Roe caps in c32

Discussion in 'McIntosh Audio' started by rollcentre, Apr 10, 2018.

  1. rollcentre

    rollcentre Boom-tizzz

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    I am going to recap my c32, from what I gather this preamp was probably built in late 78 or 79. I notice that the little brown 10mfd-40v and 10-63 ROE caps on the tone control board, and a few other places. They are marked with + and -, I was under the impression that these were bipolar electrolytics , there is no polarity marking on the schematic. I was going to order some more caps to replace them (nichicon ES bpe). I already have some polar electrolytics (elna silmic ii) that are pretty good sounding. I'd love to use them there, but I wanted to confirm I can in fact use a polar e cap there and orient them the same as the ROE caps I'm removing. I'm a bit unfamiliar with that type of cap

    Thanks !
     

     

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  2. gslikker

    gslikker Super Member

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    A quick google looks the bipolars, if it is the radial brown ones, to be marked EKU on top.
    Otherwise you will see at least a "plus" sign on top and usually marked "EK".

    Just google Roederstein eku and select the pictures
     
  3. rollcentre

    rollcentre Boom-tizzz

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    Thanks!
    I'm glad you said something, I saw that the 63v caps are the EK polarized version, both of which are cracked and leaking electrolytic goop. o_O the schematic has them as bi polars. Hmm.

    The rest of them are 40v caps are indeed the EKU non-polar.

    I had a polarized one on an mr78 power supply board, failed in the same manner. The Bakelite case cracked and goop leaking.
     
  4. rollcentre

    rollcentre Boom-tizzz

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    Mouser is sold out currently of the cap I want to use, they won't have them til next month, does anyone have 12 or so nichicon Muse ES bipolar electrolytic caps in 10uf 50v they can spare?
     
  5. jlovda

    jlovda Things I loved from the 60's and 70's Subscriber

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    Digi-Key has them. If you have never purchased from them, they are almost exactly like Mouser.

    https://www.digikey.com/products/en/capacitors/aluminum-electrolytic-capacitors/58?k=nichicon+es&k=&pkeyword=nichicon+es&pv2049=u10µF&pv2079=u50V&FV=ffe0003a,ffecc981&quantity=0&ColumnSort=0&page=1&pageSize=25
     
  6. rollcentre

    rollcentre Boom-tizzz

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  7. CohibaJoe

    CohibaJoe AK Subscriber Subscriber

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    When Terry recapped C32, 6100, 1900...All the ROE's had been replaced Nichicon ES.
     
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  8. rollcentre

    rollcentre Boom-tizzz

    Messages:
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    Location:
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    Thank you sir! I believe it was your thread I'm using as a go-by for the rebuild of mine. The noise floor is a bit higher than it's supposed to be at idle on all settings, except for when I dial in the expander. It really stands out with my more sensitive speakers. I think i remember reading something Terry wrote saying that replacing the ROE caps in these units can lower it considerably. It's really one of the last things I really have to do on mine. I already replaced the bridge rectifier diodes with new 400v/1a diodes and the voltage regulators for the 18v supply. No change in noise floor (hiss) unfortunately. I'm starting to wonder if it could be a faulty SCR for the auto turn on function. I replaced the ribbon cables and all other e caps besides the ROEs so far. Also replaced some opamps with low noise ones.
     

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