[volt-nuts] New HP3458A

[Todd Micallef]

I meant to say Guard and Lo.

On Sat, Aug 16, 2014 at 5:47 PM, Todd Micallef <tmicallef at gmail.com> wrote:

>
> ...The CLIP shows nothing else in between ground and guard...
>
> Todd
>
>
> On Fri, Aug 15, 2014 at 11:06 AM, Jason Watson <watson.jason at gmail.com>
> wrote:
>
>> I've also seen excessive Guard to Low leakage when varistor RV501 has gone
>> bad (it's located on the front/rear switch pcb and it's possible to
>> replace
>> it while leaving the circuit board in place if you are careful).
>>  HP/Agilent/Keysight Part number is 0837-0196, cross referenced to a
>> Harris
>> Corp. V430MA3A.
>>
>>
>> On Fri, Aug 15, 2014 at 10:46 AM, Stephen Grady <grady.steve at gmail.com>
>> wrote:
>>
>> > Randy,
>> >
>> > I have come across a few 3458A's that had leakage between Guard and Low
>> > when
>> > te guard is in external guard position. This was due to a leaky external
>> > guard switch and/or leaky front rear switch. This can be quickly
>> determined
>> > by measuring resistance between guard and low with guard external. This
>> > normally in not an issue except when you are using 3458A to measure
>> voltage
>> > with low above earth potential say in a bridge the guard low leakage
>> will
>> > be
>> > loading other arm of the bridge.
>> >
>> > Kind Regards,
>> >
>> > Steve Grady
>> > Sydney, Australia
>> >
>> > -----Original Message-----
>> > From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
>> > Behalf Of Randy Evans
>> > Sent: Friday, 15 August 2014 1:22 PM
>> > To: volt-nuts at febo.com
>> > 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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