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HP 8711A vector analyser boot problem

Discussion in 'Electronic Repair' started by gcd, Sep 26, 2006.

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  1. gcd

    gcd Guest

    I have an 8711A which 1/2 works.

    It passes boot self test, puts up the "initializing" message, progresses
    onto the analyser screen with menu but locks up and doesn't progress to the
    calculating coefficients message etc.

    Anyone come across this one before?

    I'd like to reflash the firmware but as it sees the same version on the
    floppy it won't flash it. This is a last ditch effort as it passes flash
    test so the CRC must be right.

    Passes the dram flash etc test, so it appears the basic fuinctions are OK,
    perhaps a dsp problem ? it does one sweep and then locks up, but it should
    have calculated coefficients before the sweep

    Anyone have any block diagrams of the CPU board?

    Thanks for any help

    gcd at
  2. Steve

    Steve Guest

    The HP 8711A is notorious for having backplane problems.
    Its a mechanical design issue where the boards can come
    loose, and the connectors become intermittent. Try re-seating
    all of the boards, especially the CPU board.

  3. Joerg

    Joerg Guest

    Hello Greg,

    I don't know this analyzer but FWIW here is what I found on our HP4191
    when it exhibited a very similar problem: They had used top notch
    (ceramic!) EMPROMs but then only furnished cheap sockets. Not the good
    stuff (milled) but the ones with tongues that I'd never even use on a
    prototype. I re-seated all EPROMs and the problem was gone.

    Much of this is online. But if the unit is older the scan might be too
    poor to see any details. Anyway, I'd check anything that is socketed.
    Hopefully the motherboard isn't one of those press-fit deals. Had to do
    quite a few soldering marathons on those.
  4. Max65

    Max65 Guest

    Hi Greg,
    did you saved the correction coefficients before you updated the
    It's absolutely needed to have the machine working the right way, that
    you write back them into the flash on the CPU board.
    The program flash aren't on sockets, they are directly soldered on the
    PCB. Only the bootrom (which is a flash device instead) is installed on
    a socket.
    Any single PCB component is checked at the bootstrap, so I guess that
    your problem isn't related to DSP or any other.
    Since I reverese engineered the machine for fun, (when you'll fix it),
    I can tell you how to convert the HP8711A to a fully functional HP8712A
    (the vectorial version, with the cable fault and IBASIC option too).
    You just need a 28F010 flash programmer and a little skill in patching
    that devices!
    Have a great day.
  5. gcd

    gcd Guest

    Hi all,
    thanks for the help offered by many.

    I've sorted the intial problem using an older version of the firmware.
    The unit came with A3.054 installed. I went back to A2.10 and the unit
    worked OK.

    Ended up being that the simm ram installed was 256kb 9 bit (which passed
    self test). A3.054 needed 2mb not 1/2 mb. I tried 9 bit simms as that's what
    was installed and they failed, ended up I needed to use 8 bit simms and all
    is OK

    I had started probing the dsp as the sweep tick didnt seem to be working and
    appeared to be linked to interrupt 5. Even thought I might have found a
    stuck at logic IC.

    Thanks to Caesar and Lachlan I was able to find the real source of the
    problem within minutes (rather than weeks!!)

    Massimo, reversing enginnering for fun... hmmmm..... not sure I'd call it
    that :) I much prefer having a schematic rather than try to work out what
    goes where, especially on this board as all the signal layers are middle
    layers with ground plane on top and bottom.

    I'd be very interested in knowing how to get the extra functionalilty,
    especially vector.
    if you'd prefer to contact me direct, rather than post here, the email is
    gcd A.T

    Was unable to save the CC data before reflashing due to the lock up it was
    expereincing, but not a huge problem. I've done most of a cal process on an
    8714B before, even made up one of the voltage references needed to do it.

