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Transistors... help

Discussion in 'Troubleshooting and Repair' started by Ian Schmidt, Nov 28, 2016.

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  1. Ian Schmidt

    Ian Schmidt

    Nov 28, 2016
    IMG_0188.JPG So, I have two PNP transistors model MJ15004G. Trying to see if they are operational but this realm of electronics has me scratching my head. I have tried to research testing these but cannot find any useful guides to differentiate B,E, and C. I tested them with a model 87 Fluke DMM on diode setting and m-Ω. Attached picture shows results. Any expertise? Thanks in advance.
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    Jan 21, 2010
    You don't note the units on the ohm range. Your meter almost certainly autoranges.

    I would assume the values between pins 1 and 3 are in MΩ. The others are probably kΩ. OL means there is no detectable (by your meter) conductance between these pins. Be careful that you don't touch the metallic parts of the probes or your own body's resistance can affect the readings (I don't think that happened here).

    The diode check range is the most useful. You can typically distinguish the collector from the emitter by the lower forward voltage. In this case, both base to collector readings are lower than the base to emitter readings.

    All TO3 outline BJT transistors have the same lead arrangement. The case is connected to the collector. From that the other connections are obvious.

    There is also the datasheet which clearly tells you which connection is which on the first page.
  3. Ian Schmidt

    Ian Schmidt

    Nov 28, 2016
    Thanks for the quick reply. Sorry I forgot the values when I rewrote it but I was just trying to figure if the open and closed contact points would show if it was good or bad. That datasheet you linked was just what I have been searching for. Thank you
  4. 73's de Edd

    73's de Edd

    Aug 21, 2015
    Sir Ian Schmidt . . . . .

    Looks like two very good transistors with VF junction voltages of 498 mv and 485 mv on one set of junctions of one transistor and VF junction voltages of 498 mv and 483 mv on the set of junctions of the other transistor.
    Very closely matched . . . . .just like we can see when their dies are coming from the same mother wafer.

    73s de Edd
  5. elebish


    Aug 16, 2013
    Terminal 1 is Emitter. terminal 2 is Base and case is Collector. These are typical PNP silicon audio output T03 style transistors similar to an ECG 61.Collector voltage should be around 140 VDC max and Collector AMPS at 20 max. Wattage around 250 when properly heat sinked and frequency max is 2 MHZ. Forward voltage drop between emitter and base should be between .450 and .550 with multi meter in diode check mode.
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