Author Topic: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)  (Read 59635 times)

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Offline m k

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #425 on: November 13, 2021, 04:01:36 pm »
You can quite easily trace _reset backwards but you most likely need an extender board.

SilverSolder has all kind of exotic extras, maybe he can spare an extender.

If you find one I'll probably need it after you so don't let it go.
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(plus lesser brands from the work shop of the world)
 

Offline SilverSolderTopic starter

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #426 on: November 14, 2021, 02:55:44 am »
Hi folks,

I now have a 8506A and a 8505A kind of working.
The 8505 with RMS, ohms and current, the 8506 with ohms. Both instruments with GPIB.
I also bought some spare cards for the future.
The 8505 has software version 5.01 and the 8506 has 6.05
Both instruments have the same issue, the reset procedure at boot restarts continously. If I press and hold the reset button on the frontpanel the instruments will come out of the reset cycle and work normaly.
I have started to recap the instruments, but still work to do.

Mikael, Sweden

I have seen those kinds of issues (weird behaviour, or outright refusal to boot) when the EPROM is "weak", i.e. made by a programmer that is not up to the task.  Maybe as a first experiment, try to re-seat the EPROMs on the processor board...

The latest known firmware releases are 5.0.6 for the 8505A,  and 6.0.7 for the 8506A.


 

Offline 1audio

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #427 on: November 14, 2021, 06:32:39 am »
Does the eprom have firmware or just the cal constants? I have 2 8506A's now and I'm wondering if I should replace the eproms as a preventative.
 

Offline SilverSolderTopic starter

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #428 on: November 14, 2021, 02:53:58 pm »
Does the eprom have firmware or just the cal constants? I have 2 8506A's now and I'm wondering if I should replace the eproms as a preventative.

The EEPROM only has cal constants.  The firmware is in a separate pair of EPROMs.
 

Offline Neptuni

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #429 on: November 15, 2021, 06:22:25 pm »
Hi,

The 8505 is ok now after removing and insertion of the IEEE and isolator card.
The 8506 is still rebooting…

Are there someone who could assist burning two sets of EPROM (for my 8505A and 8506A), it would be nice to have the latest firmware in my instruments, but I dont have access to equipment? I would if course pay for expensises and shipping.

Mikael
 

Offline Neptuni

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #430 on: November 15, 2021, 07:26:00 pm »
Found someone in Sweden that sells and burn eproms, so now a set is on the way in the post.
 
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Offline garrettm

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #431 on: November 17, 2021, 05:24:13 am »
Hi,

The 8505 is ok now after removing and insertion of the IEEE and isolator card.
The 8506 is still rebooting…

[...]

Mikael

It sounds like the microcontroller isn't getting stable power during turn on. I had a unit that would exhibit similar behavior due to the 5V supply being too low and a bad capacitor.

Check the +5V power supply (unguarded Vcc) at the Controller module (using test points TP1 and TP3) or at the PSU (this method does not account for voltage drop to the Controller). If it's in spec (5.05 +- 0.05 V), check the electrolytic caps on the Controller board. If those are okay, try raising the voltage a little bit higher, say 5.1V.

Good luck with the firmware upgrade, I'm happy to see people using the bins I uploaded. That said, I doubt you will notice much--if any--difference in operation of the DMM using the new FW unless you are controlling the meter remotely. I've never seen a unit with 5.01 FW out in the wild. Your 8505A has the oldest FW I have ever seen for an 850xA. If you're willing, I would love to see photos of the DC Signal Conditioner module for comparison. Fluke revised the DC Signal Conditioner multiple times, and I'm curious to see what one of the earliest iterations looked like.
« Last Edit: November 17, 2021, 05:29:27 am by garrettm »
 

Offline m k

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #432 on: November 17, 2021, 10:33:35 am »
It seems that somebody has read xDevs repair story since ebay was full of .156 spaced edge connectors.
Thoug Vectorbord 3682 was best for the riser part I found, ready made HP extenders were also available but not very decently priced.
But there is also an arcade world and they have a JAMMA adapter and it has .156 spacing, clean fingerboards are also available.

So next idea for empty controller slot, a sniffer board.
Nowadays an MCU can fit in empty space of skeleton type of DIL-socket, quite fast and easily implemented serial buses are also available.
So the operation of a sniffer is mainly in the extra controller slot and from there a shielded serial cable connects to CPU riser of the main controller board.
It can easily be also a concept and so implemented anywhere.

Full software simulator implementation of a meter seems to be pretty irritable, occacionally.
(personal opinion)
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 

Offline Neptuni

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #433 on: November 17, 2021, 06:29:58 pm »
Hi again,

One set of EPROMS received today and now I have the 8505A working with 5.05 fw:)
Yes, both 8505a and 8506a will be used with GPIB, so thanks for the files!
I will look at the power supply and also the caps on the controller as well, the reboot has came back…

I can post a picture on the conditioner board later.
 

