Hi all,

?I am looking for the A5 Serial I/O PCB No. 08920-69129, and the A7 Controller PCB No. 08920-69107. My AF-Diags tell me they are faulty. All else seems OK.

Any comment or assistance would be appreciated.

Regards

Bill M.??? VK6IC

Hi Bill,

?? Amtronix Instruments has the A5, serial I/O board for $200. and the A7 Controller for $350. email ? lab5@...? if you're interested or need diagnostic help. Rick

Thanks Rick,

I suppose that's $US + Wads more for USPS.? Always a problem for OZ. We are more part of Asia, but most of their stuff is consumer quality.


I have been reading the manuals from IO Groups, in fact I have printed and bound them in two volumes plus the circuit diagrams separately.

I have done the power supplies re-cap and they are all trimmed and working fine. I have replaced the back-up battery on the memory boards

I actually have two 8920 test sets, one is 8921A, and the other is 8920A. The 8921A looks in the best condition, so I am concentrating on that. I did a bit of swapping and using RF-DIAGS and AF Diags. (great fun). I checked the +5 & -5V reference, that's OK. A9 Voltage is 5.072 on my 8022 Fluke meter. (The best I have).

RF-DIAG? went well up to the receiver test where is showed failures in AM & SSB Demod. I swapped the RX Module from the 8920a, and ran the tests again. Same result. so I suspect RX module is NOT really the fault. The spec an, CRO, and rf gen seems all Ok. The OXCO is spot on. So that is one item I will deal with .. works in progress (WIP).
On the AF-DIAGS I was able to determine which boards are suspect. The preliminary paths tests in AF-DIAGS is where the errors start. The first test, of af generators 1 & 2 run "No Failures".

The prelim AF Paths Test produces 9 failures!? and a code 511 (unable to determine failure). And on another run through, I had a Code 373. this pointed to the A4 Board being a high chance of being faulty.

Reading the specific diagnostic?descriptions Chapter 11 of the AF tests, Page 600 of the manual describes the Modulation Distribution Board functions during the tests. It seems to me that there is a switch that is stuck in the Source or the Monitor select Multiplexer, or both.? Mod Distribution Internal Test produced a Code 119.

So this is where I'm at.

My background is in Medical Electronics, CT, MRI, Ultrasound, Gamma Cameras .. etc.( ~30 years) I have a pretty complete workshop for electronic service, including SMC soldering. I am going to have a go at component level repair, if you could steer me to which chip to measure and prove as the culprit.

I have a Tektronics 2230 CRO and a Siemens, ancient but very stable, AF generator (level generator). One of my careers was as a scientific instrument maker, so I am old but no slouch (78 yo). So this project is for keeping the "grey cells" stirred.

Please help if you can.

Regards

Bill Macham ??? VK6IC

Millendon W.Aust.

618 9296 0137

Westwill1@...

Hi William,

It sounds like the problem is with one of your audio boards. I would swap the Audio analyzer #1, #2 and modulation distribution boards and see if your problems go away. We have a lot of those boards for?$50 - $70/ea. and discounts for multiple boards. The shipping to Australia could cost $50 or so.

Rick

Hi Rick,

Yes, it definitely looks like the Modulation Distribution Board is faulty. The label on the board says 08920-60409 with a sub number A-3308-10

The Serial I/O card on the 8920A is also proven faulty as I can swap it into the 8921A and can replicate the fault; swapping it back creates the fault on the 8920 again.

The A7 Controller is also faulty on the 8920A. That has the numbers, 08920-60307, Sub Number A3303-10.? The 8920A does not boot to "all Tests passed" but the screen is active and displays the following:-

" 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? ?(This did not fix the NO Boot problem)

So I may need the A7 Controller Board too.

In relation to the AFG1 & 2 boards, in all AF-Diags run,? the "AF Gen 1&2 Tests report no failures. They start to fail when doing Preliminary Paths test, which I understand involves the Modulation Distribution board. So I am inclined to try replacing the Mod Dist and the Serial I/O to get the 8921A working, and to replace the A7 board in the 8920A to get that to boot up.

It will be only then that I will be able to start Diagnostics and find any further problems.

So Rick this begs the question, what is it going to cost for the three boards including the P&P to my address:-

Controller Board

I/O Board

Modulation Distribution Board?

?

Regards

Bill Macham

31 Macham Road Millendon? 6056

?Western Australia.

Hi,
I'm in the UK and have a stash of boards almost certainly including those. I'd have to check exact numbers.

However I don't want to step on Rick's toes as he does so much to support 89xx users big and small. If Rick does not mind I can have a look at what I have.

Robert.

Hi Robert,

Many thanks for your interest in my problem.?

My ham call sign is VK6IC, although I was VK6II. That lapsed during a Covid problem at our Federal Comms office. I had the call since 1983.

