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    Is it a transistor or a mosfet?

    Hello all again and good day....I need some advice from the attach drawing, can someone please tell me if Q130 is a transistor or mosfet? If so, what pin is pin1,2,3? Hoping for your continual support....thanks

    Click image for larger version. 

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    Re: Is it a transistor or a mosfet?

    Hi,

    This is not a true schematic.
    And additionally the function is not obvious.

    I recommend to read the documentation to the "schematic" or contact the author.

    ****
    All in all this does not look very professionally, I'd not rely on such "bad" informations.

    Klaus
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    Re: Is it a transistor or a mosfet?

    My apology that I wasn't able to mentioned early....I dont have schematic diagram ... I did trace and sketch the drawing myself...I can do more sketching if the drawing is not complete to conclude....thanks



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    Re: Is it a transistor or a mosfet?

    Hi,

    From post#2:
    And additionally the function is not obvious.
    Is the expected function so secret that you can't explain?

    Klaus
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    Re: Is it a transistor or a mosfet?

    Quote Originally Posted by KlausST View Post
    Hi,

    From post#2:

    Is the expected function so secret that you can't explain?

    Klaus
    It acts like electronic switch that turns on/off the bulb. It's either mosfet or transistor. Need more opinions from experts...thanks in advance.



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    Re: Is it a transistor or a mosfet?

    I would be inclined to think that this is an overvoltage
    warning light and if true, then I would pick a PNP BJT
    for the function with emitter to the LT1057, base to
    the resistor/zener/resistor and collector to the DG408 /
    bulb leg. Then when emitter goes above base by 0.7V
    you light the bulb, and the zener can be picked for a
    roughly-right fault threshold.

    Why the DG408 is there at all, is a mystery (maybe a
    secondary defeat / enable to the crude comparison).



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    Re: Is it a transistor or a mosfet?

    Quote Originally Posted by dick_freebird View Post
    I would be inclined to think that this is an overvoltage
    warning light and if true, then I would pick a PNP BJT
    for the function with emitter to the LT1057, base to
    the resistor/zener/resistor and collector to the DG408 /
    bulb leg. Then when emitter goes above base by 0.7V
    you light the bulb, and the zener can be picked for a
    roughly-right fault threshold.

    Why the DG408 is there at all, is a mystery (maybe a
    secondary defeat / enable to the crude comparison).

    The original part actual is shown in the image below. I found it shorted (pin2 & pin3). The problem is I couldn't find that component online. Even datasheet is hard to find. Thus I am now having trouble replacing this part the reason I brought it up here. Hoping someone can help me figure out suitable replacement to repair the board. Thanks.

    Click image for larger version. 

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    Re: Is it a transistor or a mosfet?

    Hi,

    You have a PCB, maybe from a known device with known vendor and article name...with parts assembled, with part numbers printed on it...
    You hide a lot of informations but want us to solve the riddle of post#1.

    Klaus
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    Re: Is it a transistor or a mosfet?

    Really shorted or low resistance? Could be a JFET and not defective.



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    Re: Is it a transistor or a mosfet?

    see this thread

    https://www.edaboard.com/showthread....p;goto=newpost

    i200yrs started it on July 14 2019


    1 members found this post helpful.

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    Re: Is it a transistor or a mosfet?

    Quote Originally Posted by FvM View Post
    Really shorted or low resistance? Could be a JFET and not defective.
    I tried removed and discharged all pins by shorting it...But the low-ohm still remain about 10 ohms. And i believe it can't be middle pin and 3rd pin got low ohm in TO-92 right?
    Last edited by i200yrs; 7th November 2019 at 03:15.



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    Re: Is it a transistor or a mosfet?

    There are many annoying points with this thread
    - cross posting an old question without at least referring to the previous thread
    - not giving appropriate information, e.g. the TO92 photo, from the start. Your pin numbers are confused, unfortunately.

    The pin assignment matches popular PJFETs like J174, it could be a lower ohmic switch JFET variant. Can be easily verified by identifying the gate diode junction and switch opening with reversed gate bias. You would first check for P or N polarity.

    That's still a guess, but your considerations are incomplete without checking the most obvious explanation.


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    Re: Is it a transistor or a mosfet?

    Quote Originally Posted by FvM View Post
    There are many annoying points with this thread
    - cross posting an old question without at least referring to the previous thread
    - not giving appropriate information, e.g. the TO92 photo, from the start. Your pin numbers are confused, unfortunately.

    The pin assignment matches popular PJFETs like J174, it could be a lower ohmic switch JFET variant. Can be easily verified by identifying the gate diode junction and switch opening with reversed gate bias. You would first check for P or N polarity.

    That's still a guess, but your considerations are incomplete without checking the most obvious explanation.
    Really my apology FvM...sorry you guys confused my information and some incomplete...Do you want me to trace more or any data you requires please enumerate to me and i try my best to provide...thanks

    On the other hand, do you agree that JFET 3 pins should be open to each other after discharge (discharge means by shorting all pins)? Because the original component maintain low-ohm (10ohms) even after discharged...thanks again.

    - - - Updated - - -

    Quote Originally Posted by wwfeldman View Post
    see this thread

    https://www.edaboard.com/showthread....p;goto=newpost

    i200yrs started it on July 14 2019
    Thanks for reminder...I made the problem worst after replacing with TN0604N3...which means my replacement is not correct...The reason i brought it up again...thanks a lot
    Last edited by i200yrs; 7th November 2019 at 09:14.



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    Re: Is it a transistor or a mosfet?

    On the other hand, do you agree that JFET 3 pins should be open to each other after discharge (discharge means by shorting all pins)? Because the original component maintain low-ohm (10ohms) even after discharged
    No, JFET is depletion mode FET, low resistance ("on") with zero gate voltage and off with reversed gate bias, positive voltage for PFET and negative voltage for NFET.



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    Re: Is it a transistor or a mosfet?

    Hope that you have a DMM

    Start with the information on the following page:

    https://engineeringtutorial.com/test...al-multimeter/

    There are other web pages showing how to test Mosfets, JFets, etc.

    Or invest in something like this. This is only an example, there are MANY similar testers on Amazon, Ebay, Alibaba, etc. I have one, and it has been a real time-saver to identify unknown components.

    https://www.ebay.com/sch/i.html?_fro...&_sacat=181939
    My batteries are recharged by "Helpful Post" ratings.
    If you feel that I've helped you, please indicate it as a Helpful Post



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    Re: Is it a transistor or a mosfet?

    Quote Originally Posted by FvM View Post
    No, JFET is depletion mode FET, low resistance ("on") with zero gate voltage and off with reversed gate bias, positive voltage for PFET and negative voltage for NFET.
    Thanks for the inputs...but the low-ohm pins are the middle pin and the 3rd pin...Which based from JFET TO-92 pin configuration the pins are Source and Gate...So it should not read low-ohm, right? thanks



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    Re: Is it a transistor or a mosfet?

    There are FETs with different pin mapping available. Follow the suggestions in post #15 and consider all measurement information.



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    Re: Is it a transistor or a mosfet?

    Quote Originally Posted by FvM View Post
    There are FETs with different pin mapping available. Follow the suggestions in post #15 and consider all measurement information.
    Ok FvM...I will google more about the pin configuration...And yes i believe you're right...This part is misdiagnosed. The problem is, I disposed the part already into scrap bin and thrown away....can't get it back again. Can you or anyone can suggest a replacement please ?



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