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RIFA safety cap PME277 - x or y?

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    RIFA safety cap PME277 - x or y?

    Hi guys, new member here, trying to fix an 80s B&O TV which suffered a failure of the 0.1uf safety cap up by the power switch/fuse. This is clearly marked as x2. The replacements are half the size, but have the same rating.

    Having read about RIFA failure, I also ordered replacements for the other two caps. Now that they've arrived, I'm not sure they are correct. The originals are rated 4700pf, and are marked as follows

    40/085/21 GPF
    PME277 MB447
    CT5
    250V ~ MP
    LD2
    VDE reg nr 5201.212222

    Is this an X or Y cap? I have ordered X2, but can't remember how I decided on them over Y, and can't help but think I really needs to order Ys.

    Thanks in advance

    #2
    Re: RIFA safety cap PME277 - x or y?

    I'll try and attach a few pics
    Attached Files

    Comment


      #3
      Re: RIFA safety cap PME277 - x or y?

      X cap definitely just by the physical dimensions. X class caps are generally wide with short straight legs. Y caps are generally round with long, sometimes bent, legs.
      Originally posted by PeteS in CA
      Remember that by the time consequences of a short-sighted decision are experienced, the idiot who made the bad decision may have already been promoted or moved on to a better job at another company.
      A working TV? How boring!

      Comment


        #4
        Re: RIFA safety cap PME277 - x or y?

        Originally posted by Th3_uN1Qu3 View Post
        X cap definitely just by the physical dimensions. X class caps are generally wide with short straight legs. Y caps are generally round with long, sometimes bent, legs.
        Thank you but is that really so? It seems at the time the RIFA caps looked similar whether X or Y?

        Comment


          #5
          Re: RIFA safety cap PME277 - x or y?

          Just look at where the old caps are in the TV - across the line, on/off switch, to chassis etc. to know if X or Y is required. Lower value 4,700pF are usually Y-caps and go from mains to the set's chassis.

          The old Evox/Rifa caps are from an era before X and Y class and mains overvoltage Cat. II or III etc. were well established.
          So the transient voltage rating and test was not as good as today, and the part's size is not really a figure of merit because of the paper dielectric. I would use a modern film cap instead, something polypropylene.

          PME271 is rated X2, 275VAC w/paper dielectric and only 2,150VDC one-time factory screening test.
          PME277 no data anywhere they must have burned down a few houses.

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