Questions for Fusible Resistors

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  • cbr600rr_blue
    Member
    • Apr 2014
    • 14
    • Malaysia

    #1

    Questions for Fusible Resistors

    Hope that experts can share their views here

    I have a blown fusible resistor labeled as W1/2J 2.2 ohm FU985. I interpreted it as 0.5 Watt, +/-5% tolerance. I can't read out further information. The dimension of this blown fusible resistor is 10mm in length and 5mm in diameter as the attached photo. It is relatively big.

    When I tried to order this online, tyco FRN50 seems to have same specification. But the dimension of FRN50 is much smaller.

    It is 6.3mm in length 2.3mm in diameter.

    It is only about half of the size of the blown one. Will this replacement work?

    I have attached the specification for FRN50. Does size matter especially the heat and thermal concerns?
    Attached Files
  • cbr600rr_blue
    Member
    • Apr 2014
    • 14
    • Malaysia

    #2
    Re: Questions for Fusible Resistors

    Hi,
    no one can share the knowledge?

    Comment

    • budm
      Badcaps Legend
      • Feb 2010
      • 40746
      • USA

      #3
      Re: Questions for Fusible Resistors

      If you look at the spec, the withstand voltage after fusing (after blown open) is one of the important number to compare to the old one. It is similar to the fuse voltage rating, I.E. you do want to 5A 32V car fuse to replace the 5A 250V fuse used in the line operate equipment.
      Do you know where this fusible resistor is used in the circuit and how high is the voltage it is being used in?
      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

      • Longbow
        Badcaps Veteran
        • Jun 2011
        • 623
        • USA

        #4
        Re: Questions for Fusible Resistors

        Application? A fusible resistor is not a fuse, it is a resistor that is usually made of fireproof material, and designed to smoke at a certain current level. The wattage of the resistor will determine if the resistor smokes or just gets warm. Even if you can't find a reference for those numbers, look at your circuit to see what is required.
        Is it plugged in?

        Comment

        • budm
          Badcaps Legend
          • Feb 2010
          • 40746
          • USA

          #5
          Re: Questions for Fusible Resistors

          There is FLAME PROOF resistor, and then there is FUSIBLE resistor/FLAMEPROOF fusible resistor that serves 3 functions.


          http://www.interfacebus.com/Electron...r-terms-F.html

          When it goes open, it must not allow the voltage to jump over the open circuit, thus the the withstand voltage after fusing rating is provided.
          FRN series is the Flame proof Fusible resistor.

          EMC and ULW are aimed chiefly at mains input protection for
          small power supplies and battery chargers. Here it performs
          three circuit protection functions:

          1. Providing protection against supply line voltage transients,
          often in conjunction with a shunt element such as a Varistor
          or Transient Voltage Suppressor (TVS). This enables the
          designer to achieve the required level of immunity to
          conducted lightning induced surges.

          2. Restricting the peak inrush current at switch-on to levels
          suitable for the rectifier bridge and consistent with good
          EMC design.

          3. Preventing fire by fusing safely under fault conditions such
          as rectifier or capacitor breakdown.
          Attached Files
          Last edited by budm; 04-10-2014, 10:23 AM.
          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

          • cbr600rr_blue
            Member
            • Apr 2014
            • 14
            • Malaysia

            #6
            Re: Questions for Fusible Resistors

            Hi,
            This is for Sharp AQUOS LCD TV power supply board DPS-226-AP-1. It's at primary circuit so it must be 230volts AC.

            So can this replacement fusible resistor FRN50 be used but with a much smaller dimension?

            Comment

            • redwire
              Badcaps Legend
              • Dec 2010
              • 3906
              • Canada

              #7
              Re: Questions for Fusible Resistors

              Size of a resistor and it's temperature rating determine the wattage. That resistor is the size of a 2W part.
              I would not use the 1/2 part as a replacement.
              Most power resistors are rated at 70°C, so their size determines the wattage.

              Yageo Flame-Proof type_RSF.pdf

              Comment

              • cbr600rr_blue
                Member
                • Apr 2014
                • 14
                • Malaysia

                #8
                Re: Questions for Fusible Resistors

                Hi
                I thought that W1/2J is 1/2Watt (0.5Watt) because J is tolerance.

                Originally posted by budm
                If you look at the spec, the withstand voltage after fusing (after blown open) is one of the important number to compare to the old one. It is similar to the fuse voltage rating, I.E. you do want to 5A 32V car fuse to replace the 5A 250V fuse used in the line operate equipment.
                Do you know where this fusible resistor is used in the circuit and how high is the voltage it is being used in?
                Last edited by cbr600rr_blue; 04-10-2014, 06:03 PM.

                Comment

                • cbr600rr_blue
                  Member
                  • Apr 2014
                  • 14
                  • Malaysia

                  #9
                  Re: Questions for Fusible Resistors

                  This is the photo for the blown fuse before desoldered.

