Help specifying a replacement transformer

Discussion in 'Power Electronics' started by Qwiksilvr, Oct 9, 2016.

  1. Qwiksilvr

    Thread Starter New Member

    Oct 9, 2016
    3
    0
    Hi all,

    I'm currently trying to repair an electronic motor controlled massage table which has stopped working.

    Looking over the fairly basic control board, two diodes and the bridge rectifier have seemingly failed open.

    Looking over the transformer, the primary winding isn't showing any continuity and there's a very low AC voltage detected on the secondary winding when powered. Presumably it's at least partly to blame for the problem.

    I can find replacement diodes and the bridge rectifier easy enough, but I'm having trouble locating a replacement transformer. The code noted on the unit is HWX-66-36-01 which unfortunately doesn't reveal any replacement sources. The attached sticker states an input of 220V (50Hz) and an output of 24V, ultimately driving a 24V DC 3.5A motor. The transformer itself is fairly small (65 x 65 x 55mm).

    There seems to be a massive plethora of transformers out there capable of meeting the 220V-24V part of the step down, however I'd be very grateful for some guidance narrowing the choices down a little in terms of the spec I'd need.
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,452
    3,371
    Farnell has CTFCS100-24U rated at 2A.

    A larger transformer CTFCS200-24U is rated at 4A but no longer stocked. You can contact Farnell and see if they can supply it.

    Both transformers come with two secondary windings. For a bridge rectifier, you will need to connect the two windings in parallel, making sure to wire them in phase.

    How many secondary windings are on the original transformer?
    Can you post a photo of the transformer, showing the leads or connections?
     
  3. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,571
    2,382
    150va should work.
    Look for Hammond or a local electrical supplier for small control TFMR.
    Max.
     
  4. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,813
    1,105
    I'd be asking myself "Why did the tranny, diodes and bridge rectifier fail?". You don't want to replace them, only to have them fried when you switch on. Have you tested the motor for shorted windings?
     
  5. Qwiksilvr

    Thread Starter New Member

    Oct 9, 2016
    3
    0
    Many thanks for the rapid replies. NB: I've checked the fuse in the fuse holder (and the holder itself).

    Pics as requested:

    [​IMG]
    [​IMG]
     
  6. Qwiksilvr

    Thread Starter New Member

    Oct 9, 2016
    3
    0
    Unfortunately I don't have my power supply with me to give the motor a powered test. The motor itself is connected with a 4 pin DIN plug, getting a resistance of 0.4 between two pins and 5.1 between the other two.
     
  7. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,571
    2,382
    Thermal fuse buried in the primary.
    Max.
     
  8. MrChips

    Moderator

    Oct 2, 2009
    12,452
    3,371
    Just going by the size of that transformer I would wager that the CTFCS100-24U from Farnell would do the job.
     
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