Power Transformer Testing Question

Discussion in 'Shock Brother's DIY Amps' started by ArcticWhite, Jun 13, 2021.

  1. ArcticWhite

    ArcticWhite Tele-Afflicted

    Posts:
    1,366
    Joined:
    Apr 14, 2009
    Location:
    Portland Oregon
    I just tested this PT pulled out of a Hammond S6 Chord Organ.
    The red HT wires yield 780 VAC between them, with no load applied.
    Does that mean this is a 390-0-390 transformer?
    Yeah, this is a dumb question, but I just spent an hour searching Google, and I'm still just as dumb.

    20210613_172230.jpg 20210613_172222.jpg
     
  2. Lowerleftcoast

    Lowerleftcoast Friend of Leo's

    Posts:
    3,960
    Joined:
    Dec 30, 2019
    Location:
    california
    If there is no load on the PT the voltage will read higher. Conventional wisdom is: the rated voltage is *as stated* when there is a load of X amps.

    If there is a HT center tap then a 780VAC (CT) can be denoted as 390-0-390.
     
  3. dogmeat

    dogmeat Friend of Leo's

    Age:
    70
    Posts:
    2,878
    Joined:
    Oct 12, 2017
    Location:
    Alaska
    yeah if there is a center tap
     
  4. ArcticWhite

    ArcticWhite Tele-Afflicted

    Posts:
    1,366
    Joined:
    Apr 14, 2009
    Location:
    Portland Oregon
    Yes, there is a CT.
    Thanks guys.
     
  5. ok_state_blues

    ok_state_blues TDPRI Member

    Age:
    33
    Posts:
    24
    Joined:
    Mar 21, 2021
    Location:
    USA
    I have a similar pt that I just got no long ago and got the same measurements. What's your plan for you pt? Just curious if you have a certain circuit in mind or will try to drop the voltage to make it compatible with another.
     
  6. ArcticWhite

    ArcticWhite Tele-Afflicted

    Posts:
    1,366
    Joined:
    Apr 14, 2009
    Location:
    Portland Oregon
    Planning to sell it.
    It's too heavy and large to use in a 15 watt amp, which is big enough for me.
     
    ok_state_blues likes this.
  7. gusfinley

    gusfinley Tele-Afflicted

    Posts:
    1,434
    Joined:
    Jun 11, 2014
    Location:
    SLC, UT
    If you have a schematic you might be able to back out the primary voltage based on the rectified DC output.
     
IMPORTANT: Treat everyone here with respect, no matter how difficult!
No sex, drug, political, religion or hate discussion permitted here.