[volt-nuts] A history of the HP 3456A

[Marvin E. Gozum]

I'm collecting a history of this DVM.

Does anyone have any other resources, know of specifics, can check 
the accuracy of what I've already listed, and have personal anecdotes 
of their experience with this DVM?

Items marked ? are considered uncertain and a question for the group.


------- begin history outline -----------

The HP 3456a was introduced into the product line in a feature 
article in HP Journal April, 1981.  3 of its engineers co-wrote the 
article.  Charles A. Clark developed the true-rms converter. Jim 
Ressmeyer did thin-film hybrids and analog design for voltmeters, 
including the 3455A DVM; he was responsible for the ohms, input 
filter, and front-end switching sections.  Larry Jones worked on the 
dc section.

The 3456a entered the HP catalog in 1981 and listed for $3500.  It 
was later incorporated as an optional DVM for the HP 3054c data 
acquisition system, until it was discontinued.

Catalog Highlights:

1986
3456a listed for $4000
3457a first introduced into the catalog and listed for $2800

1989
3458a was introduced for $6000

1993
3456a Last listed for $6400


During its production run several versions were made, but a large 
number of internal changes were in the 2015A serial number series, 
and all changes are documented in the HP 3456a Service and 
Calibration manual.  There were no changes to performance 
specifications from the original design of 1981.  The service manual 
at Agilent's website refers to the 2201A series and prior 
models.  Circuit operations characteristics as described by Clark, 
Ressmeyer and Jones in their paper are described in the service 
manual, with far more detail, particularly in the 'theory of operation'.


2015A Series
NB: notifiable features
Cooling fan and air filter in rear panel
ROM model changes

2201A Series
NB: noticeable features
Fan and filter now absent
power regulator LM323K exposed on rear panel

2512A Series
NB: noticeable features
Introduction of soft mechanical switches replace the original hard 
tactile-feedback switches on front panel ?

2943A Series
NB: noticeable features
Last series prior to being discontinued ?



Notations by other individuals regarding 3456a, about device failures 
other than from physical abuse or electrical accident:

ROM failures


Stepan Novotill posted a detailed repair note on the failed PROMs in 
the 3456a.  2015A series is primarily affected ??  A series appeared 
on the yahoogroup,
hp_agilent_equipment, in 2007, but no further threads have appeared 
before or after it.

Q: Have other serial numbers been affected, anyone with personal experience?


Other Failures

A common failure [ but rare reports] in the 3456a are capacitor 
failures in the power supply.  It affects all models, older ones and 
unused ones more common that those in actual service?  I've person 
experience with failed power supplies in 2 3456a each in the 2015A 
and 2201A series.





References:
L.T. Jones, J Ressmeyer, C.A. Clark. "Precision DVM Has Wide Dynamic 
Range and High Systems Speed," HP Journal. Vol. 32, no. 4, pp. 23-32. 
April 1981.






Sincerely,



Marv Gozum
Philadelphia, PA