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Case styles and mystery component

Discussion in 'Electronic Basics' started by Randy Day, Feb 8, 2007.

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  1. Randy Day

    Randy Day Guest

    1) is there a resource on the 'net that has
    diagrams of the various semiconductor case types?
    I mean like the old TO-series stuff, to the new
    SMT cases. I'm trying to ID an old part I found,
    and I don't even know what the case designator is
    (see 2).

    2) It's an all-metal case, threaded at one end, a
    knurled metal midsection, and two lug-type
    connectors at the other end.
    The lettering reads "DPC209 RCA 8432"

    0 o
    | |
    | |

    The one reference I could find thought it might
    be an SCR, but said nothing more about it.
  2. Rich Grise

    Rich Grise Guest

    How big is this thing? The numbers are probably house numbers,
    but the "RCA" kinda rings a bell. ;-) The stud is supposed to
    bolt to a heat sink, and the other two things are either the
    emitter and base of a power transistor, or the cathode and gate
    of an SCR, or MT2 and gate of a triac, in which case the case
    would be MT1.

    Do you know how to ohm out a transistor? Put your ohmmeter in
    "diode test" mode, and a transistor will look like two diodes,
    back-to-back. The polarity of the measurements will tell you
    if it's PNP or NPN, and the forward drop will tell you if it's
    silicon or germanium. Yes, this package is so old that it might
    actually be a germanium power transistor.

    But, if your reference says "SCR", then I'd test that theory.
    Set up a little circuit with a power supply of a few volts,
    say 3 or 6 or whatever. Put some kind of load from the stud
    (which we're guessing is the anode) to the positive end of
    the supply. Come to think of it, a flashlight bulb would be
    ideal - just match the supply voltage! :)

    The cathode will be the heavier lug - just connect that to the
    negative supply.

    Set that up, and take maybe a 100K resistor and touch it to both
    the anode (the case) and the gate (the smaller of the two tabs)
    and if it's an SCR, the light bulb will come on and stay on.

    If it's an NPN transistor, the light will come on weakly, depending
    on the value of the resistor that you've got from what turns out
    to be the collector to what's evidently the base.

    Well, you get the idea.

    Have Fun!
  3. Ross Herbert

    Ross Herbert Guest

    I would opine that the "8432" is the date code which makes it unlikely
    to be a germanium device. I also strongly suspect it will be an SCR.
    If this is the case, the stud is Anode, the longer terminal is Cathode
    and shorter terminal is Gate.
    Depending on gate sensitivity 100K may be too high. 1K is fine for
    higher power SCR's.
  4. Eeyore

    Eeyore Guest

    Thyristor is very likely. You can find them with google but haven't found a
    description yet.

  5. jasen

    jasen Guest

    8432 looks like a date code,
    RCA could be the manufacturer
    that'd make DPC209 the part number.

    K G
    I've also seen triacs in that case.

  6. Chris

    Chris Guest

    Hi, Mr. Day. In days of yore, the package you're describing ruled the
    earth. It was called "press-fit", and was the standard package for
    power thyristors like triacs and SCRs. The idea was, you'd drill a
    hole of standard diameter into the aluminum heat sink (which was at
    least 1/4" thick), and then use an arbor press to press the package
    into the hole. The knurling on the sides would ensure a good thermal
    contact between the aluminum and the package itself. Note that the
    semiconductor die is actually on the inside bottom of the package can,
    so for this type of package, the heat has to travel internally from
    the bottom of the package to the sides to be dissipated externally.
    In short, lame for several reasons.

    Usually, the online database for IC and semiconductor packages is the
    manufacturer data sheets. If a mechanical drawing isn't on the
    datasheet, it will be referenced and available on the web.

    Unfortunately, the press fit stuff just isn't made any more. You'd
    have to rely on old data books or such. Your part is a "house
    number" (not a standard GE part number -- they used to label standard
    semis with the customer P/N instead of standard to "make" the customer
    buy replacemnts from the customer and not repair it themselves(?!?!).
    That makes it worse.

    If you can get a standard part number, I'd suggest going to the NTE
    site. The NTE cross-reference data sheet will tell you what the JEDEC
    package is called, and also provide a mechanical sketch.$$Search?OpenForm

    Good luck
  7. Eeyore

    Eeyore Guest

    Umm No !

    This one has the threaded stud.

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