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Thread: ALC68 strip down & clean - Help please

  1. #131
    Join Date
    Dec 2012
    Location
    Germany, Gießen
    Posts
    3

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    Hi
    I had some problems to with my logic Card too.
    Had to test it out of the PSU, if its only putting out a constant signal its maybe ok.
    The regulator only puts out a PWM signal if a current flows threw the Shunt resistor or a voltage ist applied.
    I used this circuit to test the card of my PSU: http://abload.de/img/eil4000g0i7b.jpg (large!)
    Maybe this Image can help you too: http://abload.de/img/bild0023hrlnego.jpg
    On my Logic card i have replaced the voltage regulators (with transistors) with a pair of 7815 and 7915 regulators.
    If you need measuring at some point on the PCB just ask
    V214 is a UA734HC on my PCB.
    Greetings from Germany
    Alex
    Last edited by Alexander; 04-27-2013 at 17:03.

  2. #132
    Join Date
    Feb 2011
    Location
    Knutsford, UK
    Posts
    286

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    Very useful! Sure this will help. Jim if you can't prove the logic card good with this pop in the post to me in a week & ill sort out for you.

  3. #133
    Join Date
    Jan 2008
    Location
    South Lincs, UK
    Posts
    2,625

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    Only just seen these Posts Alex/Adrian, sorry for the delay, I didn't get an email notification.

    I currently have a UA734HC in its way to me, should be here soon. I will replace that and do what you suggested Alex. If no joy then I will post it off to you Adrian.
    Thank you so much for the help, everyone!!!
    --------------------
    My Brain urt's!

    Continuously in Awe! of (H)Al, the Photonlexicon Font of Complete Knowledge - The (H)Al'PL Database of complete puss that no one needs to know or ever trusts as he ain't really got a Scooby doo about now't!

  4. #134
    Join Date
    Jan 2008
    Location
    South Lincs, UK
    Posts
    2,625

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    Would it be possible Alex if you could look at the attached picture and tell me what components are 1-7 on the diagram according to your board just to check mine are all OK please?
    When I was going through components on the board at the last Surfleet LEM, the resistor marked number 1 was reading strange, I replaced it but don't know if I replaced it with the correct value.
    Also, on your picture, what is the box marked OSC? Is that where to attach the scope too?

    Thanks.
    Attached Thumbnails Attached Thumbnails IMG_6516mod.jpg  

    --------------------
    My Brain urt's!

    Continuously in Awe! of (H)Al, the Photonlexicon Font of Complete Knowledge - The (H)Al'PL Database of complete puss that no one needs to know or ever trusts as he ain't really got a Scooby doo about now't!

  5. #135
    Join Date
    Dec 2012
    Location
    Germany, Gießen
    Posts
    3

    Default

    Shure...
    1 = 330k
    2 = UA741HM
    3 = UA741HM
    4 = 2N2905A
    5 = not present (replaced with 7915 regulator)
    6 = not present (replaced with 7815 regulator)
    7 = 1k

    Yeah OSC means Scope .

    On my PCB the resistor left of resistor 1 is missing, there aren´t even holes fpr it.
    I changed the +-15V discrete regulators with standart 7815/7915 voltage regulators.
    I desoldered the Optocoupler for current regulation within the limits of the Imax an Iidle potis.
    Replaced the optocoupler with a 25k potentiometer.
    http://abload.de/img/p1030583meaq8.jpg

    Greetings
    Alex

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