I am 78 Years old and not yet ready to check out mentally, hence more ham radio and fiddling with good quality instruments. I am an Instrument maker by trade and spent over 30 years in medical and scientific servicing. Lots of fun.

I am now an aged pensioner, so cannot buy my way out of a problem. I mostly end up doing it the "hard way", time rich but money poor.

I value Rick's contribution and wealth of experience, plus his generosity to help,? The tyranny of distance features much in dealing with USA.

?

I look forward to your rumble through your stash. Maybe we will QSO when I get my HF Yagi up the tower. (works in progress, maybe this summer).

Regards

Bill Macham

?

?

Ahh ... I did not change the eeprom onto the other board. I have taken a snapshot of the eprom, some time back, into my win 7 computer via an eprom burner. Did a checksum after I did it on each, and it said the copy was OK. ??? I then burned another eprom with the data, and checked that as OK. I then put the original eproms back into the boards. At all times did I use an antistatic mat and earth myself and the burner, IE., did it very carefully.

I do not have any Memory drive cards for it and thought that I should take hard copies for some future event

I did both test sets and kept them labelled.

So the eprom that is suspect, is on board7 of the 8920A by the tests so far performed?

I will plug in the copied eprom? from the 8920A and see if it boots, or at least gives the LED codes at boot up.?

I guess the copy of the 8921A will not work if I plugged that in as a test?

Regards

Bill M

Millendon

?

Hi William,

The 8921 and 8920 have basically the same eeprom so they can be interchanged. We have had several cases of "non-recoverable firmware error" on boot up due to corrupt eeproms. I don't recall ever having that due to a defective controller board.

I also recommend you check the eeprom programmer to make sure it isn't "write protecting" the programmed eeprom. We have an eetools Chipmax that defaults to write protect the eeprom. The 8920 (21) writes to the eeprom every time you use it.

Rick

Thanks Rick,

Will do.

Bill M.

Hi Robert,

Has Rick mentioned any issue with your offer, directly to you ?

He is still assisting me with advice on eproms etc. I think we are not going to impact on his turf.?

I am not commercial, just an old codger doing what hams do. My stuff will go to the local ham radio club (NCRG) when I pass on.

I had a go at the gear yesterday and it definitely will require me to make some extender boards to fault find to component level. I will have to make them on my homebrew CNC machine. The connectors will be the difficult thing to make, so I may have to carefully unsolder ones from some sacrificial junk boards that are unrecoverable. I wondered if you might have such things in your stash, just to get the edge connector fittings off.? The HP 8920 has several lengths involved -- 40 pins on the Modulation Distribution Board. And I think that will fit one of the AF boards too.

Regards

Bill Macham??? VK6IC (westwill1@...)

No, nothing from Rick

I checked my workshop stash and I don't have those modules. I'l have to go to the storage unit and check there (I seem to be missing a box of modules, it's not where I thought it was). Apart from the distance it's been wet and windy recently and I don't like opening the unit in those conditions because once even a bit of damp gets in it's hard to dry it out again.
I'll look next time I'm there.

Robert.

Thanks Robert,

Just give me a shout when you get to it, If you do not find it, say in a month or so, please let me know .

I have the same trouble ... life time of "Accretions".

73s? Bill M.

Hi George,

I believe I have noted that information in the past but haven't thought about it in a long while. So far, I haven't seen "wide spread" cases of failed eeproms in 8920 units due to excessive read / write cycles. I'm thinking the read / write cycles would have to be really excessive to wear out the eeprom but haven't researched it.?

Rick

Hi All,

?? Feel free to help each other out with HP8920 boards. I have no resentment with helping out then people finding parts for less....Rick

Thanks Rab,

We are colleagues, not competitors.

I am still interested in your offer for boards, Robert has not got to rummage through his Stash, so the pace has slowed.

I am going a bit backwards with the 8921, I was swapping boards and the PSU smoked!!? No 5V, and the A9 board regulator was hot.?

I'll pulls all boards once I get the Psu working, and measure currents as I put them back in. It may be a foreign body fallen in the works and shorting the 5V line, or some Capacitor failed.

I am still having Fun and have lots of patience.

"I struggle on Rewardless"

Bill M.

开云体育

Hi William,

?? Sorry to hear that. I wonder if one of the plug in boards bent a connector on the motherboard and shorted it? Rick

Hi Rab,

I have recovered the 9821 to its former faults before the A10 PSU smoked,

I have discovered that my eprom blower has lots of bells and whistles, including the "Burn and leave unlocked".

I will revisit the copy of the working eprom from a known good board.

BTW, your advice that there was a bent pin was right on the money. Replaced Q3 on A9 and no more problems. (IRF-44 MOSFET)

MS _Diags gave all good voltages for the power system. RF all ok too except for the audio modulated tests AM SSB etc.

Very assuring to have a guru like yourself on these instruments.

?

Best regards

Bill M