Samlex SEC-1235 SM PSU

Discussion in 'General Electronics Chat' started by bwilliams60, Sep 14, 2014.

  1. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
    I have this Samlex power supply which has no output and I am going through the circuit and I have a couple of questions. I am not real familiar with working on PSU's o here is what I would like to know.
    1) Is it normal for 120VAC to be stepped up to 345 VDC after the rectifier on this type of PSU. If so, what is the purpose.
    2) This unit has two transformers on it and the second one has no output on it. I went to the input side and there is only about 15VDC on the input side. I compared it to another working unit and it was 60VDC. I traced the circuit back further and found two large switching transistors (2SC3320). I am pretty certain that one is bad as I can see a hairline crack and a black spot on the surface. What is the proper way to test this type of transistor?
    3) Does anybody know where I can get this transistor from in Canada or U.S.?
    4) Any other valuable information you can give me on this unit? I do not have a schematic, just following circuit board.
    Thank you in advance.
  2. longpole001

    New Member

    Sep 16, 2014
    if were me i would pull them both out , and do a chack to see if theyt are different for a start in the standard transistor test ,in cct will probably not help unless ones is really shorted
    2nd i would contact the supplier , if you can find them and ask for some assistance , never know they may help with a cct or at least sell you a service manual with one

    you dont say what the equipment is so not sure if its related to the above link
    clearly 15v is not correct if the other unit that works is 60 so something is asstray

  3. tom_s


    Jun 27, 2014
  4. bwilliams60

    Thread Starter Active Member

    Nov 18, 2012
    Yes Tom, you are correct. Wasn't getting any response on this one so reworded it and now I get lots of information on the other thread. Sorry, I would delete this one but not sure how to go about doing that.