Transformer Wiring scheme

Discussion in 'General Electronics Chat' started by Slobodan Trajkovic, Jun 30, 2016.

  1. Slobodan Trajkovic

    Thread Starter New Member

    Jun 30, 2016
    5
    0
    Hi,
    I have this Transformer from old amp but i cant figure out primer wiring..
    It have 250v and 110v input and i only need 250(240)V but i don't know how to connect it.
    [​IMG]
    Code (Text):
    1. 1 - Red
    2. 2 - Blue
    3. 3 - Brown
    4. 4 - White
    5. 5 - Orange
    6. 6 - Gray
    7. 7 - Red(Sec)
    8. 8 - Red(Sec)
    9. 9 - Blue(Sec)
    10. 10- Blue(Sec)
    Here is what i measured with my Ohm meter..
    Code (Text):
    1. 1-2 > 1.2Ohm
    2. 1-3 > 4.5Ohm
    3. 2-3 > 3.8Ohm
    4. ---
    5. 4-5 > 1.0Ohm
    6. 4-6 > 4.2Ohm
    7. 5-6 > 3.6Ohm
    8. ---
    9. 7-8 > 0.6Ohm
    10. 9-10> 0.8Ohm
     
  2. EM Fields

    Member

    Jun 8, 2016
    165
    28
    Looks to me like it's an audio output transformer for a vacuum tube stereo amplifier.
    7 and 8 are the outputs to one speaker, 9 and 10 are the outputs to the other speaker, 1,2,3 is the primary for one channel with a feedback tap to a screen grid, and 4,5,6 is its counterpart for the other channel.

    I could be wrong , of course, but If you want to stick with this and do some definitive testing, what test equipment do you have on hand and how well is your junk box stocked?
     
    Last edited: Jun 30, 2016
  3. Slobodan Trajkovic

    Thread Starter New Member

    Jun 30, 2016
    5
    0
    It was from Philips HiFi Sound Project 6000..
    If 1,2,3 is for 1 sec, and 4,5,6 is for 2 sec how do i chose from 110-250?
     
  4. EM Fields

    Member

    Jun 8, 2016
    165
    28
    What makes you think it's a mains power transformer?
     
  5. Slobodan Trajkovic

    Thread Starter New Member

    Jun 30, 2016
    5
    0
    It was connected to mains before(I pulled it out of old Amp) but i didn't remember how it was connected and now i can't figure out how..
    I'm software engineer I don't know this stuff very well :D
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    Its probably not a step up mains transformer, so the highest resistance winding is most likely the primary - if you have two identical highest resistance windings; its probably a "universal" transformer. You can put the two windings in series for 230V or parallel for 110V - be careful though; If you get the phasing wrong in series, nothing much will happen - if you get the phasing wrong in parallel; it'll let the magic smoke out!

    Start with them in series first as nothing can go wrong - if the secondaries are dead; the primaries are out of phase. Get them in phase and arbitrarily decide which end of each winding is the start and mark them with a bit of tape. If you need parallel - connect the two starts to the same terminal.
     
  7. Slobodan Trajkovic

    Thread Starter New Member

    Jun 30, 2016
    5
    0
    I don't need 110v so i will go for series but witch of those 6?

    Is smart to connect just 1,2,3 on mains and check output to find +/- and then repeat same with 5,6,7?
     
  8. ian field

    Distinguished Member

    Oct 27, 2012
    4,413
    782
    If you know what voltage any of the secondaries should be - power it up with another transformer matching that voltage and see which primary is closest to your mains voltage.

    Its not absolutely accurate, but the error should be small (ish) with no load.
     
    Slobodan Trajkovic likes this.
  9. Slobodan Trajkovic

    Thread Starter New Member

    Jun 30, 2016
    5
    0
    I know that it was used for 50VDC AMP(STK031)..
    I never thought about that. So i could connect sec and find out input wires..

    Thanks for help!

    Soo 4-6 is 62V, 4-5 is 6V and 5-6 is 52V on Input with 6V on Sec used as input with small Transformer...
    So i guess 4-6 is 240V and 5-6 is 110V, i will do the same for 1,2,3 and then connect it.
     
    Last edited: Jun 30, 2016
  10. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,498
    2,364
    If a mains transformer, the primary is usually the inner/first wound windings,
    It appears it might be the two blues and reds for the primary?
    If so it would usually be one blue and red in series and the other two for supply, 240v supply.
    Max.
     
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