[volt-nuts] HP 3458A repair.

Wed Sep 18 16:50:41 EDT 2013

I talked with Gary... it sounded more like a sales pitch like they replace
relays before they failed. The date code on the cal ram is 6 years past
replacement.  The only problem seems to be the amplifier/attenuator
 flatness. He said this could be caused by caps aging and changing value.
They tried calibrating the AC but it did not come withing spec so they did
not update the as left data... I think if they are going to send the as
left data it should be real as left or blank. This meter looks like a good
meter for what I will use it for so we will not use the AC above 2MHz as if
we ever did.

On Wed, Sep 18, 2013 at 9:17 AM, J. L. Trantham <jltran at att.net> wrote:

> I agree with your assessment of an 'old' meter being more desirable.
>
> I would recommend a conversation with Gary Bierman if you have not already
> done that.
>
> Joe
>
> -----Original Message-----
> From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
> Behalf Of John Phillips
> Sent: Wednesday, September 18, 2013 10:45 AM
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] HP 3458A repair.
>
> The meter will be here in a few days. I did buy the ram. As far as the
> meter
> age goes, unless it is a very old hardware revision, I would rather have an
> old meter because it is more stable. That is until it brakes.
>
> I do have before and after readings and the 4 readings are the only ones
> that failed. The after readings are better than the before readings.
> Because the 8 and 10 MHz failed we did not get a certificate but we do have
> a good limited calibration up to 2 MHz. Just no official cal.
>
> The cal we wanted was $1600. We will still have to pay that after the
> repair.
> From what I can tell they did not run SCAL or the before/after readings
> would not have matched. Like they really did not run after readings or
> there
> would have been some mismatch.
>
>
>
>
>
> On Tue, Sep 17, 2013 at 6:50 PM, J. L. Trantham <jltran at att.net> wrote:
>
> > John,
> >
> > Can you give us more information?  Serial number, Rev. number, CALNUM?
> > How much to invest will be determined by age and other condition.
> >
> > It doesn't sound like a simple CALRAM issue but changing the CALRAM is
> > relatively easy.  I removed all three DALLAS chips in mine and
> > installed sockets.  The CALRAM can be read with a chip programmer and
> > the data written to a new DALLAS chip.
> >
> > I would also call Gary Bierman at the Loveland Cal Lab and have a long
> > talk with him.  He has a lot of insight into these meters and
> > generally prefers to do a component level repair rather than an
> > assembly level repair.  The charge sounds like their standard repair
> > charge, no matter what the problem is, and includes a 'fresh
> > calibration' along with a warranty, a year I think, but Gary will be able
> to answer that question.
> >
> > Also, once you get the meter calibrated by Agilent (and thus prove it
> > is functioning normally) it will be eligible for their 'repair agreement'
> > which
> > is $178.68 per year.  I would consider buying a 5 year agreement after
> > the repair.
> >
> > Good luck.
> >
> > Joe
> >
> > -----Original Message-----
> > From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com]
> > On Behalf Of John Phillips
> > Sent: Tuesday, September 17, 2013 3:36 PM
> > To: Discussion of precise voltage measurement
> > Subject: [volt-nuts] HP 3458A repair.
> >
> > Hi,
> > I have a 3458A that we sent to Agilent for calibration which it failed.
> > Before we sent it we calibrated it and it looked good to us. The
> > infor. we revived led us to believe that the cal memory may have caused
> the failure.
> >  We ask that it be sent buck to us and paid half the cal charges
> > (about
> > $800) insted of the $2660.64 they wanted to repair it. We were just
> > going to repalce the ram in try again.
> > When we got the meter back it came with befor and afer data Like
> > before 10 volts read 9.9999957 and after it read 10.00009 so they did
> > something or the meter drifted that much.
> > The problem is  0.1 volt and 1.0 volts failed at 8 and 10 MHz but
> > passed at
> > 4 MHz.
> > 4MHZ 0.1 volt reads 0.097251 Lower Limit is 0.095930 PASSED 8MHZ 0.1
> > volt reads 0.085712 Lower Limit is 0.0959
> > 2
> > 0
> > FAILED
> > 10MHZ 0.1 volt reads 0.75569 Lower Limit is 0.084900 FAILED
> >
> > 4MHZ 1 volt reads 0.97272 Lower Limit is 0.95930 PASSED 8MHZ 1 volt
> > reads
> > 0.86389 Lower Limit is 0.95920 FAILED 10MHZ 1 volt reads 0.73514 Lower
> > Limit is 0.84900 FAILED
> >
> > The AC after readings are the same. I do not see how AC after could be
> > that identical even if they did not try to calibrate it. Did they just
> > copy the before data and call it after data?
> >
> > My best guess is that if the 4 MHz is in and the higher frequencies
> > are not the meter requires some kind of mechanical adjustment to get the
> frequency
> > response   withing spec or the AC board needs to be repaid.
> >
> > Are they charging a standard repair charge to do a calibration? I do
> > not see changing the memory to fix this.
> >
> > Where would you go from here if this was your meter?
> >
> >
> > --
> > John Phillips
> > _______________________________________________
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>
>
>
> --
> John Phillips
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-- 
John Phillips