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8921A PCBs required
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Hi John,
Thank you.
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Hmmm, I gotta say that I'm suspecting the processor board right now.
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Yes, if the blank 28C256 is attached, checksum error only pops out for the very first time. After that first boot, the checksum error is gone.
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Without recovery of CAL data, I think swapping processor board might be worthless.
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But I'll give it a try. I gonna buy a processor board to eliminate the last possibility. There are parts mules in the on-line market.
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Thank you again.
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James
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开云体育Hello,Friday, December 29, 2023, 10:31:48, chinesejames1990 wrote:
There is a lot of development programmers that have adjustable program and verify voltages (last one I used had it in programming method customization setup). But if programmer shows pin connection errors, first get a multimeter with a low voltage diode test mode and look if you can "see" ESD protection diodes between GND and VCC to each pin (maybe except Vpp). I had one plastic "windowless" one time programmable EPROM with a faulty pin wire welding, and it was successfully read in a cold state with a piece of ice in a small plastic bag on the top of chip. It worth trying (carefully) to extract data from this EEPROM, because otherwise whole unit became a set of spare boards, and most of them without cal data. -- Best regards, Yuri ? ? ? ? ? ? ? ? ? ? ? ? ?mailto:yuri@... |
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James,
It sounds like you may have a bad processor board ...not sure if that is what also damaged the EEPROM.? Still could be another issues ....second on my list is the memory board? which on the 8920A has the firmware and the NVRAM ( battery backed up ) Firmware should throw? a checksum error if it was bad or not reading correctly ...you already tried that and didn't have those errors anyway. If you put in a blank write enable EEPROM you will also see numerous checksum errors on the initial start for the calibration data but on the second boot that should be gone since default data was loaded in.? check in your programmer options that the EEPROM is software write enabled ....sometimes that is a setting you have to enable. If it was the EEPROM causing the initial error that should have fixed it ...the diagnostics will fail with the default calibration? data. At this point if you were in the US I would suggest sending it in for repair. The initial problem can be fixed and the calibration may be recoverable but it sounds doubtful at this point. Blown calibration data may turn the unit into parts since the effort to recover factory tuning may be more trouble than the unit is worth. Still has value as parts ...just not as much as if the calibration was good. |
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Thanks John,
Sorry for the late reply.
Yes, I gave it another shot these days.
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First, I put an empty new 28C256 on and turned on the unit; errors remained the same.
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Second, I used another programmer to read the original 28C256 and it couldn't even read it. The programmer popped errors about "bad lead connection" on some specific pins. The programmer is surely good.
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Well, maybe this is it. Got nothing more I can do. Maybe the unit is scrapped.
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Thanks again.
James
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开云体育Dear Yuri, ??? You could send us the 28C256 IC and we could evaluate it at
no charge. It's possible the IC is corrupt. We can read it and
transfer the data to another 28C256 and see if that works. You
could do that yourself with a prom programmer. You would need the
28C256 - we have many. What are the symptoms of the problem? Rick On 12/25/2023 3:44 AM, Yuri Ostry
wrote:
Hello, |
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开云体育Hello,Monday, December 18, 2023, 16:43:43, chinesejames1990 wrote:
If you have access to a programmer with valiable supply voltage, try to read your chip many times while decreasing supply voltage gradually, and write every read image separately. I had similar problem with Xicor X2816 chip in Marconi 2955, and finally I was able to generate correct image by analyzing files read from such "leaking" chip. If you are really lucky, you may find voltage at which chip will read almost stable with correct data (say 9 of 10 reads will be the same). It is same method that we used to recover "leaky" EPROMs in the past - IIRC, I already wrote here or in time-nuts list with more details. Regards, Yuri. -- Best regards, Yuri ? ? ? ? ? ? ? ? ? ? ? ? ?mailto:yuri@... |
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replacing the calibration data is going to be tough for the whole unit.? It will load defaults when it hits a checksum issue ...every section in the cal data has a checksum it's so important.? ?However these default values will often cause the unit to fail the RF diags in critical areas.? In a lot of areas the defaults are close enough but there are tuned circuits that need the modules specific data .
