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    ST 70 bad cap

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    wttaylor

    Posts : 3
    Join date : 2010-03-06

    ST 70 bad cap

    Post by wttaylor on Wed Dec 12, 2012 6:15 pm

    Hi, all, I don't normally write on the forums but I am perplexed. I have an ST 70 running virtually stock (hexfreds for rectifier, SV board with Vishay, Caddok, MIT, etc) external filament supply, Rubies. After 40 + years I decided I should change the quad cap on GP. I purchased two CE caps from a well known vender in 2009. I installed it and then tested my old one. Capacitance was higher than expected and the ESR was a little high. Last Sunday while listening I heard a bad noise. Thought at first it was the preamp but no. Bias voltage low. The 30Mfd section had died (150nf, 34.269K ESR). I installed the other one (intended for another ST70 I have not started on yet)and all is good. The question is about the date code firstly and secondly CE caps. I am guessing the 0511-01 is the date code. If that's the case, I purchased old stock in 2009. I have read of quite a few of these modern CE caps croaking early. Any ideas? I am getting ready to VTA the other ST70 and I see it uses the same brand cap. Best Wishes to all, Bill Question

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