Offline garrettm

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #434 on: November 17, 2021, 09:31:16 pm »
Hi again,

One set of EPROMS received today and now I have the 8505A working with 5.05 fw:)
Yes, both 8505a and 8506a will be used with GPIB, so thanks for the files!
I will look at the power supply and also the caps on the controller as well, the reboot has came back…

I can post a picture on the conditioner board later.

Are you sure your new EPROMs have 5.0.5? 5.0.6 is the newest FW for the 8505A and 6.0.7 for the 8506A (though CT models use different FW, newest IIRC is 1.0.1).

For future reference, an inexpensive programmer like the XGecu TL866II Plus will work with lower voltage UV EPROMs such as the M2764A. That said, it might still be cheaper to pay someone else to program them if this is a one-time job. I've found it helpful to have a programmer on hand, that way I can read chips and upload FW for others to use, test ICs (e.g. 7400 series), as well as programming ROMs. For 35 USD, I feel I've gotten my money's worth out of the TL866II.
« Last Edit: November 17, 2021, 09:45:22 pm by garrettm »
 

Offline Neptuni

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #435 on: November 17, 2021, 10:11:17 pm »
Correct, 5.06 is the new version. Thought about getting a programmer, but maybe later on.
 

Offline m k

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It seems that somebody has read xDevs repair story since ebay was full of .156 spaced edge connectors.

Some reading comprehension again.

My modules are not .156 spaced, they are .150 spaced.
(or so I've measured several times)
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 

Offline SilverSolderTopic starter

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Correct, 5.06 is the new version. Thought about getting a programmer, but maybe later on.

I ran into a lot of issues with high voltage EPROMs, I ended up getting a baby Batronix programmer just for those.   The TL866 type programmer works great, but couldn't cope with the high voltage chips...  the chips ended up with "weak bits" that caused unpredictable behaviour in the controller.  Took me a while to figure that one out, as you can imagine!  :D
 

Offline m k

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Somebody should explain those extra connections of P12 and P13.
In place somewhere else?

My DC Sgn Cond has a clear hole and metal edge of half of 4th pair of P12.
Current Shunts has also a metal edge but AC RMS has not, AC RMS also has a slim 3rd connection of P13.
Ohms has no hole nor metal edge or extra P13 stuff.

Current Shunts has also some metal case close calls.
Should I move or insulate it?
« Last Edit: January 04, 2022, 03:41:43 pm by m k »
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 

Offline dietert1

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #439 on: February 19, 2022, 04:11:03 pm »
Today i got an image similar to the first post of this thread. We have two meters HP 3478A and a Keithley 2700, acquired some days ago. Both never calibrated by us. Image shows todays check/comparison measuring a 2x5 LM399 array i made some months ago.
- The 3478A with green DIY backlight
- The 2700 delivered a "Benchkit 2000" to a Keithley 2182A

Regards, Dieter
« Last Edit: February 19, 2022, 05:29:56 pm by dietert1 »
 
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Offline Dave Wise

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #440 on: December 18, 2022, 02:47:12 am »
It says 'HI 5.0.4' on power up.  Is that the firmware version?

Yes, and - the evidence so far - indicates that version number starting with 5 means 8505A, starting with 6 means 8506A.

Skimming the rest of the thread I didn't see anyone revisit this.  I just wanted to say, the first thing popped into my head was "Hardware Interface".  I wouldn't be surprised if power-up code probed the hardware to determine what model instrument it was running on.

FWIW,
Dave Wise
I did a lot of 8080 assembly-language programming in the early 1980's, working at Tektronix developing firmware for the 4025 and 4027 Graphics Terminals.  If you ever displayed a pie chart, you can thank me for the polygon fill code.  You wouldn't believe how many corner cases I had to work around to avoid crashing.
 
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Online joeqsmith

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #441 on: December 18, 2022, 04:13:45 pm »
It says 'HI 5.0.4' on power up.  Is that the firmware version?

Yes, and - the evidence so far - indicates that version number starting with 5 means 8505A, starting with 6 means 8506A.

Skimming the rest of the thread I didn't see anyone revisit this.  I just wanted to say, the first thing popped into my head was "Hardware Interface".  I wouldn't be surprised if power-up code probed the hardware to determine what model instrument it was running on.




