[volt-nuts] New HP3458A

[Todd Micallef]

Randy,

I have had two 3458a that had bad front / rear switches. It was easy to determine during the calibration of the Cal 0 that failed. A copper short across both of the inputs, as per the calibration procedure, showed more than .5 ohm in 2-wire mode on the lowest range. The resistance was not stable and seemed to settle slowly. The switches were available and not hard to replace but probably not something I would attempt with a ROR unit. 

The pixels can have some burn-in, but I don't know if Agilent/Keysight would fail a cal for dead pixels. There was no indication that they looked at this during the calibration. They use the GPIB port and probably would fail it if the display was not readable during self-test. A call to Keysight would probably help. I think the displays are in the $700+ range. That reminds me, you should check the GPIB port. Mine was not functioning when Agilent received the meter, but then it started working when they bench tested it. It almost cost me $2700 .

The ACAL ALL passing all tests would be a good sign, but I am not sure if it indicates that the SCAL calibrations will pass. Someone else can probably help with that potential issue.

The age of the NVRAM is important. Can you determine when they were replaced ?

Todd
Sent from my iPad

> On Aug 14, 2014, at 23:22, Randy Evans <randyevans2688 at gmail.com> wrote:
> 
> 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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