                  Originally posted by budm
                  If you look at the spec, the withstand voltage after fusing (after blown open) is one of the important number to compare to the old one. It is similar to the fuse voltage rating, I.E. you do want to 5A 32V car fuse to replace the 5A 250V fuse used in the line operate equipment.
                  Do you know where this fusible resistor is used in the circuit and how high is the voltage it is being used in?
                  Attached Files

                  Comment

                  • budm
                    Badcaps Legend
                    • Feb 2010
                    • 40746
                    • USA

                    #10
                    Re: Questions for Fusible Resistors

                    More likely to be for main B+ line which will be around 330VDC. Trace out the circuit to see if one end is connected to the + terminal of the main filter cap (450VDC rating). There must be shorted out components that you need to checked out.
                    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

                    • cbr600rr_blue
                      Member
                      • Apr 2014
                      • 14
                      • Malaysia

                      #11
                      Re: Questions for Fusible Resistors

                      Hi,
                      Actually this is related to another post few days ago where a TNY264PN IC crack. At that time, U only replace the IC but didn't know that this fusible resistor also blown.
                      see the link:
                      https://www.badcaps.net/forum/showth...264#post436087

                      Originally posted by budm
                      More likely to be for main B+ line which will be around 330VDC. Trace out the circuit to see if one end is connected to the + terminal of the main filter cap (450VDC rating). There must be shorted out components that you need to checked out.

                      Comment

                      • budm
                        Badcaps Legend
                        • Feb 2010
                        • 40746
                        • USA

                        #12
                        Re: Questions for Fusible Resistors

                        So it is the fusible resistor for feeding the B+ which is around 330VDC. So the fusing withstand voltage should b e more than 330v
                        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

                        • redwire
                          Badcaps Legend
                          • Dec 2010
                          • 3906
                          • Canada

                          #13
                          Re: Questions for Fusible Resistors

                          Looks like it is made by Futaba. They have some funny names for their resistors: "ANTI-BURST FUSIBLE RESISTOR", "HEAT ENERGY SURGE WIRE WOUND FUSIBLE RESISTOR" etc. Take a look under "fusible" category.
                          Note a fusible resistor has two voltage ratings - the max. working voltage, and the max. fuse voltage. This is a 2.2R beast, so it would normally never seen more than a few volts.
                          Why it is so big and really a 1/2W? I guess its a high-voltage type, or non-inductive if used as a snubber.
                          Last edited by redwire; 04-10-2014, 08:07 PM. Reason: wrong url

                          Comment

                          • budm
                            Badcaps Legend
                            • Feb 2010
                            • 40746
                            • USA

                            #14
                            Re: Questions for Fusible Resistors

                            https://www.badcaps.net/forum/showth...264#post436087

                            Lets stick to one thread.
                            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

                            • cbr600rr_blue
                              Member
                              • Apr 2014
                              • 14
                              • Malaysia

                              #15
                              Re: Questions for Fusible Resistors

                              Originally posted by budm
                              Hi,

                              Followed by the replacement of 2.2 ohm fusible resistor, the LCD TV powers up nicely now.
                              Thanks everyone help.

                              Comment

                              • cbr600rr_blue
                                Member
                                • Apr 2014
                                • 14
                                • Malaysia

                                #16
                                Re: Questions for Fusible Resistors

                                Hi,
                                You are great! The FU is FUTABA.
                                It's Taiwanese maker.
                                It's antiburst no wonder the size is bigger than usual.
                                Other makes are usually flame-proof only

                                Originally posted by redwire
                                Looks like it is made by Futaba. They have some funny names for their resistors: "ANTI-BURST FUSIBLE RESISTOR", "HEAT ENERGY SURGE WIRE WOUND FUSIBLE RESISTOR" etc. Take a look under "fusible" category.
                                Note a fusible resistor has two voltage ratings - the max. working voltage, and the max. fuse voltage. This is a 2.2R beast, so it would normally never seen more than a few volts.
                                Why it is so big and really a 1/2W? I guess its a high-voltage type, or non-inductive if used as a snubber.

                                Comment

                                • steinless
                                  Member
                                  • Aug 2013
                                  • 37
                                  • singapore

                                  #17
                                  Re: Questions for Fusible Resistors

                                  Hey all would like to ask, if i replace it with a 4.7 ohm fusuable, would it affect anything?

                                  Comment

                                  • SteveNielsen
                                    Retired Tech
                                    • Jun 2012
                                    • 2327
                                    • USA

                                    #18
                                    Re: Questions for Fusible Resistors

                                    You should always replace a fusible resistor with the same value.

                                    Comment

                                    • jeremykum
                                      Senior Member
                                      • Feb 2012
                                      • 95
                                      • Malaysia

                                      #19
                                      Re: Questions for Fusible Resistors

                                      Just wish to say thank you for the people sharing here.
                                      Now trying to fix a Sharp DSP-174AP board from 40", owner claims lightning strike.

                                      Initially located a Toshiba K3256 N channel FET shorted. Circuit not shorted. Replace it but still not powering up.

                                      Now notice this W1/2J 2.2 ohm should be dead. This board have 2 pcs of these at the main cap 320V. The R7910 input 320V, while output only 1.5V. Will try to order and replace it.
                                      Attached Files
                                      Mainly repair laptops, sometimes LCD/LED monitors. Also accepts changing/reballing/reflow BGA job request.

                                      Comment

                                      • nickgronk
                                        Member
                                        • Apr 2021
                                        • 32
                                        • Canada

                                        #20
                                        Re: Questions for Fusible Resistors

                                        Does anyone know of a suitable replacement for this resistor. I am having a hard time finding a good replacement.

                                        Comment

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