Triac motor speed control question

Discussion in 'General Electronics Chat' started by precisionmarine, Apr 29, 2015.

  1. precisionmarine

    Thread Starter New Member

    Apr 27, 2015
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    I'm trying to repair a triac motor speed control circuit that is inoperable due to a power spike and is NLA from mfg. It's based on an AC16F triac that tests bad, the gate of which is triggered thru a TO-92 component marked N313. The outside leads of N313 are marked A1 and A2 on the board.
    I've not been able to find info for testing or replacement of N313, can anyone help?
    Thanks!
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you want to test a Triac off board then use a low voltage AC such as a small transformer 6v-12v etc connect the A2 to AC in and A1 to a suitable lamp to the AC return, then momentary connect a 33ohm resistor from G to A2 and the lamp should light if the Triac is good.
    Equivalent replacements are available from DigiKey.
    Max.
     
  3. precisionmarine

    Thread Starter New Member

    Apr 27, 2015
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    Max, thanks for the reply. I may not have been clear, but I know the triac is bad. I need help identifying the N313 component and sourcing a replacement.
    Did I supply enough info, or is a schematic needed?
     
  4. MaxHeadRoom

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    Jul 18, 2013
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    Last edited: Apr 29, 2015
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  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Could N313 be a low-current triac used to trigger the main triac? More likely though a Diac, as Max says.
     
  6. precisionmarine

    Thread Starter New Member

    Apr 27, 2015
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    Thanks for replies. In retrospect I should've mentioned N313 has 3 leads with center lead active in the circuit , so a small signal triac is possible. I cannot find a spec sheet or other info online foe N313. If a schematic is needed I'll have to post one tomorrow when I'm at home.
     
  7. MaxHeadRoom

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  8. ian field

    Distinguished Member

    Oct 27, 2012
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    There's an old tradition of using a diac in the gate circuit - but the American semiconductor industry came up with all sorts of variations on the 4-layer device theme.

    You could maybe try the DB3 diac:

    http://www.farnell.com/datasheets/1689752.pdf
     
  9. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    can you see which pins the to92 connects to on the main triac, is it G to MT2...
     
  10. precisionmarine

    Thread Starter New Member

    Apr 27, 2015
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    Ddave, the gate of the AC16F triac is connected directly with what is labeled A2 (on the pcb) of the unknown component N313 (a TO-92 based component)
    So I'm trying to identify N313 for testing/possible replacement. Best guess so far looks to be a small signal triac. I'll upload a circuit drawing tomorrow if I haven't figured it out.
    Thanks for all the interest and replies, I appreciate the effort on my behalf!
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    The most likely is a small signal triac with no external connection to its gate - its triggered by a specific breakover voltage.

    Or in other words - a diac.
     
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  12. MaxHeadRoom

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    According to this it sounds to me like all 3 terminals used? UJT etc.
    Max.
     
  13. ian field

    Distinguished Member

    Oct 27, 2012
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    Don't forget there's the UJT and the PUT (programmable unijunction transistor) - which is actually not a unijunction at all, its a thyristor with the gate at the wrong end.
     
  14. precisionmarine

    Thread Starter New Member

    Apr 27, 2015
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    Success! Turned out to be a small signal thyristor used to trigger the triac. Replacement arrived and circuit functions.

    Thanks for all the replies!
     
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