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Zener Diode ID & Specs help needed.

Discussion in 'Datasheets, Manuals and Component Identification' started by dh390, Aug 2, 2013.

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  1. dh390


    Jul 30, 2013
    Hi all,
    I am new here but not new to electronics. I find myself needing help IDing this Zener Diode (see attached pics).

    The diode is from a '70s GM Delco AM/FM car radio. When I decoded the radio's service # it says it's a 1972 built unit.





    There are 3 #'s on this diode in an arrangement that I have not seen before. I have tried looking up the #'s several ways but no luck.

    Here are the #'s printed on the diode: 99 234 466 (see the pics for how they are printed on the diode).

    I think the voltage on this Zener is around 7.5 to 7.9v but I don't know for sure. This is based on the readings I got before the diode failed/shorted. I also don't know the wattage.

    Can someone please help with the specs on this zener diode?

    Also does someone maybe have a schematic & pc board layout for 1972 GM Delco AM/FM radio they could post?

    If more pics are needed of the diode or if pics of the radio are needed let me know.

    Thanks in advance.
    Last edited: Aug 2, 2013
  2. shrtrnd


    Jan 15, 2010
    We're not ignoring your question, we just don't know the answer.
    My experience with US car electronics manufacturers, is that Delco puts their own
    proprietary part numbers on their devices, supposedly so that only factory authorized
    service people will work on them.
    Hopefully somebody on here will have a definitive answer for you. Or a schematic of
    your radio.
    I don't know if it'd do any good, but you might try Googleing Delco part numbers for
    diodes, or your radio model number, and see if anything comes up.
    Good luck.
    p.s. If your zener blew, you've probably got other power supply problems you need to
    look at too.
  3. alfa88


    Dec 1, 2010
    The lazy man's answer: Mouser has a [email protected] Zener and it's pretty darned inexpensive
  4. dh390


    Jul 30, 2013
    Thanks guys, no problem. I have run into house marked parts in other things before & it is a pain to say the least. As for the power supply problem, it was me. I accidentaly shorted it out in my testing. :(

    I had already ordered a 7.5v zener to give it a try but have to wait till it arives to see if it will work.

    I have managed to find a Sams Photofact book from March of 1972. It doesn't have the exact model # but is darn close & the PC board layout is the same. From my understanding of the GM service #'s on the radios the one I am working on is a 3 revision or something along those lines. But the rest of the # matches. That revision could just be as simple as a different cast nose piece to fit the car it is for or the addition of a front rear fader (which this radio has).

    Anyway the Sams book is saying it is a DS-149 & crosses it to the following old #'s of GE-X11; Z1108; ECG 5072. Which comes up with a spec of 8.2v 1 Watt zener.

    But what is a little confusing & makes me question the 8.2v zener value a bit is the schematic showing a circuit voltage of 7.74v after the zener. With the bad zener removed I am getting about 9.5v to 10v (which I am not suprised).


    My question is with an 8.2v zener back in the attached circuit will the output voltage be the 7.74v the Sams book is showing?

    Thanks for the help.
    Last edited: Aug 8, 2013
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    Note that your original zener has a ferrite bead on one lead.

    It is probably a good idea to slip it off and to slip it on the same lead of the replacement.
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