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Keithley 197 troubleshooting

Discussion in 'Electronic Equipment' started by Dan Lenski, Mar 13, 2007.

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  1. Dan Lenski

    Dan Lenski Guest

    Hi all,
    I have a disabled Keithley 197 DMM. This is an older model, but it
    has a nice GPIB interface, so I'd like to get it working.

    When turned on, it displays the message "cErr". According to the
    manual (http://www.tnw.utwente.nl/onderwijs/practica/doc/app/
    keithley197.pdf) this means that there's a problem with the NVRAM that
    stores the calibration data. I've tried bypassing this error by
    pressing the buttons as recommended on page 5-9 of the manual, however
    the cErr reappears.

    The NVRAM chip is a little 8-pin DIP chip apparently. I'm having
    trouble identifying it. It's labeled:

    X2443P
    8432ES

    Anybody know what this chip is, or can give me any other advice in
    getting this DMM working? Thanks,

    Dan
     
  2. DaveM

    DaveM Guest

    The X2443P is a Xicor NMOS nonvolatile static RAM, 16 bits X 16 words, tristate,
    750ns, Vcc = 5V

    I searched briefly for anything that would be a good sub for it, but came up
    empty. Maybe you can do better.
    --
    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
    address)

    Life is like a roll of toilet paper; the closer to the end, the faster it goes.
     
  3. DaveM

    DaveM Guest

    I forgot to mention that the X2443 is a serial 16x16 RAM.
    I did happen to find one web site that lists the X2443 in stock
    (http://www.acecomponents.com/) but no price, so you're at their mercy.

    Cheers!!
     
  4. Dan Lenski

    Dan Lenski Guest

    Thank you, Dave! Sounds like it's a pretty obsolete part :) Maybe
    someone makes a pin-compatible serial RAM in a larger size?

    I think I'll do the other tests on the device to make sure everything
    else is working, then try to track down this part.

    By the way, how'd you find out what it is? Alldatasheet.com and
    Google weren't much help to me.

    Dan
     
  5. DaveM

    DaveM Guest


    I found it at http://www.datasheetarchive.com. That's the only datasheet web
    site that even came close, but still no complete datasheet; just a list of basic
    specs.
    Not even a pinout...

    Cheers!!!

    --
    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
    address)

    Life is like a roll of toilet paper; the closer to the end, the faster it goes.
     
  6. Guest

    We scanned several Xicor data books for our datasheet site but didn't
    realize they were scanned at the wrong resolution. The books were sent
    for recycling before we realized. This is one of those scans which
    gives some detail on X2443.

    It's almost unreadable but here it is anyhow.

    http://www.datasheetarchive.com/x2443.pdf
    http://www.datasheetarchive.com/x2443.jpg

    Regards
    DatasheetArchive.com
     
  7. DaveM

    DaveM Guest


    Thanks for the follow-up!!! Very kind of you to post those pages. Databooks
    going to a recycler!!!!???? ACKKKKKK!!!!!!!!!!!!!!!

    --
    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
    address)

    Life is like a roll of toilet paper; the closer to the end, the faster it goes.
     
  8. carneyke

    carneyke Guest

    Perhaps it needs to be calibrated and the error will disappear.
     
  9. Dan Lenski

    Dan Lenski Guest

    Yeah, I've tried to go through the calibration procedure but it won't
    go into it... as soon as it begins it puts up the "cErr" message. I
    think this means the NVRAM is actually dead, not just blanked.

    Dan
     
  10. carneyke

    carneyke Guest

    Dan,
    I still think it needs calibration. Does the unit have a rear panel
    cal enable switch or an internal jumper for cal enable. You need a
    manual if you don't have one. Keithley website may have a downloadable
    version. When you power up and get the "cErr", press one of the soft
    keys (rel, db, sto or rcl). That will bypass the error and let it
    operate with a flashing "c" indicating cal constants lost. The manual
    i have indicates different cal procedures for the different firmware
    versions. You need a manual. BTW the soft keys (previously mentioned)
    need cleaning or they don't makle contact. Good Luck, Kevin
     
  11. Dan Lenski

    Dan Lenski Guest

    Kevin, thanks for the tips. I do have the manual, and have tried
    this. Unfortunately, when I press one of the soft keys it flashes all
    zeroes (like when just turned on), and then returns to the cErr
    message in about 0.5 seconds.

    The manual doesn't say what to do in this case, although it says to
    try replacing the NVRAM IC if the cErr persists...

    Dan
     
  12. carneyke

    carneyke Guest

    Damn it's a good meter too, lots of digits. If you really need it,
    Keithley always provided good service at reasonable rates. I don't
    know if they will service that model. I have a Keithley 197 on my
    bench at work. I keep it for the min-max function to "trap"
    intermittent problems. Good Luck, Kevin
     
  13. Peter Matler

    Peter Matler Guest

    And, they do sell parts...
    Peter
     
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