Electronics > Repair
Repair : HP 3245A precision DC/AC source
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alanambrose:
Any thoughts on what's going on with this algorithm? Why this sequence? Is it exactly fixed or adaptive? There are obviously some checks around the extremities of the ranges - but does anyone have any thoughts on why this sequence in particular? What might the cal data do - some kind of parameterised function applied to the raw reading?
alanambrose:
Ah this is also fairly curious in the cal routine:

"Reading number 45 should be taken on the HP 3458A 100V DC range. Autorange should be used for all other readings."

And reading 45 is shown as ... 0.100220V.

Errr...

They wanted the resolution truncated? There's an interaction between the 3458 cal and the 3245 cal? A tech's idea of a joke?

A.
Kleinstein:
For reading no. 45 it is possibly that they need it as a difference to anouther reading that uses the 100 V range. So to avoid extra errors it might be better to use the 100 V range for this low voltage too. The 3458 still has a good resolution in the 100 V range. 
alanambrose:
Hi,

FYI I just did an analysis of the commands in the firmware compared to those in the docs (see http://anagram.net/nuts/3245a/3245A commands analysis.xlsx ). These ones are apparently undocumented and may be interesting:

BUSYTIME
CALLIMIT
CALREAD
CALWRITE
FREAD
FWRITE
PICKACHAN
RIGGLE
SREAD
SWRITE
WIGGLE

These are there too - similar to the 3458A:

JSR
MADDR
MREAD
MWRITE

A.
TiN:
I thought sequence is rather usual, near full scale pos/neg on specific range, near half scale and near zero. Specific points likely chosen for AC performance cal points, by some internal math derivatives.
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