question ! lab power supply and lm3886 amp board ?

Discussion in 'Analog & Mixed-Signal Design' started by pastinsain, Jul 14, 2016.

  1. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    why can't my hp 10 amp 40volt lab power supply drive the lm3886 amp ?
    the lm3886 works great with the 26vdc power supply that came with it, but when I try to power it with the hp 6267b lab supply , the amp will work for just a second then shuts down . Ive tried 3 other lab supplies and all do the same thing.
    I have the current set up to 5 amps and the volts set to 26vdc and the amp shuts down every time.

    now my ta2024 amps work great with the lab power supplies. what gives?
     
  2. AlbertHall

    Well-Known Member

    Jun 4, 2014
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    As it is a 10A supply why don't you set it to 10A and see whether that works?
     
  3. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    I did that and the same thing happens
     
  4. benta

    Member

    Dec 7, 2015
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    Normally, the LM3886 needs +26 V and -26 V.
    It is possible to run it single,supply, but then the circuit needs to be configured so.
    Are you certain that it is set up to run single-supply?
     
  5. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    Yes the power supply that came with it powers both lm3886 boards , leads are 26+ , ground , neg
     
  6. benta

    Member

    Dec 7, 2015
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    So, have you thought about what "neg" is? Perhaps -26 V?
     
  7. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    That may be the answer -26v but why do the ta2024s work ok with the lab power ?
     
  8. AlbertHall

    Well-Known Member

    Jun 4, 2014
    1,872
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    The TA2024 is intended to run from a single supply.
     
  9. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    The 26v power that came with ithe lm3886 is a single supply . It powers both boards .
     
  10. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    I appreciate your help, but I can't make any since out of it
     
  11. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    I even tried connecting the lab power to just one lm3886 board and the same thing happens
     
  12. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    All three lab power supplies have the factory default jumpers connected.

    Maybe if I tried connecting the neg jumpers on the rear of supplies to gnd . ?
     
  13. benta

    Member

    Dec 7, 2015
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    I give up...
     
  14. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    Thanks , however, there is something about these lab supplies " the DC is different compared to the dc in an amplifier in regard to the lm3886.
    that is for sure . What that difference is I would like to know ? I originally thought the lab supplies would be the cleanest power source you could drive an lm3886 with. but thats not the case ! bummer.
     
  15. atferrari

    AAC Fanatic!

    Jan 6, 2004
    2,644
    759
    Test that PM amplifier with another capable PSU.

    Have you current limited your PSU? What is the setting?
     
  16. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    yes I have set the current to 2amps ,,3amps ,6amps 10amps and no go. I would like to think DC is DC. but not in this case.

    I have tries 4 different PSUs and the same result
    hp6267b
    lambda 345a
    Kepco JQE 36-15
    HP 6289a
     
  17. benta

    Member

    Dec 7, 2015
    101
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    OK, for the last time:
    the OP does not understand what a dual supply is.
    The LM3886 needs a dual supply. And the original power supply will deliver +26/-26 V.
    The lab supply only delivers +26 V. OK?

    Benta.
     
  18. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    the only dc power supply thats works is the one that came with the amp . What is so different about DC sources other than amp rating and regulated current limiting .
     
  19. pastinsain

    Thread Starter Member

    Aug 25, 2012
    160
    2
    The supply that works is the one that came with the amp. And it is a single DC supply.
     
  20. benta

    Member

    Dec 7, 2015
    101
    24
    So what is "neg"?

    A picture would help.
     
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