looking for diode

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  • rhomanski
    nowhere man
    • Dec 2009
    • 5157
    • U S of A

    #1

    looking for diode

    I need to replace some xz051 zener diodes. The online datasheets were confusing, I swear one didn't have a period. I've never heard of a 51v zener. I was thinking a 1n4733 might be a good replacement. Anybody got a manual of replacements?
    sigpicThe Sky Is Falling
  • Agent24
    I see dead caps
    • Oct 2007
    • 4951
    • New Zealand

    #2
    Re: looking for diode

    The diode is used in https://archive.org/details/icom_IC-R70_serv which is D3\D4 in the power supply\regulator. (last page, bottom right of PDF).

    The rail they're on for a voltage reference to the regulator has a 16v electrolytic on it, so I doubt they are regulating it to 102 volts!
    If you saw 51 volts anywhere in a datasheet it must have been a typo.

    I see no reason why a 1N4733 shouldn't work with whatever you're doing.
    Attached Files
    Last edited by Agent24; 02-27-2016, 06:58 PM.
    "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
    -David VanHorn

    Comment

    • rhomanski
      nowhere man
      • Dec 2009
      • 5157
      • U S of A

      #3
      Re: looking for diode

      I thought it would, nice to have a second opinion though. Thanks.
      sigpicThe Sky Is Falling

      Comment

      • redwire
        Badcaps Legend
        • Dec 2010
        • 3907
        • Canada

        #4
        Re: looking for diode

        I did the math and they (D3, D4) are both 5.1V zeners, in series as the voltage reference for the 13.8VDC regulator.
        1N4733A's would be fine. R2 is the start-up resistor, check it is not burnt/open if the regulator has no output.
        Attached Files

        Comment

        • Agent24
          I see dead caps
          • Oct 2007
          • 4951
          • New Zealand

          #5
          Re: looking for diode

          Originally posted by redwire
          I did the math and they (D3, D4) are both 5.1V zeners, in series as the voltage reference for the 13.8VDC regulator.
          1N4733A's would be fine. R2 is the start-up resistor, check it is not burnt/open if the regulator has no output.
          Just to point out, I have no idea if rhomanski is repairing an IC-R70... it was just the first place I found XZ051 diodes used, and where it would be obvious if they were 5.1 or 51 volt.
          "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
          -David VanHorn

          Comment

          • fzabkar
            Badcaps Veteran
            • Mar 2009
            • 772
            • Australia

            #6
            Re: looking for diode

            NTE's cross reference suggests that the XZ051 crosses to NTE135A which is a 5.1V 1W zener.

            http://nte01.nteinc.com/nte%5CNTExRefSemiProd.nsf/$all/BBFB03A671FA6524852579A4000C9AE6?OpenDocument
            https://cdn.badcaps-static.com/pdfs/...69713cd2db.pdf

            Comment

            • rhomanski
              nowhere man
              • Dec 2009
              • 5157
              • U S of A

              #7
              Re: looking for diode

              Thanks fzabkar, but I try not to use NTE. It's actually for an old direct drive turntable. It has two secondary's on the transformer one zener is used to clamp the output to 5 volts for one secondary another is used in a feedback loop to clamp the output to 20 volts for the other secondary. Since it was designed for 120v input and the line has been raised to 124v since then, I think the zeners will be worked harder than they were meant to be. I found the schematic since the first post.

              A few are sprinkled around for basically the same duty in critical points. The five volt line feeds the IC directly. The schematic shows a triangle with 8 numbers and seven lines, one number is not used. On the board the IC is in a metal can like an early transistor only with eight legs instead of three. I doubt if a zener went bad I could ever find a replacement for the IC. I've been trying to work up a modern parts list to rebuild the unit. I have 3 of these tables and one set of guts as a spare. So I have some work to do. I've already rebuilt the other pieces of the system. The tuner was the worst so far. So many obsolete parts to find.

              Thanks for the help everybody. Your a swell bunch of guys and gals.
              Last edited by rhomanski; 02-28-2016, 12:09 AM.
              sigpicThe Sky Is Falling

              Comment

              • Agent24
                I see dead caps
                • Oct 2007
                • 4951
                • New Zealand

                #8
                Re: looking for diode

                Originally posted by rhomanski
                Thanks fzabkar, but I try not to use NTE.
                Any particular reason? I just ordered some transistors from them - hopefully not a bad move!

