Empathy List Archives

volt-nuts@lists.febo.com

Discussion of precise voltage measurement

View all threads

I got the cal. data saved of a 3458A

Frank Stellmach

Fri, Aug 2, 2019 7:47 AM

Hello Miguel,

I had a closer look at the pictures on
https://xdevs.com/fix/hp3458a/#a5pcba.

Therefore, on this new A5 PCB, it's not possible any more to program any
SRAM outside the instrument.

For the CALRAM, the working / setup RAM and the optional data RAM, they
instead use 2x 128kB SRAMs in SMD, (Cypress CY62128BLL) which are
buffered by 2x M40Z111 supervisory / battery backup circuits, where you
would also replace these batteries.

The batteries are available from Farnell or digikey, but maybe not in
your country, because these are not allowed to be sent by airplane.

You could buy either the M4Z28, or better the M4Z32 batteries.

As the uploading program from Poul-Henning is not available, you only
have to live with the (small) danger of corrupting the data, and needing
a new calibration, but latter might be required anyhow.

I would recommend that you first familiarize yourself with the 3458A,
and enjoy this wonderful instrument.
Later on you could take on with some volt-nuttery, i.e. build your own
LTZ1000 and a 10k resistance reference, let it have calibrated @ other
volt-nuts, and then you would be able to adjust the basic 10V and 10k
references of your 3458A on your own, that's sufficient for private use,
I think.

Frank

Hello Miguel, I had a closer look at the pictures on https://xdevs.com/fix/hp3458a/#a5pcba. Therefore, on this new A5 PCB, it's not possible any more to program any SRAM outside the instrument. For the CALRAM, the working / setup RAM and the optional data RAM, they instead use 2x 128kB SRAMs in SMD, (Cypress CY62128BLL) which are buffered by 2x M40Z111 supervisory / battery backup circuits, where you would also replace these batteries. The batteries are available from Farnell or digikey, but maybe not in your country, because these are not allowed to be sent by airplane. You could buy either the M4Z28, or better the M4Z32 batteries. As the uploading program from Poul-Henning is not available, you only have to live with the (small) danger of corrupting the data, and needing a new calibration, but latter might be required anyhow. I would recommend that you first familiarize yourself with the 3458A, and enjoy this wonderful instrument. Later on you could take on with some volt-nuttery, i.e. build your own LTZ1000 and a 10k resistance reference, let it have calibrated @ other volt-nuts, and then you would be able to adjust the basic 10V and 10k references of your 3458A on your own, that's sufficient for private use, I think. Frank

Miguel Yepes

Fri, Aug 2, 2019 9:42 PM

Thank you.
I ordered from Ebay send by post office no problem 2 M4Z32 batteries zeropower so I dont need the one with the timekeeper clock.
I saw on youtube on mjlorton channel that youy can replace the batteries with the unit on without losing the data. I will send to calibration latter.
I cant change the ove temperature as my place the temperature fluctuates a lot the weather in Monterrey, Mexico gets to 0ºC all the way to 44º on summet time.

Thank you. I ordered from Ebay send by post office no problem 2 M4Z32 batteries zeropower so I dont need the one with the timekeeper clock. I saw on youtube on mjlorton channel that youy can replace the batteries with the unit on without losing the data. I will send to calibration latter. I cant change the ove temperature as my place the temperature fluctuates a lot the weather in Monterrey, Mexico gets to 0ºC all the way to 44º on summet time.