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Thread: Adjusting Linear Power Supply?

  1. #1
    Join Date: Apr 2017

    Location: Bristol

    Posts: 166
    I'm Tony.

    Default Adjusting Linear Power Supply?

    Well I guess I should have known better but I took a punt on the following LPS from Chinese ebayer;

    http://www.ebay.co.uk/itm/1113288910...%3AMEBIDX%3AIT

    I specified 5v and 15v to use with my SBT and Beresford DAC and have today received a LPS that outputs 12v and 10v.

    Would this be adjustable in anyway or have I been sold a Pup
    VPI Scout 1.1, Ortofon Quintet Bronze, Lesbox Tube Phono Stage, Xiang Sheng Dac 01A, Modified Yaqin MC-100B and Reiver Edingdale SR

  2. #2
    Join Date: May 2008

    Location: Surrey

    Posts: 6,052
    I'm Rob.

    Default

    A schematic of the circuit would be helpful, but it may be that there is one 7810 and a 7812 regulator in the supply. There are two regs shown in the pics (one for each output I presume) These could be changed for regs giving the power output you require so long as the transformer secondaries, after rectification would support that voltage. I suspect that as the ebay page shows multiple voltages available that the transformers are probably the same for each application and the supply is regulated by the voltage regs. If they sent the wrong one, tell them and they should send you the correct voltage unit.
    Buy Bose...And get your parking validated!.

  3. #3
    Join Date: Feb 2013

    Location: W Lothian

    Posts: 43,949
    I'm Grant.

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    there are 2 grey little boxes with gold screws. the screws are the adjusters.
    Regards,
    Grant ....

    I've said it before and I'll say it again: democracy simply-doesn't-work
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  4. #4
    Join Date: Mar 2008

    Location: Dunfermline, Scotland, UK

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    I'm inthescottishmafia.

    Default

    If you look at the picture, next to the small green capacitors, there is a grey/green box with a small screw on the bottom corner. These are variable resistors which are adjusted to give the required output voltage. You need a multimeter and a small screwdriver. Measure the DC output whilst turning the screw on each until you have the desired output voltage.
    “Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”

    Hunter S Thompson

  5. #5
    Join Date: Mar 2008

    Location: Dunfermline, Scotland, UK

    Posts: 12,361
    I'm inthescottishmafia.

    Default

    Also, I would check with Stan that 1A is ample to run the dac.

    EDIT- just checked, should be fine.
    “Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”

    Hunter S Thompson

  6. #6
    Join Date: May 2008

    Location: Surrey

    Posts: 6,052
    I'm Rob.

    Default

    Quote Originally Posted by struth View Post
    there are 2 grey little boxes with gold screws. the screws are the adjusters.
    Should've gone to Specsavers.......
    Buy Bose...And get your parking validated!.

  7. #7
    Join Date: Apr 2017

    Location: Bristol

    Posts: 166
    I'm Tony.

    Default

    Thanks Guys,

    I managed to adjust the 12v side up to 14.9v which is the closest I could get without shooting up to 15.2v.

    The other side would not reduce below 10.7 but would go higher.

    Here's a pic of the supply.

    I'm not tech but I suspect that the right side is not the right transformer?
    Attached Images Attached Images
    VPI Scout 1.1, Ortofon Quintet Bronze, Lesbox Tube Phono Stage, Xiang Sheng Dac 01A, Modified Yaqin MC-100B and Reiver Edingdale SR

  8. #8
    Join Date: Oct 2012

    Location: NE England

    Posts: 4,175
    I'm Jez.

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    It won't work as there will be different mains transformers for the widely differing output voltages. You'll need to send it back.

  9. #9
    Join Date: Mar 2008

    Location: Dunfermline, Scotland, UK

    Posts: 12,361
    I'm inthescottishmafia.

    Default

    They may send you the right trannie if you ask, quicker than sending yours back then waiting for the other to come.
    “Music has always been a matter of energy to me, a question of fuel. Sentimental people call it inspiration, but what they really mean is fuel. I have always needed fuel. I am a serious consumer. On some nights I still believe that a car with the gas needle on empty can run about fifty more miles if you have the right music very loud on the radio”

    Hunter S Thompson

  10. #10
    Join Date: Apr 2017

    Location: Bristol

    Posts: 166
    I'm Tony.

    Default

    Well its working fine on the 15v side.

    Might be a blessing on the 5v side.

    Probably would have fried my SBT!
    VPI Scout 1.1, Ortofon Quintet Bronze, Lesbox Tube Phono Stage, Xiang Sheng Dac 01A, Modified Yaqin MC-100B and Reiver Edingdale SR

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