                Originally posted by rhomanski
                The schematic shows a triangle with 8 numbers and seven lines, one number is not used. On the board the IC is in a metal can like an early transistor only with eight legs instead of three. I doubt if a zener went bad I could ever find a replacement for the IC.
                What's the part number? With 8 pins and a triangle symbol it might just be an early production op-amp, or something else common.
                "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                -David VanHorn

                Comment

                • fzabkar
                  Badcaps Veteran
                  • Mar 2009
                  • 772
                  • Australia

                  #9
                  Re: looking for diode

                  Originally posted by Agent24
                  What's the part number? With 8 pins and a triangle symbol it might just be an early production op-amp, or something else common.
                  That's what I thought, too. I've seen plenty of these in my time. I probably still have some.

                  Comment

                  • rhomanski
                    nowhere man
                    • Dec 2009
                    • 5157
                    • U S of A

                    #10
                    Re: looking for diode

                    Well, for the NTE thing, they don't make anything. They buy the cheapest part that meets the specification. You could be getting anything. I'm a typical middle class consumer, Bounty paper towels, genuine GM parts for the car. I've used NTE before and had no problem but, there's always a but, if you shop at walmart. I try to use Fairchild semi's much better quality control.

                    The semi is an op-amp and is listed as a upc255a. You got me curious and I googled it. Pacific semiconductors say they have 22 of them at 63 cents each. Wow, the unit is from the mid seventies when I graduated high school. My 40th anniversary is this year. I also found a page with cross reference. Maybe I should stock a few for emergencies.
                    sigpicThe Sky Is Falling

                    Comment

                    • Agent24
                      I see dead caps
                      • Oct 2007
                      • 4951
                      • New Zealand

                      #11
                      Re: looking for diode

                      Originally posted by rhomanski
                      Well, for the NTE thing, they don't make anything. They buy the cheapest part that meets the specification. You could be getting anything. I'm a typical middle class consumer, Bounty paper towels, genuine GM parts for the car. I've used NTE before and had no problem but, there's always a but, if you shop at walmart. I try to use Fairchild semi's much better quality control.
                      Now you scared me. I Googled NTE transistors and have come up with a bunch of people posting that NTE just relabel any old transistor that falls somewhere in the specification and sell it with a big markup.
                      I was under the impression they actually manufactured replacement parts that others had discontinued, hence the big price.
                      Maybe I should cancel my order...

                      Originally posted by rhomanski
                      The semi is an op-amp and is listed as a upc255a. You got me curious and I googled it. Pacific semiconductors say they have 22 of them at 63 cents each. Wow, the unit is from the mid seventies when I graduated high school. My 40th anniversary is this year. I also found a page with cross reference. Maybe I should stock a few for emergencies.
                      NTE sells them as NTE909
                      "Tantalum for the brave, Solid Aluminium for the wise, Wet Electrolytic for the adventurous"
                      -David VanHorn

                      Comment

                      • rhomanski
                        nowhere man
                        • Dec 2009
                        • 5157
                        • U S of A

                        #12
                        Re: looking for diode

                        Thanks! Lol.
                        sigpicThe Sky Is Falling

                        Comment

                        • redwire
                          Badcaps Legend
                          • Dec 2010
                          • 3907
                          • Canada

                          #13
                          Re: looking for diode

                          Late post, but the NTE909 is originally an LM709 op-amp. Pretty old, from the days of gold leads and metal cans.

                          I found NTE parts are good quality but quite expensive because they are private-labeling mainstream parts and providing the cross-reference service.

                          Comment

                          • budm
                            Badcaps Legend
                            • Feb 2010
                            • 40746
                            • USA

                            #14
                            Re: looking for diode

                            I used to use ECG for repairing Japanese audio and TV in the early 70s when the original Japanese parts were hard to come by those days unless you get them from the OEM and they were expensive.
                            ECG was then acquired by NTE.
                            Young people have it made these days, so much easier for them to get parts and service info on line.
                            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

                            • rhomanski
                              nowhere man
                              • Dec 2009
                              • 5157
                              • U S of A

                              #15
                              Re: looking for diode

                              Since I worked on commercial electronics, and systems not board level, parts wasn't much of a problem. We had manuals or microfiche and others got the parts for us. But I can see how much of a pain it would have been. The few projects I worked on for myself, TV's, radio's and the like it was hard to find some parts. I threw away a philco many years ago because I couldn't find a tube. It was discontinued in 1962 and all the manuals said there was no substitute. I tried for four years and finally found one in a garage sale for $1. Put it in and it had lost it's vacuum. I had sound for thirty seconds then silence. So disappointing.
                              sigpicThe Sky Is Falling

                              Comment

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