[volt-nuts] 3458A - To Modify or Not To Modify?

J. L. Trantham jltran at att.net
Tue Nov 8 01:37:19 UTC 2011


Steve,

Got em.  U132 image is TOTALLY different from mine and much more of what I
expected.

I re-read U132 and it is somewhat different every time I read it.  Sounds
like it is 'toast'.

Joe

-----Original Message-----
From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
Behalf Of Steve
Sent: Monday, November 07, 2011 7:20 PM
To: Discussion of precise voltage measurement
Subject: Re: [volt-nuts] 3458A - To Modify or Not To Modify?

Joe,

On the way!

Steve



On Nov 7, 2011, at 7:14 PM, "J. L. Trantham" <jltran at att.net> wrote:

> Steve,
> 
> I would love to see them.
> 
> Joe
> 
> -----Original Message-----
> From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
> Behalf Of Steve
> Sent: Monday, November 07, 2011 6:07 PM
> To: Discussion of precise voltage measurement
> Subject: Re: [volt-nuts] 3458A - To Modify or Not To Modify?
> 
> Joe,
> 
> I have the images from the chips in my 3458A. They had '94 dates so a few
> months ago I unsoldered them, read them, installed machined-pin sockets
and
> burned new chips, and the meter came up with no problems. I hope to send
it
> to Loveland soon. I'm on the road for the week but have asked a fellow ham
> to send me a copy of the files as we did the reading and burning at his
> place.
> 
> Steve
> 
> Sent from my iPad
> 
> On Nov 7, 2011, at 5:23 PM, "J. L. Trantham" <jltran at att.net> wrote:
> 
>> Bill,
>> 
>> I don't know if I have damaged my 'cal' DS1220Y or not.  The two
DS1230Y's
>> had files that looked like what I was expecting when I read them.  On the
>> DS1220Y, the original read on my BP-1600 gave an over current warning and
>> shut down.  The chip was a bit warm from the unsoldering and, perhaps,
> that
>> was it.  I then moved it from my BP-1600 to an Advin MVP and it read
>> promptly.  I then re-read it on the BP-1600 and it read promptly.  So,
> don't
>> know.  Would be nice to find an image to compare with just to get an idea
>> about what it should look like.
>> 
>> That chip had a date code of 9713 and the two DS1230Y's were 9703.
>> 
>> In any event, new sockets and chips are on the way.  If I have lost my
>> calibration constants, I would anticipate that the meter is still
> 'calable'
>> which is what I am hoping for.  Then, once it gets back from Agilent, I
> will
>> be able to harvest the data from the new chips, archive it, and be in
>> business the next time the chips fail.  Then, again, my current chip may
>> still be OK.
>> 
>> Joe
>> 
>> -----Original Message-----
>> From: volt-nuts-bounces at febo.com [mailto:volt-nuts-bounces at febo.com] On
>> Behalf Of Bill Gold
>> Sent: Monday, November 07, 2011 11:31 AM
>> To: volt-nuts at febo.com
>> Subject: Re: [volt-nuts] 3458A - To Modify or Not To Modify?
>> 
>> 
>> Joe:
>> 
>>   When I removed my original NVRAM, put in the sockets and then installed
>> the original NVRAM I got a few error messages when I turned the meter
back
>> on.  I don't remember exactly what the complaint was but it involved a
few
>> calibration constants missing and the calibration password missing.  My
>> initial guess was that the batteries were gone and desoldering the NVRAM
>> just finished the process.  The date codes on the NVRAM was 1989 so I was
>> just running on borrowed time anyhow.
>> 
>>   I don't have a ROM programmer anyhow so I just installed the new NVRAM
>> and did a full calibration to my local standards.  I really don't care
> about
>> traceability to NIST anyhow.  What I have here is close enough for what I
>> do.
>> 
>>   I have tried to find out what material is used for the pins of the
> NVRAM
>> is but no such luck from the Maxim/Dallas package datasheets.  My guess
>> would be the usual tin plate.  Yes, gold against tin isn't the best idea,
>> but it is better than tin against tin.  You are simply not going to find
>> these NVRAM with gold plated pins so you have no choice.  I forget
whether
>> the gold migrates into the tin or the tin migrates into the gold.  When
we
>> specified the plating of the "fingers" of our PC Boards, we used nickel
> over
>> the copper and then 60u of gold over the nickel.  This gave the best
> results
>> for constant insertion and removal of the PC Boards from the mother board
>> sockets, which were gold plated.  We produced expensive ATE for Discrete
>> Semiconductors, in the range of $100k to $200k each, so we wanted
>> absolutely, positively good contact all the time and no failures due to
>> repeated removal and insertion.
>> 
>>   IMHO you are on the right track.  Let's see what happens when you
>> finally get the Loveland calibration.
>> 
>> Bill
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