should be a regular diode in one direction and seem to usually fail short.

                And as far as I can gather from the photos these are parallel with each LED? Did all of them burn?
                Last edited by eccerr0r; 09-26-2023, 10:34 AM.

                Comment

                • harp
                  Badcaps Veteran
                  • Jun 2022
                  • 598
                  • Planet Earth

                  #9
                  Re: UV LED Device Repair

                  Some link info

                  https://www.techbriefs.com/component...articles/14277

                  https://cieonline.co.uk/led-shunt-pr...lity-lighting/

                  Comment

                  • CapLeaker
                    Leaking Member
                    • Dec 2014
                    • 8126
                    • Canada

                    #10
                    Re: UV LED Device Repair

                    almost looks like a LED driver like an AL5809?

                    Comment

                    • eccerr0r
                      Solder Sloth
                      • Nov 2012
                      • 8698
                      • USA

                      #11
                      Re: UV LED Device Repair

                      harp is probably correct, this is for protecting against dead-open LEDs that would cause the whole array to go dark, So because of these failures probably a lot of the LED chips on that board probably have already failed with these devices and likely the whole board is probably ready for the scrap heap...

                      Comment

                      • dennis_elx33
                        Member
                        • May 2019
                        • 32
                        • Malaysia

                        #12
                        Re: UV LED Device Repair

                        Hi harp, really sorry for the very late reply. Been to other more urgent projects. Anyway, i have a photo attached here. As for your suggestion, i will try to do it. Thank you so much!

                        Hello eccerror, i couldn't identify if its parallel or series but the unknown devices (black color) are all open reading.
                        Attached Files
                        Last edited by dennis_elx33; 11-08-2023, 06:38 AM.

                        Comment

                        • dennis_elx33
                          Member
                          • May 2019
                          • 32
                          • Malaysia

                          #13
                          Re: UV LED Device Repair

                          Hello All,

                          One more problem is that i could not remove it using 2 soldering iron and even with the use of low temp soldering lead..

                          Also, tried to use a hot air blower but all unsuccess to remove.

                          And to make things worse, it is so fragile that even poking slowly by a tweezer, it breaks!

                          Any suggestion on this?
                          Attached Files

                          Comment

                          • harp
                            Badcaps Veteran
                            • Jun 2022
                            • 598
                            • Planet Earth

                            #14
                            Re: UV LED Device Repair

                            Yes, it is on huge heatsink... preheating will be required in order to desolder it.
                            Kitchen pot heater on bottom side (lowest temp about 150 - 180 dec C) and two solder iron/hotair from top side? It is heavy task...

                            And now I see... no nozzle, or at least no small nozzle! Max temp, max air... but before, remove board from device, it is actively cooling down from bottom side.
                            Last edited by harp; 11-08-2023, 09:22 AM.

                            Comment

                            • CapLeaker
                              Leaking Member
                              • Dec 2014
                              • 8126
                              • Canada

                              #15
                              Re: UV LED Device Repair

                              Should have used low melt solder first, then preheat then take it off with an 80W soldering iron with a wide tip.
                              Max air and max heat on the reflow station just burns stuff… at least mine does.

                              Comment

                              • dennis_elx33
                                Member
                                • May 2019
                                • 32
                                • Malaysia

                                #16
                                Happy New Year everyone!! Please be informed that I was able to remove the unknown chip by using a pre-heater and wait for the PCB to heat up until around 150C. But the weird thing is, up until now, I'm still confused as to what part is this. Though I highly suspect it is a diode because it can light up the LED when ever i probe on the forward bias (possibly) and LED wont light up when reversed. The odd thing is that I could not see any voltage drop on both forward and reversed bias. The only indicator i can say is lighted LED. Need your expert advise on how can i test or prove what component is the SMD chip is. Thank you so much! -- This idea is credited to Harp and all of you guys who gave their inputs!!
                                Last edited by dennis_elx33; 01-18-2024, 02:03 AM.

                                Comment

                                Related Topics

                                Collapse

                                • hobostove
                                  Corsair RM1000e - Help identify 5VSB Zener diode
                                  by hobostove
                                  Hey there guys. I've got a Corsair power supply that's come across my bench dead. I usually don't mess with power supplies, but it's a slow week so I'm giving it a whirl.

                                  Taking it apart I heard a screw rattling around inside, and when I got it apart I found a couple blown components near what I think is the 5VSB area.

                                  There's a 22ohm resistor that's melted and open, but it still has the bands.

                                  The other part is a zener diode and it's top went to jesus, so I can't read the marking.

                                  It looks like the diode connects the source and drain of a TNY284...
                                  03-27-2025, 02:25 PM
                                • dj8452000
                                  How To Test a P-channel Trench Mosfet Using A Multimeter In Diode Mode
                                  by dj8452000
                                  I am new to electronics and I'm understanding most of what I'm reading but I have a mosfet on my board that I've identified as a P-channel Trench Mosfet. I haven't a clue how to test this and what I should expect to see with the multimeter probes. I am hoping someone with years more experience than myself can help me understand how to use a multimeter to read this. Please look at the drawing I have attached to this and can you try to explain to me what I should be doing with my multimeter in diode mode and what results I should expect from a good mosfet?...
                                  02-18-2025, 08:28 AM
                                • jezzaaaa
                                  Identify replacement diode
                                  by jezzaaaa
                                  I'm trying to find a replacement diode for one that has gone short.

                                  I have a generic USB charger that went short circuit to ground on 5V. I found that one of a pair of identical diodes in parallel (and in series with transformer secondary winding) has gone short in both directions, so I suspect it's bad. The marking is CSRS1045, which I believe is a low barrier Schottky with max current 10A and max reverse 45V. I found a spec sheet for CSRS1045-A that has same specs and also says 350mV drop when forward biased.

                                  I can't find the exact part number for sale. Similar...
                                  05-09-2023, 11:26 PM
                                • ktmmotocross
                                  laptop onboard memory test and identify bad chip
                                  by ktmmotocross
                                  Hello.
                                  Know somebody how to successfuly test bad onboard memory and maybe even bad chip localization?

                                  Have newer asus that show memory related BSOD. After reball still the same. how to test if it is some ram chip or maybe bad ball under cpu or even cpu
                                  07-16-2024, 05:33 AM
                                • gurj1979
                                  Ubiquitiu 24 port POE. Help Identify Diode 3pin)
                                  by gurj1979
                                  Hi again guys.
                                  Ive got a Ubiquiti 24 port POE Switch which has failed to work. Fans turn on, but no lights.
                                  I've ripped the board out, flipped it upside down and noticed a blown 3pin SMD Diode (at location D53). Marking is ESSP (as with all the other Diodes in the same row).

                                  Anyone help me identify the model of this Diode ?...
                                  08-23-2023, 08:39 AM
                                • Loading...
                                • No more items.
                                Working...