Quote
        Online SilverSolder
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          Re: Old school 8080 EPROM disassembly - is it making sense?
          <https://www.eevblog.com/forum/microcontrollers/old-school-8080-eprom-disassembly-is-it-making-sense/msg3455878/#msg3455878>


« *Reply #26 on:* February 09, 2021, 04:15:08 pm »
Attached disassembly listing from the Ghidra tool.

I still can't get over how comprehensive it is.  It knew about the reset
jump table without being told, too.

We know that the absolutely first thing this instrument does when it
starts, is

1) Somehow it figures out which hardware it is running in - this code is
used in two different models of the instrument

2) Depending on what hardware was identified, it will display one of the
two strings below in the LED display (ignore spaces in front):
       HI - 5.0.6
       HI - 6.0.7

Offline Dave Wise

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #442 on: December 18, 2022, 04:38:07 pm »
Do you think it stands for Hardware Interface, or just "Hi there"?
 

Online joeqsmith

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #443 on: December 18, 2022, 04:42:07 pm »
I don't think it matters

Offline bdunham7

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #444 on: December 18, 2022, 05:50:26 pm »
The design of the 850xA controllers evolved over the lifecycle of the instrument and I think the size of available EEPROMs went up quite dramatically over that time.  I've attached a photo of the EEPROMs from a single-board controller from an 8506A, not a particularly late version.  It has both 5.0.3 and 6.0.4, so obviously the EEPROMs have software for both models.  Up until 5 minutes ago I would have told you that the hardware determination must be somewhere on the controller itself--IOW the EEPROMs may be shared, but the controllers were not interchangeable between models.  I would have thought that because AFAIK the part numbers are different between the models. 

However, when I plug this controller into a mostly empty 8502A chassis, the display comes up "HI 5.0.3" before it goes to "ERROR".  If I plug it into an 8506A with the isolator removed, it comes up "HI 6.0.4" then "ERROR".  With the isolator removed it can't see the remaining modules, so it isn't the presence or absence of the Thermal RMS module that is doing it. I didn't try it in my 8505A because it is all buttoned up and calibrated.  So there is something on the mainboard in the unguarded bus, not in the controller, that determines this.  My 8506A wiring diagrams aren't great and I haven't found where it is.  I suppose it could be in the front panel assembly?

A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline Dave Wise

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #445 on: December 18, 2022, 06:42:32 pm »
<pedantic> EPROM, not EEPROM.</p>  The latter wasn't really a thing yet, and anyway is small capacity.

In some of today's computers, BIOS reads a few GPIO lines to identify the board.  The lines are grounded or pulled to Vcc according to board-unique manufacturing "stuff options".  Evidently Fluke did this too, with a bit somewhere in the chassis or front panel to distinguish between models.  Dust off your MDS-80 and trace the power-up code as it executes.

Dave Wise
Hardware/Software Engineer
Tektronix, Information Display, 1980-1994
Phoenix Technologies, 1996-2022
 

Offline bdunham7

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #446 on: December 18, 2022, 08:02:57 pm »
Here are the front panel logic sections that would be involved.  Can you spot the difference(s)?  I haven't yet...

A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline SilverSolderTopic starter

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #447 on: December 18, 2022, 08:55:20 pm »
Here are the front panel logic sections that would be involved.  Can you spot the difference(s)?  I haven't yet...


They are identical (I overlaid them in Photoshop).
 
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Offline bdunham7

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #448 on: December 18, 2022, 09:05:33 pm »
Well then, how does it know the difference?  I suppose there could be something elsewhere, like in the switch scanning circuitry.  The 8506A is a bit of an afterthought kludge in some ways, so I assume they just put something in somewhere for the code to look at in this specific instance.  That's why the controller IDed as 5.0.3 in an entirely wrong unit--that's the default and it only goes to 6.0.4 if it sees that 'something' that we don't know about.

Edit:  Well, the front panel diagram in my 8506A manual is labeled 8505A and appears to only have the switch/light labels for that.  The one in my 8505A manual actually has a flag and some alternate diagrams for the 8506A, but is missing a large part of the front panel switch section.    |O
« Last Edit: December 18, 2022, 09:27:59 pm by bdunham7 »
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline m k

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Re: Some old school instruments showing how it's done (HP 3325A and Fluke 8506a)
« Reply #449 on: December 18, 2022, 09:19:02 pm »
Heh,
SilverSolder educated me once.

tip,
don't be narrow minded.
Advance-Aneng-Appa-AVO-Beckman-Danbridge-Data Tech-Fluke-General Radio-H. W. Sullivan-Heathkit-HP-Kaise-Kyoritsu-Leeds & Northrup-Mastech-OR-X-REO-Simpson-Sinclair-Tektronix-Tokyo Rikosha-Topward-Triplett-Tritron-YFE
(plus lesser brands from the work shop of the world)
 


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