54520A repair

Discussion in 'Electronic Repair' started by jvadillo@gmail.com, Apr 16, 2007.

  1. Guest

    Hello all,

    I recently purchased a broken 54520A hoping to be able to repair it.
    The seller said that the screen was faulty. However, after the
    oscilloscope arrived, I saw very soon that the problem was not the
    screen but something else.

    When the oscilloscope boots, the fan turns on and all the indicators
    on the front pannel light-on. But it hangs there. No keyboard response
    and nothing displayed on the screen. However, the screen is working,
    as when I turn off the device, sometimes I can see the beam on the
    display and some noise.

    The indicators keep lighted on until you turn the oscilloscope off
    again.

    Could anybody help me? Its a great oscilloscope, but it just does
    not work :-(

    Juan
     
    , Apr 16, 2007
    #1
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  2. James Sweet Guest

    wrote:
    > Hello all,
    >
    > I recently purchased a broken 54520A hoping to be able to repair it.
    > The seller said that the screen was faulty. However, after the
    > oscilloscope arrived, I saw very soon that the problem was not the
    > screen but something else.
    >
    > When the oscilloscope boots, the fan turns on and all the indicators
    > on the front pannel light-on. But it hangs there. No keyboard response
    > and nothing displayed on the screen. However, the screen is working,
    > as when I turn off the device, sometimes I can see the beam on the
    > display and some noise.
    >
    > The indicators keep lighted on until you turn the oscilloscope off
    > again.
    >
    > Could anybody help me? Its a great oscilloscope, but it just does
    > not work :-(
    >
    > Juan
    >



    I assume this is a DSO? Start with the simple stuff, check the power
    supply voltages, see if the CPU clock is running, have a look at the
    reset line, that should provide some insight.
     
    James Sweet, Apr 16, 2007
    #2
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  3. Guest

    Yes, its an HP 54520A digitizing oscilloscope.

    I will check if all the voltages are OK. According to the service
    manual I have to search around for a 2 Ohms 25 Watt resistor to load
    the power supply.

    I will post my results here.

    Juan

    On 17 abr, 00:38, James Sweet <> wrote:
    > wrote:
    > > Hello all,

    >
    > > I recently purchased a broken54520Ahoping to be able to repair it.
    > > The seller said that the screen was faulty. However, after the
    > > oscilloscope arrived, I saw very soon that the problem was not the
    > > screen but something else.

    >
    > > When the oscilloscope boots, the fan turns on and all the indicators
    > > on the front pannel light-on. But it hangs there. No keyboard response
    > > and nothing displayed on the screen. However, the screen is working,
    > > as when I turn off the device, sometimes I can see the beam on the
    > > display and some noise.

    >
    > > The indicators keep lighted on until you turn the oscilloscope off
    > > again.

    >
    > > Could anybody help me? Its a great oscilloscope, but it just does
    > > not work :-(

    >
    > > Juan

    >
    > I assume this is a DSO? Start with the simple stuff, check the power
    > supply voltages, see if the CPU clock is running, have a look at the
    > reset line, that should provide some insight.- Ocultar texto de la cita -
    >
    > - Mostrar texto de la cita -
     
    , Apr 17, 2007
    #3
  4. wrote:

    > Hello all,
    >
    > I recently purchased a broken 54520A hoping to be able to repair it.
    > The seller said that the screen was faulty. However, after the
    > oscilloscope arrived, I saw very soon that the problem was not the
    > screen but something else.
    >
    > When the oscilloscope boots, the fan turns on and all the indicators
    > on the front pannel light-on. But it hangs there. No keyboard response
    > and nothing displayed on the screen. However, the screen is working,
    > as when I turn off the device, sometimes I can see the beam on the
    > display and some noise.
    >
    > The indicators keep lighted on until you turn the oscilloscope off
    > again.
    >
    > Could anybody help me? Its a great oscilloscope, but it just does
    > not work :-(
    >
    > Juan


    Here are aso some experts to find:

    http://tech.groups.yahoo.com/group/hp_agilent_equipment/

    Jorgen
    dj0ud
     
    Jorgen Lund-Nielsen, Apr 18, 2007
    #4
  5. Guest

    Juan,

    There may be a lithium cell which is used to maintain the static ram
    where calibration data is stored. In the 5454x series of 'scopes the
    system locks up exactly as you describe when the lithium cell is
    discharged. This seems to happen about 15 years after manufacture.

    The service manual makes no mention of this problem!

    I had a similar problem with my HP 54542A 'scope and another poster
    had this problem with his HP 54540.

    Replacing the lithium cell and running the self-calibration fixed the
    problem for both of us.

    For more information, search this group (sci.electronics.repair) for
    "54540A".

    John
     
    , Apr 18, 2007
    #5
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