Connect with us

Sewing machine speed controller repair

Discussion in 'Troubleshooting and Repair' started by whiteoutage, Dec 29, 2018.

Scroll to continue with content
  1. whiteoutage

    whiteoutage

    25
    1
    Jul 20, 2017
    I have a used electronic speed controller(model N) from a brother sewing machine. Input voltage to controller is 120V but output voltage is nada, zip, zero. Does not matter if pressed to floor or not, still no voltage. I'm a nob at electronics but good at replacing components if problem(s) can be discovered. I do have a simple capacitor tester and all three tested ok within specs. Attached are pics of board. If someone could enlighten me as to further multi-meter tests to try I'd be eternally grateful
     

    Attached Files:

  2. whiteoutage

    whiteoutage

    25
    1
    Jul 20, 2017
    Correction, there is no voltage going to the board, only voltage coming from mains. I have continuity from pin 2 to neutral on board and continuity from pin 3 to line on board but voltage does not register either on pins 2 or 3 or on board solder points of line and neutral. Not sure what this means. Maybe cord is bad, maybe other board component? By pins 1,2,3, I mean the cord(see picture)
     

    Attached Files:

  3. whiteoutage

    whiteoutage

    25
    1
    Jul 20, 2017
    Wondering if I need to place a load on pins 2 and 3 somehow, then test voltage? Forgot to mention that I no longer have the machine. I just want to know if speed controler is working.
     
    Last edited: Dec 29, 2018
  4. Bluejets

    Bluejets

    3,784
    783
    Oct 5, 2014
    You could try putting a test lamp on the load.(normal 120v tungsten bulb, say around 60W)
     
  5. Alec_t

    Alec_t

    2,759
    735
    Jul 7, 2015
    Have you checked if any fuse present in the plug/cable/pedal is good?
     
  6. whiteoutage

    whiteoutage

    25
    1
    Jul 20, 2017
    No fuses to be found on this cheap board (looks to me as though they bypassed what was supposed to be a fuse and just put a wire across it?). i don't have a tungsten lamp - can i use 60 watt incandescent instead? (remember i'm a electronics knob :-(

    I unscrewed the board and added a pic of back side of board. Do these types of speed controllers need a load to receive power from the mains, or could I have a component failure?
     

    Attached Files:

    Last edited: Dec 29, 2018
  7. Alec_t

    Alec_t

    2,759
    735
    Jul 7, 2015
    That is a tungsten (filament) lamp.
    The most likely component on that board to fail is the semiconductor device (arrowed) :-
    tempsnip.png
     
  8. 73's de Edd

    73's de Edd

    2,805
    1,176
    Aug 21, 2015
    Sir whiteoutage . . . . .

    Just two wires are being involved with the dimmer power control path in the submited explanation.
    HOT AC line power comes down and passes thru the lamp then passes down into the dimmer as the PURPLE DOT path unitil it reaches the TRIAC power controller YELLOW RECTANGLE.

    Other photo

    As the foot switch rollers move to the right the speed / lamp intensity should increase.

    First photo

    The returm power path is made via the BLUE DOT path.
    If no control, your placing of a jumper wire across the triac terminals marked with the RED bar should give full lamp brightness if there are no wiring problems.

    If not . . . expect the need of replacement of previously mentioned YELLOW RECTANGLE triac . . a la . .most honnable . ..alex_teeeeeeeeeeeeeeee.

    Thassssssssssssit . . .

    REFERENCING . . . . . . . compliments of the DUMMY patrol . . . . buy their books . . . . .

    [​IMG]


    Kids in the back seat can cause accidents . . . . . . . . . accidents in the back seat cause kids.
     
    Richard9025 and Tha fios agaibh like this.
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-