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
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.
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.
Hi Greg, did you saved the correction coefficients before you updated the firmware? 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. Massimo
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 iimetro.com.au
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 :)
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 flash. 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. Massimo
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.
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 them. 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. Massimo
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