project: extending HP3478A functionality

[kirill_ka]

BTW, you may want to replace this cap.
I've had caps like that fail and leak nasty stuff all over the board. IIRC they're known for doing that.

Thank you. I will definitely replace it. I didn't think they are so badly behaved.

[kirill_ka]

A quick video demonstration.
 
https://drive.google.com/open?id=179wN6CET8ZQY1wQDYIMmN7-N4oslAw8C

[The Soulman]

  Now you should write a new manual for it. 
Well done.

[babysitter]

Thank you for pointing out this little bugger. After having 2 machines blowing their tar last year, I am in the process of exchanging all RIFAs I find. 2 Devices are clear now, with the 3478A its 3 waiting now.

[kirill_ka]

Thank you for pointing out this little bugger.

There are 4 of them. I think 2 big ones (0.022uF) are not that dangerous, because they are connected across the switch.
But the other two 1000pF are across mains.

[kelchm]

There are 4 of them. I think 2 big ones (0.022uF) are not that dangerous, because they are connected across the switch.
But the other two 1000pF are across mains.

Are you maybe thinking of another meter? I just took a look at my notes from when I tore down my two 3478A's and I didn't note down seeing any 1000pF caps. Did I miss something?

Here's what I noted down as caps that I will replace eventually:

S/N 2619A48043

Location	Capacitance	Voltage	Brand	Notes / Other Markings
C761	3300µF	25V	SMC	8827(2) (M)85ºC
C702	330µF	50V	SMC	88 C(2) (M)85ºC
C703	330µF	50V	SMC	88 C(2) (M)85ºC
C711	1000µF	25V	SMC	8835(2) (M)85ºC
C765	0.022µF	250V	RIFA	Photo
C766	0.022µF	250V	RIFA	See Above

S/N 2619A39329

Location	Capacitance	Voltage	Brand	Notes / Other Markings
C761	3300µF	25V	SMC	8827(2) (M)85ºC
C702	330µF	50V	Sprague	8742(M) 85ºC
C703	330µF	50V	Sprague	8742(M) 85ºC
C711	1000µF	25V	SMC	8831(2) (M)85ºC
C765	0.022µF	250V	RIFA	Photo
C766	0.022µF	250V	RIFA	See Above

[kelchm]

A quick video demonstration.
 
https://drive.google.com/open?id=179wN6CET8ZQY1wQDYIMmN7-N4oslAw8C

This is awesome!

I've starred your repository and plan on experimenting with this at some point in the future.

[kirill_ka]

Are you maybe thinking of another meter? I just took a look at my notes from when I tore down my two 3478A's and I didn't note down seeing any 1000pF caps. Did I miss something?

Those are A1C721 and A1C720. I have an old version of 3478A. Maybe they where changed in newer revisions.

[kirill_ka]

I've starred your repository and plan on experimenting with this at some point in the future.

You are welcome

[kelchm]

Are you maybe thinking of another meter? I just took a look at my notes from when I tore down my two 3478A's and I didn't note down seeing any 1000pF caps. Did I miss something?

Those are A1C721 and A1C720. I have an old version of 3478A. Maybe they where changed in newer revisions.

Thanks, I took another look and was able to locate them. They are directly between the transformer and the mains input. Removing the GPIB ribbon cable makes them easier to see.

[bitseeker]

Thanks for the photo. I should check that, too.

[kirill_ka]

The software part works quite well. So I'm going to use it for some time to see what I want do next.

I've been using my "extended" HP3478 for awhile now. All the features work very well.  Now I'm asking for an advice on what else to do about this project. Probably I should add some documentation to make it easy to reproduce? I feel a bit uncomfortable about I'm the only one using such a cool thing

[bitseeker]

Implementation and operation guides so others could build and operate it would certainly be good things to have to make a more complete package.

[kirill_ka]

At last there is some progress with the documentation. Since I've been experimenting with HP8561e, I revised GPIB command line and wrote a command line reference.
https://kirill-ka.github.io/hp3478ext/
Also there's a basic implementation guide, and pre-compiled firmware.
Any suggestions, comments are very welcome.  I'm not comfortable writing manuals in English, so the text is probably awkward. I would be happy if someone help me to improve it.

[bitseeker]

Thanks kirill. Can you send me the LibreOffice Writer files? It's more efficient making corrections that way rather than have you re-enter them from a list of changes.

[kirill_ka]

Thanks kirill. Can you send me the LibreOffice Writer files? It's more efficient making corrections that way rather than have you re-enter them from a list of changes.

I just uploaded them to the git. Thanks.
https://github.com/KIrill-ka/hp3478ext/blob/master/ug1-gpib-commands.odt?raw=true
https://github.com/KIrill-ka/hp3478ext/blob/master/ig1-basic.odt?raw=true

[bitseeker]

Pull request submitted. I clicked a bit too fast and may have borked it. Let me know.

[kirill_ka]

Pull request submitted. I clicked a bit too fast and may have borked it. Let me know.

bitseeker, thank you for spending your time on this. It's a very valuable experience to me.  I had to revert some spacing changes, because html and odt don't look the same. If you add empty lines in odt to make it better, html becomes too sparse. Tabs also behave differently.

[bitseeker]

Ah, OK. I should've checked that. I haven't used word processors for HTML, so I only paid attention to the way it looked in its native form. I hope it wasn't too much of a hassle to revert the spacing. I enabled tracking for all the edits in the hopes it would minimize the effort to remove any changes that you didn't want.

Once you're done with any additional info for the docs, I can take a final pass over the text (I'll leave the spacing alone).

[kirill_ka]

I think I'm done with it for now. So, you are welcome to take a look.  I tried to clarify the description of the OX command and added a small section on the stand-alone HP3478A operation. There should be no changes apart from that.

Meanwhile I wrote a basic Tcl library for remote programming. I'll publish it and also some Tk GUI examples as soon as I have enough play with it.

[bitseeker]

OK, I'll check it out when I get home.

[bitseeker]

That new paragraph describing the standalone extension mode helps a lot. I just made a few corrections to touch it up and created a pull request for you.

Cheers!

[Miti]

Hi Kirill,

I tried your project on my HP3478A and it doesn't do anything when I press SRQ. Can you check the fuses configuration on the Atmega? I've checked the connections twice.

Thanks,
Miti

Edit: I'm not using the USB to serial adapter. I understand that part is optional if you want to send commands to the meter, or am I missing something? Should it work only with the mini pro?

[kirill_ka]

Hi Miti,

It definitely works without an USB-to-UART adapter, but it would be very hard to diagnose any problems without one.
How did you download the firmware then?
The "standard" fuse settings used on those atmega328p boards should work.
However the recommended efuse configuration is at the bottom of the following page:
https://kirill-ka.github.io/hp3478ext/basic-impl.html

[kirill_ka]

I tried your project on my HP3478A and it doesn't do anything when I press SRQ.

I just checked the source... The SRQ key is disabled by default, so you either need to program the provided eep file or enable it with OX1w serial command.