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Thread: VR201 Repair Opinions

  1. #11
    Join Date
    Mar 2008
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    Westchester County, NY
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    Very Good! Bad caps again! I am getting the feeling that capacitors are the singlemost common cause of failures in electronics anymore.

    The sharpness looks beautiful with the bad RTV cleaned out from the coverglass. Really nice and clearer than when the tube was new (I think that RTV always made things look hazy.)

    Lou

  2. #12

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    Quote Originally Posted by Lou - N2MIY View Post
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    Very Good! Bad caps again! I am getting the feeling that capacitors are the single most common cause of failures in electronics anymore.
    Yeah, this is true - period. MTBFs on electrolytics are responsible for the vast majority of failures. It got a lot worse when PCs converted to linear regulators on motherboards during the PIII phase and later. Capacitor manufacturers were cheating their temperature specs.

    In the telco equipment industry, many specs mandate all power supplies be constructed without electrolytics at all. Tantalums were also a big no.

    Of course reverse polarity installation doesn't help. I've seen reversed tantalums turn to ash without any other sign of problem. Electrolytics tend to burst in power supply filter situations, but in small signal instances where potentials are low enough they just go leaky or short. Open caps happen too, but I've not discerned any common causative factor.

    Instances of non-polar cap failure (like in my BA23 supply a few years back) are fairly rare in my experience. In that case, being right across the AC line, I tend to think long term moisture infiltration is partially responsible, or perhaps just the drying and aging of the encapsulation material. (some sort of molded epoxy or polyester?)


    Reminds me - what are the temp specs on those new caps? Specific manufacturers and sources might be nice to share too. Nothing is available locally around here any more - everything mail order.

    Your persistence is admirable - congrats on the victory. Very clean.

  3. #13
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    I didn't look at the temp ratings of the caps when I purchased them but I believe they're all generic ratings. The monitor doesn't really get all that warm when in use.
    = Excellent space heater

  4. #14
    Join Date
    Apr 2018
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    Fort Worth, TX
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    Hmm... I replaced the caps in my VR201 recently as well. I also noticed that C6 (10uF 250V) and C211 (47uF 30V) were backwards on the board.

    I flipped them around to no avail. I seem to be having the same problem you were experiencing. Maybe next weekend, I'll open it back up and double check my work.

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