    Have the facilities to burn flash and have hex edited a few files in my day

    Again thanks for the help offered by all

  6. Max65

    Max65 Guest

    Hi Greg,
    nice to read taht you fixed it.
    About the reverse engineering for fun, It's true.
    I'm just a radio ham, and I bought the 8711A form my hobby on e-bay
    just for $700.
    I fixed it (it had just a tantalum capacitor shorted on the CPU
    power!), but to do that I accessed the Agilent web site, where I read
    into a faq taht the 8712 and the 8711 are the same machine, just the
    firmware changes. When Dave Cunningham of Agilent supplied me the
    firmware update I wondered about it, because the same firmwares applies
    to all the models (8711,8712,8713 and 8714). So I said to myself; where
    is the trick?
    I found the answer into the 8711A service manual, where is explained
    how to change the CPU board. They say that you must keep the bootrom
    and install that on the new board!
    So, considering that the 28F10 is not a banked flash, and that you can
    install option via passwords into the service menu (about this try VGA
    and you'll get the VGA menu if you want to change the monitor, or try
    BEARS and you get the the K04 external switch box control menu), I
    thought that they have made a stacked configuration area into the
    I find it in the last 32*256bytes of the flash. The first machine
    configuration occupies the 32bytes with the higher address. The
    successive configuration is written in the previous 32bytes allowing up
    to 256 configs.
    I will send you the hex dump with the original and the modified config
    to achieve the phase mesurements (smith chart, phase, delay and polar
    formats) and the cable fault option.
    Have a great day.
  7. As an Agilent employee, it is always fun to see how folks get around
    some of these issues.

    Way back when the 8711 came out, nobody thought anyone would attempt to
    hack this, so the security was pretty simple (though not as simple as
    the 8753/8720 family.) This turned out to be a reasonable assumption
    since most larger companies that could afford to buy the 8711 were not
    about to waste time trying to hack something. Now that the 8711 has
    trickled down to the hobbyist's realm, there is a lot more hacking going
    on. As far as I'm concerned, I say go for it. We don't sell it
    anymore, so it is not hurting our business. I would much rather see the
    instruments in actual use, rather than being dumped.
    Disclaimer: this is MY opinion only; not Agilent's!

    Max65, I will accept your comment about the manual helping you figure
    out it's inner workings as a compliment. Most of that service manual
    was written by me, so I am glad it helped you.

    I believe there is actually a program somewhere that will reprogram the
    ROM to enable phase. The IBASIC option is also relatively simple to
    enable. This allows an 8711A to turn into an 8712A (a "non-existent"
    product). Likewise , it will turn an 8711B/C into an 8712B/C. However,
    phase information can always be extracted from any 871x product (via
    GPIB) regardless of whether or not it officially supported phase. This
    is because the entire 8711 family were Vector NAs. The 8711A/B/C and
    8713B/C just did not allow you to display phase, although it used phase
    for its correction algorithms. This was documented in the manual somewhere.

    Now, if any of you hobbyist want to hack our newer PNA series of
    analyzers, then I would get upset. However, hacking this family will
    not be easy due to its much higher level of encryption; it is no longer
    just a bit flip.

  8. Max65

    Max65 Guest

    Hi Caesar,
    I agree with all you say in your message. The reason I hacked the
    instrument is because it has been discontinued by Agilent. I will never
    buy a new vector analyzer for my hobby ( I don't have so much money to
    spend on it), and when I discovered that the 8711A have the phase
    discriminators, I supposed that it was a good deal for me to try to use
    I'm an industrial swr/fwr/hwr developer too, and I know that it's bad
    to hack the work of other people, because I know how many time it takes
    to do that, and the time is life, and life is the most most important
    thing for me. This is the reason I never try to hack anything which is
    still on the market.
    Anyway, when I did it on the 8711A I also informed Dave Cunningham form
    Agilent who told me how they are no more interest to that instrument
    (now they give for free the Intellution interface too).
    Caesar, I seen you second name: are your parents Italian?
    I had a college classmate with you surname.
    Sorry for my English.
    Have a great day.
  9. Lang


    Aug 14, 2009
    Hi Massimo,
    I would like to received your modified boot rom. (I own a 8711a analyzer)
    Many thanks in advance.
  10. apollo2mond


    Feb 6, 2010
    hp8711->hp8712, firmware patch

    Hi Massimo,
    i want to patch the firmware based on your hex file to make happen vector measurments, please guide me, many thanks apollo!
  11. apollo2mond


    Feb 6, 2010
    did you get the firmware pacth for hp8711a
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