[volt-nuts] 3458A - To Modify or Not To Modify?
J. L. Trantham
jltran at att.net
Tue Nov 8 01:14:08 UTC 2011
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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