On some of the later cards the cal data was on the board ...see the service manual. May sure the EEPROM is SW write enabled ...there is a feature on those chips to disable the write besides the dip switch on the processor board. I have never seen an EEPROM fail completely ...usually only specific addresses will fail to verify. I would double check if you can with another programmer.? You really need that data which is why I mention backing it up. I have two very good IC programmer units that I use to cross check on issues like this. Make sure the IC is correctly aligned going back in as well .....on one of the processor boards ( A vs. B ) it seems like it goes in backwards. People always ask why I have so much test gear? and I usually go back to the old military saying " one is none, two is one and three is enough " Like I said you could put in a blank EEPROM as long as it is write enabled and the unit will load defaults? ...that should get you past the initial self test failure but the unit will probably fail the RF diags. |
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Hi all,
First, I'd like to thank all of you who gave me ideas and clues. So here is what I've done these days: 1. I ran the selftest program contained in the ROM, and I almost every error message popped out. 2. I checked the PSU supply rail and all the voltages were within criteria. 3. I think I found the smoking gun, that EEPROM 28C256 containing CAL data is broken: ? ? a) I used my programmer to read out the CAL data various times, but each time I read it the data file is different. (Using my BIN file comparator software, and the programmer (checked and it's in good working condition) ? ? b) I pressed and hold MEAS REST + Hz keys and power up the unit, so that all status could be reset as factory without affecting CAL data and ROM. I tried several times as well, but each time the screen displays this error message: "CAL DATA CHECKSUM FAILED; Default DATA is applied". Ummm not sure the exactly wording, but something like that.? ?(That screen is very hard to capture, it just blinks and is gone). ? ? c) I wrote all the BIN files read out from original 28C256 to new 28C256s one by one, and put the new 28C256 into the unit one by one, but got no luck; problem remains. 4. Bought 8 27E040 PROMS and rewrote the firmware using the BIN files downloaded from the FILES SECTION. Everything works good except the fault remains exactly the same. My guess is CAL data is broken due to faulty original EEPROM 28C256. And the worst thing is, I can't read it out in good shape nor can I re-calibrate the unit. Various selftest errors may be caused by bad CAL data. Is there any way to restore it, or any way to measure in order to re-calibrate the whole unit just like what factory did for people like us-individuals? Thanks in any advance! Regards, James |
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Thanks, John.
The battery is OK of 2.9V measured by my DMM.
Will try firmware update first.
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Regards,
James
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Hi John,
Thank you!
? ? ? ? ? ? ? ? ? John: First, try firmware update.
? ? ? ? ? ? ? ? ? John: Second, try to troubleshoot Processor board and SA board.
Roger that, I'll do above and let you know.
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I have downloaded EEPROM 28C256 contents by universal programmer.? What is weird is that I tried several times because sometimes the programmer failed to read out the EEPROM and said the chip is broken.? It finally completed after many tries.? And I'm sure my programmer is good because I bought a new 28C256 and that was without any trouble in writing and reading with this new 28C256.
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Thanks again for the kind advice.
Regards,
James?
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I found my former issues with my unit was good after repairing the PSU (bad Rica safety caps blew the switching circuit) and replacing the Memory Unit. It was causing a Non-Recoverable Firmware Error.
Of course during the course of my diagnosis some other faults were found and repaired, but that was what got me into the machine to start repairs. I haven't dug into what is faulty on the memory card yet, but I suspect bad Ram modules -- good in, garbage out kind of deal. Plus caps, caps everywhere! For the serial card, even the cheap eeprom readers can test the logic chips. I found both inverter chips bad, replaced them, and then that card worked again. I believe they were the 74ALS05A @ U11 and U5 |
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usually "Non recoverable Firmware Error" is a HW issue.
You can try and update the firmware on the 8920A's to a later version ...depends on the memory card you have installed but 18.X or 14.X IIRC. Doubt it will help but can't hurt. On the newer memory cards the ROM's are typically not erasable so you need a new set of 8 The only way to easily troubleshoot this error is with two units. My guess is that it's a processor board failure but it could be anything? ..second choice would be the SA board. Make sure you move over the EEPROM with the calibration data ....usually making a copy isn't a bad idea as well? |
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Hi William,
I met the exactly same problem! This HP8920A pops out that error message every time when I'm trying to get into Spec Ana screen: " Non recoverable Firmware Error" the two lines below read * $ header: Syshlp.c,v 22.1 96/06/20 21:43:17 hmgr EXP$, at line number 273 To continue operation Power Off and Back On" |
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Hi William,
toggle quoted message
Show quoted text
?? I just sent you an email from my gmail account. Hopefully, you will get that one. Thanks ! Rick On 8/30/2023 7:53 PM, William Macham via groups.io wrote:
No Rick, Not a word. I have been expecting your QSO. |
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No Rick, Not a word. I have been expecting your QSO.
I was thinking of Fires in USA and dire circumstances you may be in. Glad to hear from you. Maybe My Anti Virus settings are a bit fierce ?! .. Anyway, It seems we are "On the same Page Now". ... DX is now open. Are you able to Make it happen? Regards Bill M. |
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开云体育Hi William, ??? I'm still here. I've sent several messages to:
westwill1@...???????? Did you get any messages from me?
Rick
On 8/28/2023 7:24 PM, William Macham via groups.io wrote:
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