USB Universal Drive Adapter

Discussion in 'A+ Certification' started by teak, Apr 25, 2010.

  1. teak

    teak Guest

    I have two good old harddrives. I cannot place them in my Compaq
    I need a good quality USB/UDA. I ahve one but is is a reral piece of
    junk. Ayone know where I could get a quality USB/UDA?

    teak, Apr 25, 2010
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  2. They are all pretty much the same, and they generally all work ok. You
    may have a bad one ... the "build quality" of these is poor. Out of
    about 5, I've had one with a bad USB/IDE converter (which I fixed; the
    USB/IDE chip was poorly soldered) and one with a bad power supply (it
    superficially worked, but failures occurred whenever I used it).

    Best place to buy them is on E-Bay unless you need one fast, because
    most of them ship from China or Hong Kong by boat (2-3 weeks).
    Barry Watzman, Apr 25, 2010
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  3. teak

    Bill Eitner Guest

    I agree.

    I work at a shop where we use those.
    We always buy them 2 at a time, and
    when one fails buy 2 more. That's
    the way it is with dirt cheap Chinese
    electronics. I also agree e-Bay is
    the source for the cheapest direct-from-
    China products.
    Bill Eitner, Apr 25, 2010
  4. teak

    Bill Eitner Guest

    Attn: Barry Watzman

    I generally agree with your posts.
    You have a site or any online technical
    tutorials a man could take the time to read?

    I started in on the forums in '96 with Usenet.
    I carry amateur and commercial radio licenses
    as well as the A+. My background is obviously
    radio, and not as obviously component-level
    repair of amateur-grade radio equipment and
    consumer-grade electronics in general.

    I have hosted online tutorials, but they are
    quite specialized and probably of no interest
    to you. My old specialty and how I made a
    living was CB radio. The mysterious illegal
    side of CB radio was where the money was/is,
    so that's where I hung my hat. In time I
    got tired of it and wanted to go legit.

    So here I am--or here I was--I've been legit
    for a couple of years now.

    I suppose my point is: I'm still interested
    in high power. With PCs that's the power
    supply. I've been looking for the ideal
    tutorial on PC power supply design and testing.
    I'm coming up with a mixed bag. Namely that
    there are a number of topologies and I (a guy
    who is better with linear supplies than switching
    supplies) should be able to recognize and be
    comfortable with all of them.

    Is that true? If so, okay I have some catching
    up to do. Maybe you can help me with that as
    well. I teach interns that come from a local
    vocational school. They all say their time with
    me teaches them more (in two months) than the
    school did (in six months). I expose them to
    the innards of CRT monitors and power supplies.
    I want them to be competent and unafraid.

    I can keep going, but I'll let it go here.
    If you think you can help me in any way, let me

    I work for a refurbisher/recycler.

    We refurbish donated computer equipment and
    sell it cheap or give it away.

    We also maintain a free municipal area wireless

    I agree.

    I work at a shop where we use those.
    We always buy them 2 at a time, and
    when one fails buy 2 more. That's
    the way it is with dirt cheap Chinese
    electronics. I also agree e-Bay is
    the source for the cheapest direct-from-
    China products.
    Bill Eitner, Apr 27, 2010
  5. In a nutshell, all switching power supplies work pretty much the same:
    The incoming line is full wave rectified and crudely filtered
    (capacitor) to DC. The DC is "chopped" on and off through the primary
    of a pulse transformer. The secondary (secondaries, in many cases)
    provide the output. Since the switching frequency is 20khz to 100khz,
    relatively very tiny capacitors provide very high quality pure DC
    output. ONE of the outputs is monitored by a circuit that compares it's
    output voltage to the desired voltage, and this is used to change the
    on/off duty cycle of the primary switching circuitry to keep that
    output's voltage within 5% or so of what it should be. The voltages of
    the other outputs, if any, are simply a function of the relative turns
    ratios of their secondary windings on the pulse transformer (e.g. they
    are not individually regulated, per se).

    If you ever worked on vacuum tube car radios in the 1950's, you will
    recognize this a the 70 year old "vibrator" power supply, only with
    solid state electronics replacing the "vibrator", incorporating feedback
    and pulse width modulation to [precisely] control the output voltage.
    Barry Watzman, Apr 27, 2010
  6. teak

    Bill Eitner Guest

    That's for the input.

    I understand the fundamentals. Over the years I've purchased
    a few books, but their theory and designs are not specific
    to my current interest. I'm looking for PC power supply
    specifics so I can put together a troubleshooting and repair
    flowchart that I can teach to the interns. Right now we
    repair about 50% as bad caps and semiconductors that fail
    as shorts are visual. Change out the bad looking parts and
    the supply will generally work again. Now I'm looking to
    be able to repair 40-45% of the remaining 50% as well as
    being able to show the differences between units that are
    more likely to be reliable at a given output. Right now
    I simply pass along that a difference in weight can matter.
    For example, compare a Dell 250 watt unit that weighs twice
    as much as a cheap 400 watt (so says the sticker) unit.
    Now I want to be able to point out the specific differences.
    As time permits I've been working my way through this site:
    So far it looks pretty good.

    The other project is the same sort of deal but with LCD
    monitors. Right now if it's not a signal processing issue
    and online research of the specific brand and model points
    to soldering, bad caps, semiconductors in the power supply,
    we more often than not repair it. However, that still leaves
    a large percentage unrepaired that could likely be repaired
    if my understanding was greater.

    Thanks again,

    Bill Eitner
    Bill Eitner, May 2, 2010
  7. teak

    Bill Eitner Guest

    There you have it. Or the claimed 400 watt supplies we
    bought a case of for no more than $15 a piece are exactly
    what we paid for.

    I'm at a wall. I need the specific knowledge and tools
    to break through. I want to be able to tell the difference
    and show my work.
    And it was only a 63 watt supply?! That can't be right.
    The ICs in an IBM PC were lined up row after row.
    You're telling me the whole mess ran off of a 63 watt
    (and why not 65 or 80 or 100 watt) supply? Maybe 163--
    something like that. I always thought the original
    supplies were over a hundred watts--because they needed
    to be to feed the acre of chips--and switching type
    because IBM engineers of the time could make it happen
    with improved overall efficiency.
    Thanks for that. Shorted ceramic capacitors; that's one
    I certainly wouldn't look for early on. As an RF repair
    tech, ceramic cap failures are the last thing I look for.
    I've seen them blown open (cracked open ceramic causing
    a larger gap between the plates and reduced capacitance).
    Having a ceramic cap fail so as the plates come together
    to form a short would be a new one for me.

    To me, open resistor means burnt open which we can deal
    with now (thankfully).
    Where did you start/what did you start with?
    Okay. So I need to be teaching circuit understanding.
    Not really practical within a 2 month internship but
    understandable in this context.
    You know what I'll find--the LCD monitor equivalent of
    you. And he'll say a generalized flow chart isn't possible
    even when I know he could create it (just like you could
    with PC power supplies).

    The bottom line is: if you can fix a particular device without
    a schematic 99% of the time, you can produce a flow chart of
    how you do it.

    For a long time my gig was CB radio. I was in it for decades
    and got so good at some of the common yet popular tasks that
    I wrote concrete tutorials that took away all the mystery.
    I shared them with a popular site. They are dated now, but
    are still there as proof:

    Help me move on.
    Bill Eitner, May 8, 2010
  8. The original IBM-PC supply was made by Zenith (the old TV maker, also
    the owner of Heathkit and Zenith Data Systems), not Astek (which did,
    however, become a supplier later).

    [I worked for Zenith at the time]
    Barry Watzman, May 8, 2010
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