[volt-nuts] New HP3458A

[Bill Gold]

Randy:

    The blinking square when you push auto zero is perfectly normal.  It is
now waiting for you to give it an answer. By pushing either the "^" up arrow
or "v" or down arrow on the keypad set located below the display on the
lower row left side, you will get the menu options for auto zero of "ON",
"OFF" or "ONCE".  You make your selection and then press the "ENTER" key on
the "MENU/USER" keypad set, lower row right hand side.  The 3458A has a
large set of measurement options that you can select.  Read the manual.
These are accessed either through the IEEE-488 or the front panel keypads.
You can get a refurbished "display" PCB from Keysight for $272 exchange
which should cure all of your display problems.  P/N 03458-66517.  It is
easy to replace.  Read the manual.  Check the Keysight website for details.
SCAL is difficult to check without special equipment such as a AC/DC thermal
converter.  The NVRAM can be an issue depending upon the date codes on the
NVRAM devices.  Replacing them is time consuming but can be done.  But you
lose your calibration unless you can read the old ones and then program the
new ones.  Be sure to put in sockets when you replace the NVRAM.  Why HP
didn't do this is beyond me.  Precision machined sockets hold the NVRAMS so
tightly that it is almost impossible to get them out.  Someone suggested
that the weight of the NVRAM devices might allow them to come out of the
sockets during shipment but I just don't see how with the proper sockets.
It sounds like DC and Ohms are working OK.  Passing self test is a good
sign.

Bill

----- Original Message ----- 
From: "Randy Evans" <randyevans2688 at gmail.com>
To: <volt-nuts at febo.com>
Sent: Thursday, August 14, 2014 8:22 PM
Subject: [volt-nuts] New HP3458A


> I picked up a used HP3458A today, which I needed for some precision DC
> measurements i need to make. It passes all the self tests and the Auto Cal
> but is there any thing else I can check ( I have a 14 day RR).  It reads a
> 10V standard I made within a few tens of ppm, but it's not a 732A but that
> is at least comforting.  It also reads an ESI 10Kohm standard resistor
dead
> on.
>
> The only problem is that the display has some faint pixels in some
> locations, with three in the second row for every digit location dead.
>  Likely a pixel driver I would think.
>
>  I am not too familiar with it yet but I noticed when I push the auto zero
> button, the display has a blinking square until I hit a measurement mode
> button; e.g., DCV, ACV, OHM, etc.  Is this normal?
>
> Regards,
>
> Randy Evans
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