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RIFA PME 271M - there are so many!

Discussion in 'General Electronics Discussion' started by RWD3M, Apr 22, 2019.

  1. RWD3M

    RWD3M

    6
    1
    Apr 22, 2019
    Hi everyone

    I'm more usually found on the various welding and mechanic'ing (if that's a word) forums so am a little out of my comfort zone here!

    I'm here because my trusty old Vax 2000 has failed (whilst my dearly beloved was using it to hoover up the entire street by the sounds of it!) and is making a funny smell. It sort of runs but but slower and not smoothly.

    I think I've traced the fault to an exploded capacitor (tried to attach a pic but get an error message) and, whilst I have got some numbers from it, I'm at something of a loss as to how to establish what replacement part I need. I'm hoping someone here can help.

    The capacitor in question is a RIFA PME 271M and has the following additional numbers on it: 40/085/56, 0.22uf x2 and CB4. I've found loads similar on the bay and elsewhere but none that actually match these numbers. They are similar but typically read 40/100/56 or 40/110/56.

    Anyway, here's hoping.

    Regards,

    Richard.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,053
    1,818
    Nov 17, 2011
    Too big? Try downsizing the image, that usually helps.

    As long as the replacement capacitor has:
    - X2 rating
    - 0.22 μF capacitance
    - 275 V (AC) rating
    - matching pitch
    it should work.
     
  3. Martaine2005

    Martaine2005

    2,233
    604
    May 12, 2015
    Hi there,
    An X2 cap is invariably placed across the AC before other components. It’s a safety cap and filter.
    You can remove this and see if the problem goes away. It normally fails as a short and blows the fuse (not always).
    Have you checked across it for a short?.

    Martin
     
    davenn likes this.
  4. Martaine2005

    Martaine2005

    2,233
    604
    May 12, 2015
    I see Harold typed as I was typing

    Martin
     
  5. AnalogKid

    AnalogKid

    2,283
    646
    Jun 10, 2015
    40: -40C ambient temperature worst case - larger number is better

    085: +85C ambient temperature worst case- larger number is better

    56: number of days of the damp heat test- larger number is better

    X2: insulation/application class. X2 is a medium-grade line-to-line filter capacitor.

    CB4: Could be a mounting code. Are you sure it isn't C4B? Does the old cap have wire leads or lug terminals?

    ak
     
    Harald Kapp likes this.
  6. RWD3M

    RWD3M

    6
    1
    Apr 22, 2019
    Harald, Martin, ak,

    Thank you so much for your replies. I'm writing this on my tablet thing but will get on the computer and reply properly tomorrow evening.

    Richard.
     
  7. Bluejets

    Bluejets

    3,385
    681
    Oct 5, 2014
    Sounds more likely the armature in the motor has a couple of burnt out windings.

    Cap is probably just a side effect problem.
     
  8. RWD3M

    RWD3M

    6
    1
    Apr 22, 2019
    Hi all,

    Harald, I made them smaller and it seems to have worked.
    20190422_155112_small.jpg 20190422_155126_small.jpg
    Martin, Checked and it's open circuit.
    ak, thanks for the explanation of the numbers. It's definately CB4, but I have no idea what that means. the wires are crimped into the spade connectors that connect to the switch.
    Bluejets, I do hope not. Having said that, motors are available if I need one.

    I've ordered this one which will hopefully do the job.

    https://www.ebay.co.uk/itm/PME271M6...360973?hash=item564a2894cd:g:7vIAAOSwp-RaYJds

    Does it matter which way it's connected?

    Thanks so much for all your help, I am very grateful.

    Richard.
     
  9. Martaine2005

    Martaine2005

    2,233
    604
    May 12, 2015
    That one you ordered is perfect.
    It doesn’t matter which way it is connected. It is not a polarized capacitor.

    Martin
     
  10. RWD3M

    RWD3M

    6
    1
    Apr 22, 2019
    Thanks Martin.
    I will report back at the weekend on my success or failure.
    Richard.
     
  11. Martaine2005

    Martaine2005

    2,233
    604
    May 12, 2015
    Hi Richard, please think about what @Bluejets said too. It is very valid.
    ie- if that cap was shorted, the motor wouldn’t work at all.
    So an unfamiliar smell and motor loading could be armature failure causing plastic surroundings to overheat. Lets hope the smell was cap plastic melting!.

    Martin
     
  12. RWD3M

    RWD3M

    6
    1
    Apr 22, 2019
    Absolutely Martin.

    As I mentioned, motors are available if it comes to it but I'll go for the cheaper option first.

    I'm keeping my fingers crossed.
     
  13. Martaine2005

    Martaine2005

    2,233
    604
    May 12, 2015
    Fingers crossed here too
    Either way, it’s a learning experience!.

    Martin
     
  14. RWD3M

    RWD3M

    6
    1
    Apr 22, 2019
    Hi guys,

    The capacitor arrived yesterday, I've just fitted it and to my genuine amazement all appears well in Vax world!

    Normal service appears to have been resumed and I can't tell you how gratefull I am to you all.

    Many heartfelt thanks.

    Best Regards,

    Richard.
     
    Martaine2005 likes this.
  15. Martaine2005

    Martaine2005

    2,233
    604
    May 12, 2015
    That's great news. Well done :)

    Martin
     
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