[volt-nuts] HP 3457A Arrived

[Joseph Gray]

It did work until I put everything back together. Now it is back with the
same HARDWARE ERROR. I'm going to have to do a full tear down and take a
very hard look at everything.

The seller told me that this was his personal bench meter for the last four
years and that it was working 100% before he shipped it. I have no reason
to doubt that. I suspect that something got jarred in shipping and is
either loose or shorted. I hope it isn't a cracked trace.

I read the CALNUM and it was 34. There are remnants of anti-tamper labels
on some case screws from these guys: http://www.ssclabdivision.com. So, it
has perhaps been calibrated/adjusted at least once since manufacture.

I downloaded the Scope of Accreditation document for the above lab. Am I
interpreting things incorrectly, or do the uncertainties for DC voltage
source (in particular) look large?

One very odd thing that I noticed when it was open was the remnants of a
wire that had been tack soldered to what looks like a voltage regulator.
See the picture here:
https://dl.dropboxusercontent.com/u/19599147/HP%203457A%20Oddity.jpg

Joe Gray
W5JG




On Thu, Aug 22, 2013 at 1:31 PM, Joseph Gray <jgray at zianet.com> wrote:

> I got the OK to open the 3457A. I didn't see anything that was obviously
> loose or broken. I reseated all connectors and also the socketed ROM. It
> now powers up and passes self test (at least twice so far). I did all this
> over lunch, so tonight I will be taking an even closer look at things.
>
> While I had it open, I looked it over a bit. All the chips are dated late
> 1991 or early 1992. The old optocoupler has been replaced by two chips that
> span the slot in the board.
>
> The battery looks like it is probably original. The solder connections
> don't look re-done. The battery is a Panasonic BR-2/3AE2SP. The tab on one
> end has one point, the other end has two. Mouser sells these for $5.24.
>
> Joe Gray
> W5JG
>
>
>
> On Wed, Aug 21, 2013 at 5:34 PM, Joseph Gray <jgray at zianet.com> wrote:
>
>> Boy, I have the worst of luck. I think Murphy follows me around. I won't
>> bore you with the details about my recently dropped by Fedex service
>> monitor and major repair cost.
>>
>> The 3457A arrived. Other than missing feet, it looked in decent
>> condition. I powered it up and that is when things went wrong.
>>
>> The first several times, on power up, I got the Address display and the
>> beep, but instead of going to DCV, it displayed PASSED, with an occasional
>> FAILED. It would do this seemingly forever.
>>
>> Once, it powered up normally, then froze. Another time, it powered up
>> normally and I managed to read the error code (1 - Hardware error) and the
>> auxilliarly error (1 - Isolation error durring normal operation).
>>
>> Later, it would power up and immediately display FAILED. At this time, I
>> happened to lift the front of the cabinet and saw that FAILED and PASSED
>> would randomly alternate on the display. Something is definitely loose.
>>
>> I would have already opened the DMM up, except the seller applied
>> anti-tamper labels to the case screws (I have a 30 day warranty). I have
>> sent all of this information to the seller. Hopefully, he will authorize me
>> to open the case and see what is what. Otherwise, I have no choice but to
>> return the DMM.
>>
>> Joe Gray
>> W5JG
>>
>>
>