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HP 3310B Malfunction Generator

Discussion in 'Electronic Equipment' started by rickman, Jan 26, 2013.

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  1. rickman

    rickman Guest

    I bought this thing some 10 years ago used and it has worked ok, mainly
    as an audio generator. I fired it up the other day and the upper ranges
    seem to output a funky sine wave now. The 10 kHz and 100 kHz ranges
    output a distorted waveform that does a direction reversal a little bit
    after going negative of the midpoint. It almost looks like a rectified
    sine wave, but the waveform is more than half a cycle. I don't see any
    issues on the other waveforms.

    I can play with the range switch and find that turning it slowly can
    have an impact on the point of the waveform where the reversal occurs.
    But it doesn't really feel like a switch problem. I would disassemble
    the switch to see if there are mechanical issues, but it is one of those
    multi-gang wafer switches with components mounted directly on it and
    each gang is soldered to the board, a real nightmare to remove. This
    thing was made to never break, not to be repaired.

    I don't have any info on it. The circuit board has some dozens of
    transistors, a couple of what are likely op amps (metal cans) and well
    over a hundred passives. I don't know where to begin trying to fix
    it... other than connectors and switches are the primary point of
    failure. But even removing and reseating boards looks like a bear in
    this thing.

    Any suggestions on ways to repair this?

    I saw the other thread on new units and had looked at some of the little
    $8 boards on eBay. Funny that there isn't much in between the $8 boards
    and the $400 boxes. I would have thought this is something that could
    be done very inexpensively these days. I would use a PC audio output
    but my signal is outside the 20 kHz upper limit of audio outputs.

    Maybe I'll add a simple sig-gen to the prototype circuit I'm building.
    Lots more than $8 of effort, but I'll know what I'm getting.

    Rick
     
  2. Jamie

    Jamie Guest


    Caps..and power supply.

    Jamie
     
  3. tm

    tm Guest

    Service manual here:

    http://www.home.agilent.com/agilent...o&pageMode=OV&pid=3310B:epsg:pro&cc=US&lc=eng

    As always, check the power supplies first.

    Then RTFM
     
  4. Tim Williams

    Tim Williams Guest

    Not knowing the 3310 offhand, I thought for a moment you were talking
    about a piece of test equipment which intentionally generated malfunctions
    for testing purposes.

    Hey, it's HP, who knows what kind of stuff they made!...

    Tim
     
  5. WoolyBully

    WoolyBully Guest

    That is kinda funny.

    Except for the top post.
     
  6. rickman

    rickman Guest


    Lol!

    I don't care if you top post, but in this case your sig made all of my
    post disappear... even better, I didn't have to snip! I'll try top
    posting in some of the idiot threads that are so popular here. That
    should encourage others to trim a bit... lol

    Rick
     
  7. rickman

    rickman Guest

    Thanks. I'll take a look at it. I guess I'm just intimidated by the
    disassembly job alone.

    It doesn't really look like a PSU issue to me. I would suspect the
    switches, but when I work them it just doesn't feel like that's the
    problem. The unit has tons of test points so that should make it easier
    to see what is going on.

    Rick
     
  8. Jamie

    Jamie Guest

    I am not sure the age of that unit but I hope it's newer than the tube
    era :) A LCR meter would serve you will, along with a DMM.

    Oh, and lets us not for get to use a scope on the power supply for cap
    ripples and possible linkage in selenium devices and maybe germanium.

    Jamie
     
  9. Robert Baer

    Robert Baer Guest

    I have an HP 3312A Function Generator, and the manual.
    The looks are quite different, but the general operation should be
    very similar.
    Basically, it starts with a triangle / square generator,and the sine
    is created with a DFG from the triangle.
    So,your sine waveform problem is due to a bad diode or resistor in
    the diode / resistor chain on the polarity side where you see the defect.
    I could scan and send diagrams as need.
     
  10. Robert Baer

    Robert Baer Guest

    I have an HP 3312A Function Generator, and the manual.
    The looks are quite different, but the general operation should be
    very similar.
    Basically, it starts with a triangle / square generator,and the sine
    is created with a DFG from the triangle.
    So,your sine waveform problem is due to a bad diode or resistor in
    the diode / resistor chain on the polarity side where you see the defect.
    I could scan and send diagrams as need.
     
  11. Robert Baer

    Robert Baer Guest

  12. Robert Baer

    Robert Baer Guest

    Reminds me of the Missing Pulse Generator used in the Nike/Ajax
    missle test van....
     
  13. tm

    tm Guest

    So you would not recommend first checking the power supplies on a 40+ year
    piece of test equipment before doing any follow-up trouble shooting? Even
    when it is a well known fact that electrolytic capacitors that old are often
    found degraded.

    Oh well, whatever.
     
  14. rickman

    rickman Guest

    Hey, that is one of the "rules of thumb" for repairing any circuit fault
    in my opinion. First check the supplies, then if a digital circuit,
    check the clocks. They are fast, easy checks to make.

    I think Robert is saying he has some insight into the failure based on
    the symptoms, so maybe the PSU can be skipped this time. I will be
    looking at the manual I download and if it has good info on the test
    points, I'll be checking the power supplies.

    Thanks,

    Rick
     
  15. rickman

    rickman Guest

    Oh, how long has it been missing?

    lol

    Rick
     
  16. Tim Williams

    Tim Williams Guest

    That's the spirit! ;-)

    Plus it's nice if you're just slapping something on which isn't very
    relevant to quoted material. Saves time, makes it easy to read.

    Tim
     
  17. Robert Baer

    Robert Baer Guest

    I did NOT say that; i mentioned where the problem was most likely to
    be found.
    Yes, it is possible that there may be one or two degraded
    'lytics..even the old wet electrolytics lasted 20 years at best and even
    then many could be recovered by adding electrolyte.
    On old tube equipment, powering them up with a variac at zero and s l
    o w l y raising the line voltage to full will allow most of degraded
    'lytics to re-form and perform adequately at worst.
     
  18. rickman

    rickman Guest

    Ok, I'll bite, who is Maynard Philbrick? I thought the name was
    familiar, but googling it doesn't provide anything useful, mainly
    genealogy pages. I can't even seem to exclude them they are so
    pervasive. Linking the name to HP doesn't do it either.

    The name does sound familiar. Is that a name here?

    I've mainly worked on digital stuff including state of the art (at the
    time of course) floating point array processors. Analog is not my
    forte, but I'm comfortable with it.

    It seems I am spending more time getting a new lab setup than actually
    working on anything. I cleared out some old appliances and now have
    room for an 8 foot workbench which I plan to build. But before I do
    that I am turning my hand router and hand saw into table tools to help
    with the workbench construction. The test gear is the same way, I need
    this to fix that and before I can use that I need this other thing...
    I've let things slide too long.

    Wasn't it Lincoln who said, "Give me six hours to chop down a tree and I
    will spend the first four sharpening the axe"?

    I'd prefer to use a chain saw...

    Rick
     
  19. tm

    tm Guest

    OK then. Sorry for the comment. I miss-understood what you were implying.
    And agree with your assessment.
     
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