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    Help substituting avalanche diode

    repairs on an old CRT tv from the 80s that blew a flyback have led me to this diode which is reading near 0 in both directions. The diode is marked as an R2KY avalanche diode but is no longer manufactured.

    I am fairly new to the world of electronics, could anyone help me source a suitable modern-day equivalent diode?


    The datasheet of the diode can be found from
    https://datasheetspdf.com/pdf/220430...ctorInc/R2KY/1

    many thanks : )

    #2
    Re: Help substituting avalanche diode

    do you have a schematic to show where it was used?

    Comment


      #3
      Re: Help substituting avalanche diode

      You can get one from here: https://www.ebay.co.uk/itm/R2KY-ZENE...-/192164981448

      Comment


        #4
        Re: Help substituting avalanche diode

        NIKKO??? good luck.
        that guy is down the road - he is hardly open and often exagerates stock.
        but you may get lucky.

        Comment


          #5
          Re: Help substituting avalanche diode

          Originally posted by stj View Post
          do you have a schematic to show where it was used?
          unfortunately not. The tv is a Mitsubishi ct 2043B although it seems to be really obscure.


          The diode is connected to a voltage regulator. I will have a look at making a schematic in the next few days : )

          Comment


            #6
            Re: Help substituting avalanche diode

            Originally posted by R_J View Post
            Thanks, although I am a little worried that he states the part is 160v 1a as I'm sure the part should be 120v 2A?

            I may give it a go though.

            Comment


              #7
              Re: Help substituting avalanche diode

              Originally posted by Bibdid View Post
              unfortunately not. The tv is a Mitsubishi ct 2043B although it seems to be really obscure.


              The diode is connected to a voltage regulator. I will have a look at making a schematic in the next few days : )
              what is the board number ? will be something like vestel------- or maybe Haier -----
              there is a schematic but asks to sign up . http://freebodydiagram.archivioprimo...our-television
              Last edited by petehall347; 02-20-2021, 06:27 PM.

              Comment


                #8
                Re: Help substituting avalanche diode

                I believe it is just for over voltage protection on the +112 volt line to the horz. output section. I would replace the low voltage/capacity electrolytics in the primary, If they are bad the power supply might not regulate properly, it could also be bad caps on that B+ 112v line, If the caps go open the voltage can go up. You should be able to use the NTE570
                Check the schematic for the CT-2153
                Last edited by R_J; 02-20-2021, 07:05 PM.

                Comment


                  #9
                  Re: Help substituting avalanche diode

                  Originally posted by petehall347 View Post
                  what is the board number ? will be something like vestel------- or maybe Haier -----
                  there is a schematic but asks to sign up . http://freebodydiagram.archivioprimo...our-television
                  That looks promising but the site seems to be very shady. Relinks me to scam sites.

                  I have attached some board model/serial numbers although it seems very obscure.
                  Attached Files

                  Comment


                    #10
                    Re: Help substituting avalanche diode

                    Originally posted by R_J View Post
                    I believe it is just for over voltage protection on the +112 volt line to the horz. output section. I would replace the low voltage/capacity electrolytics in the primary, If they are bad the power supply might not regulate properly, it could also be bad caps on that B+ 112v line, If the caps go open the voltage can go up. You should be able to use the NTE570
                    Check the schematic for the CT-2153
                    Thanks for the help. I measured the capacitance and esr of a few capacitors around that area and they are way out of spec. Is it possible that these caps took out the flyback? I know this tv has had a very hard life and the flyback exploded somewhat violently, with resin being thrown out a fair distance onto the board.

                    As for the schematic, is there any reason you recommend the CT-2153 over others, just out of curiosity?

                    Comment


                      #11
                      Re: Help substituting avalanche diode

                      . cant make sense out of the board numbers yet .. maybe there are more numbers or a sticker
                      Last edited by petehall347; 02-25-2021, 08:50 AM.

                      Comment


                        #12
                        Re: Help substituting avalanche diode

                        this looks like it ...

                        Comment


                          #13
                          Re: Help substituting avalanche diode

                          It is possible that the power supply started to output a higher voltage causing the flyback to operate at a higher voltage and break down, but it could be the flyback was just at its end of life. I picked that schematic because I could not find the actual one for your tv so I found a Mitsubishi tv that had a similar circuit.
                          The Hitachi chassis is totally different
                          Last edited by R_J; 02-25-2021, 12:10 PM.

                          Comment


                            #14
                            Re: Help substituting avalanche diode

                            not hard to find.
                            it's D907
                            Attached Files

                            Comment


                              #15
                              Re: Help substituting avalanche diode

                              I would use P5KE120A TVS diode as a replacement.

                              Comment


                                #16
                                Re: Help substituting avalanche diode

                                Is there anything special about this type diode
                                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


                                  #17
                                  Re: Help substituting avalanche diode

                                  It's got a misleading name "avalanche diode" and nominal 120V (130-155V) rating. So it's a zener (=avalanche mode) but the wide range of reverse voltage spec. and high surge capability 2A 100usec mean it's really a TVS diode.

                                  In the TV circuit, I can't find the schematic again but it seems to be an overvoltage clamp for when the power supply puts out too much voltage.
                                  If the STR fails or something else happens the rail can go too high and the TVS diode clams to protect something but it will cook and short if that stays true for a long time. I see main power like 115VDC go up too high due to a bad regulator and it damages other parts, flyback too if the x-ray protection does not trip.

                                  Comment

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