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Transistor Codes?

Discussion in 'General Electronics Discussion' started by Yoa01, Oct 12, 2012.

  1. Yoa01

    Yoa01

    214
    0
    Jun 18, 2012
    Hi all,

    I was just curious, do transistors follow some kind of standardised coding system, like capacitors or resistors? I have a lot of them, all with different markings on them. I know they can vary by manufacturer, I just want to know if they follow any sort of actual code.

    Thanks!
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    Kinda yes, kinda no.

    The standard is that the manufacturer puts a code on the part that allows them to identify it. Usually they share this with you, and frequently it is the actual part number of the device.

    Each manufacturer has their own standard. Here is one.

    Size permitting you may get additional information (like the approx date of manufacture, the place of manufacture, temperature and tolerance codes, etc).

    Where size doesn't permit this, you may get an abbreviated part number (2SC1234 would often be printed as C1234 for example). For really small parts, the manufacturer might print a very short code (G3, for example).

    Sometimes, the manufacturer (or the person ordering vast numbers) doesn't want you to know, and they'll print a special code that only the manufacturer and the customer recognise. These make servicing a pain in the...
     
  3. Yoa01

    Yoa01

    214
    0
    Jun 18, 2012
    So without knowing manufacturer, I'm pretty much without knowing. I'm removing components from a power amp, which I also don't know the name of, so the chances of me figuring them out is near-impossible.

    Well, hey, they all kinda act the same, right? haha!
     
  4. davenn

    davenn Moderator

    13,246
    1,745
    Sep 5, 2009
    well not quite

    you cant use a BC546 in place of a 2N3055.
    The BC546 will prove to you, beyond a shadow of a doubt, that transistors are the fastest acting fuses on 3 legs

    Dave
     
  5. shrtrnd

    shrtrnd

    3,665
    453
    Jan 15, 2010
    I'm in the States.
    While manufacturers often put their own numbers on devices, those that can be, are
    often cross-referenced to JEDEC numbers (Google it).
    I suppose it's difficult to understand when starting-out, but a lot of times you can cross
    a transistor with (as mentioned by *steve* and davenn), partial part numbers on the device,
    as to what series (regional standard, manufacturer) they come from.
    As to your question about a 'standard', it's like one automobile manufacturer complying
    with the part numbers of other competitors. They don't do it. You have to rely on the
    infinite number of cross-references available (on-line and elsewhere).
    You often can, however, put regional types in similar categories.
    This might be technically incorrect, but I organize mine by regional manufactuer.
    2N prefixes are JEDEC. 2SC 2SD types are Asian, BC is an example of European
    origin.
    Sorry if that's not what you wanted to hear. But don't be discouraged. HAVING a good
    selection of types may turn-out to be an advantage.
     
  6. Yoa01

    Yoa01

    214
    0
    Jun 18, 2012
    If I didn't already have 35 fuses... heh, but I don't want to know how you found that out!

    None of what I have seem to bear no resemblance to JEDEC standards, just going by codes (I don't have much of a way to test them). For the most part, I don't see me dealing with much over 15 volts (wattage and amperage varying), and these don't look like they want to explode under that.

    Thanks!
     
  7. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    Perhaps it is time for you to tell us what the markings were on the original transistors and we can help you find something suitable to replace them with.

    Beware that the order of the leads is important and that even in the same package, different transistors have them in different orders.

    Placing the wrong type of transistor in a circuit, or the right transistor in the circuit the wrong way can kill them.

    Also, placing the right transistor in the circuit the right way can still kill it if there is a fault somewhere else in the circuit.

    Even worse, there doesn't actually have to be a fault to kill the transistor. Some amplifiers have settings for bias, and if this is set incorrectly, it too can destroy the transistor.
     
  8. Yoa01

    Yoa01

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    Jun 18, 2012
    Oh, no, I'm not replacing anything, sorry, the amp is LONG dead. I mean like cracked PCB's and in a dumpster missing parts dead. I'm just using it for scrap and components, which do seem to work.
     
  9. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    OK, no problems then. Perhaps you can give a few examples of the markings on the devices and we can walk you through the steps of identifying them. Then you can do the rest yourself :)
     
  10. Yoa01

    Yoa01

    214
    0
    Jun 18, 2012
    I love how amazingly helpful this forum is!

    After removing all of them, I've found there are four different styles. '/' indicates a new line (most have two lines of text)
    1) D438/D-7C
    2)C536/F8E
    3) C1708/A81G
    4) 7150A-1

    The last one shares names with a larger model; this one seems to be somewhat uncommon. And, unless I'm testing backwards, they all seem to be NPN. Thanks in advance!
     
  11. CocaCola

    CocaCola

    3,635
    4
    Apr 7, 2012
    Just some quick guesses, as that is about all you will have unless you find manufacture (or rebranding) specific info...

    The C1708/A81G might be a diode...
    http://www.s-manuals.com/smd-files/pdf/b/bas19,_bas20,_bas21_t.pdf

    The C536/F8E might be...
    http://www.dz863.com/downloadpdf-xgmpnajuvdbs-BF824W.pdf

    The D438/D-7C might be a diode...
    http://www.diodes.com/datasheets/ds30261.pdf

    And the 7150A-1...
    http://szmjd.en.alibaba.com/product/521786796-200642645/_Transistor_7150A_1.html

    Note that Holtek list that part number as a 5 volt regulator, might be a re-used part number or?
     
  12. Yoa01

    Yoa01

    214
    0
    Jun 18, 2012
    I saw the Holtek, but that's a larger unit. The others are surface mount, which I should have specified these are not.
    IMAG0017.jpg
     
  13. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,174
    2,690
    Jan 21, 2010
    I'd say most of these are 2Sxxxxx.

    D438 looks like 2SD348 See pdf here. This was the second hit on google when searching for 2SD438

    Seeing the devices makes all the difference :)
     
  14. Yoa01

    Yoa01

    214
    0
    Jun 18, 2012
    That would makes tons of sense since this thing used about 80% Sanyo parts. I should have posted pics earlier.
     
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