• Sound Technology 1700B

    From Trevor Wilson@21:1/5 to All on Mon Jan 3 12:09:29 2022
    Well, it's been a few years. My 1700B has decided to cease operation, so
    it really is time for a repair and full rebuild. Here's what I am planning:

    * Replace all electrolytic caps in the unit. One of the main filter caps
    is dead, so it's time to do the lot.
    * Replace all the carbon composition resistors. A quick check on half a
    dozen has shown a 15 ~ 25% upward drift. Why did ST use CC resistors?
    I've been using cracked carbon since the 1960s. I'm 68 years old and
    I've never deliberately used carbon composition resistors. Crazy.
    * I was going to replace the critical OP amps with LME49710 OP amps,
    but, well, you know. NLA. AD797s look like the best, available option.
    Any other suggestions?
    * Replace all the opto couplers.

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