In a moment of utter madness I've bought another 3458A ... I don't really know why, I guess I'm addicted!
Anyway, it was a faulty unit with a high memory error, which I've already fixed with my previously used FRAM boards for memory and cal data.
It also had a fan that sounded more like a circular saw - now replaced, and the front terminals had been pushed back and broken the plastic screw fixings off of the front panel ... now fixed with a 3d printed part and some epoxy.
But ... the GPIB interface isn't working, nothing detected at all ... I spend bloody ages trying to determine this since my natural assumption was it was a failure with my own-built GPIB interface, but I have now confirmed it works on another 3458A, and another (not of my making) interface also shows the same behaviour.
The connector looks ok and checks out with a continuity tester ... so my assumption is that the GPIB line drivers are faulty ... is that a reasonable place to start?
I haven't started troubleshooting them yet (still waiting for the epoxy to dry!) ... I'm also assuming that it's reasonably easy to see if they are working. I can setup a regular activity and trace the signals through the drivers.
Has anyone else seen these fail?
This unit has a DS75161AN and a SN75ALS160N.
Thanks.
Hi,
Yes, I bought a faulty 3458A a couple years ago and GPIB was faulty, same issue I.e. absolutely nothing.
I replaced both driver IC'S and it was working again.
Ian.
Did they show a HPIB error on startup?
Now fixed.
I was probing the driver IC's with my scope whilst running some repeating comms and everything looked fine .. I then retested and it was fine ... disconnected my scope and it failed again.
The GPIB connector didn't appear to be grounded properly, although the schematic does indeed show a different GND (DCOM2) .. however this did remind me that I'd seen a service note to do with GPIB comms (3458A-13A) so thanks to xdevs I managed to find it and it was indeed the problem.
https://xdevs.com/doc/HP_Agilent_Keysight/3458A/service/3458A-13A.pdfSo all fixed.
Now fixed.
I was probing the driver IC's with my scope whilst running some repeating comms and everything looked fine .. I then retested and it was fine ... disconnected my scope and it failed again.
The GPIB connector didn't appear to be grounded properly, although the schematic does indeed show a different GND (DCOM2) .. however this did remind me that I'd seen a service note to do with GPIB comms (3458A-13A) so thanks to xdevs I managed to find it and it was indeed the problem.
https://xdevs.com/doc/HP_Agilent_Keysight/3458A/service/3458A-13A.pdf
So all fixed.
I've had this same issue on one of my 3458As before. Following this Appnote 13A fixed my issue. Glad to see it has fixed others!
fixed with my previously used FRAM boards for memory and cal data.
@essele
Where did you get the FRAM boards from ?
I'm looking to use FRAM on my '58 , but would love to get a PCB layout for those boards.
Instead of DIY'ing them
/Bingo
Hi Bingo,
They are my own creation and manufactured by JLCPCB. I had a couple left over from my other meter, so it was easy.
The schematics, layout, and gerbers (and a photo) are all attached on this thread:
https://www.eevblog.com/forum/metrology/3458a-upgrade-questions/new/?topicseen#newI was lucky enough to be able to program the CAL FRAM using an SOIC adapter before soldering it to the board. I haven't tried programming it once on the adapter ... obviously it should work, but I've not tested it.
Lee.