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Thread: Apple II

  1. #1
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    Default Apple II

    https://en.wikipedia.org/wiki/Switch...e_power_supply

    "
    Apple II is designed with a switching mode power supply. "Rod holt was brought in as product engineer and there were several flaws in Apple II that were never publicized."
    "

    This seems to imply flaws in the power supply; if so, does any one know what they were?

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    I seem to recall the +5 volt rectifier failing shorted.

    In any case, here is a link to an archived forum:

    http://www.vcfed.org/forum/archive/i...p/t-13620.html

    BEWARE: The non-Astec supply DOES NOT have bleeder resistors across the main filter caps. If they are charged it takes a LONG time to bleed off and represents a major shock hazard. It's DC voltage which will cause your muscles to clamp down, making it hard to release that board.

    Yes, I had 2 scars on my hand that took about 9 years to fade out from one of those non-Astec ones.

    If those aren't the fix, let me know. I've repaired a lot of those over the years when I used to work for a grey market Apple repair shop.
    Generally they are easy repairs...

    Astec unit: Replace 1 cap in the feedback section
    Non-Astec unit: Replace 1 cap and 1 resistor in the feedback section

    Beyond that, it's a matter of simply looking for shorted diodes - both the bridge rectifier or the low voltage side diodes. If the fuse is blown, it's the bridge rectifier.

    Those tidbits will fix 95+% of the Apple II+/IIe power supplies.

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    ashiekh (2 Weeks Ago)

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    Default

    As I recall, the Apple][+ (my 1st computer) was a line-oriented machine that only had 64k RAM because I put a memory card in SlotZot. It came with 48k.

    The old dear ran with line input. This was 1.5 decades before the Internet, and progress was fast in those days. A museum piece. A running Apple II is not worth resurrecting, IMO.
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    Default

    Quote Originally Posted by ehume View Post
    A running Apple II is not worth resurrecting, IMO.
    But a IIGS is!

    I played Hard Hat Mack and Jumpman for HOURS on that platform.

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    It would be worth fixing an Apple I computer:

    One of the first-ever Apple computers just sold for almost $500,000—take a look
    https://www.cnbc.com/2019/05/28/wozn...christies.html

    I do have an IMSAI 8080 computer I built from a kit in 1976 that worked last time I powered it up a couple of years age. It was worth around $2,500.00 or so last time I checked on eBay.

    I am planning on retiring in a few months. Maybe I will see if it still works at that time.

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    Doesn't Christie's take half the sale price?
    Last edited by ashiekh; 2 Weeks Ago at 03:09 PM.

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