[time-nuts] new request for HP 3458A info
Dick Moore
richiem at hughes.net
Sat Aug 1 19:25:39 UTC 2009
Thanks Greg Burnett and Frank Stellmach -- good suggestions. I should
have provided a bit more info. On power up, the display usually shows:
-OVLD DCV
Then when I run self-test, I most often get the 209 error.
The CAL? values are good, which is reassuring. I'm thinking it's in
the DC front-end somewhere as Greg suggested.
Frank, this instrument came to me completely untested and not powered
up by the seller -- the power button and actuating shaft are missing,
which makes me think it was in a lab or ATE setup where an accidental
power off would cause big problems. It is in generally very good
physical condition and is very clean.
I don't have schematics for this box. I do have a right-of-return for
refund, which I will most likely exercise.
Best,
Dick Moore
On Aug 1, 2009, at 11:28 AM, time-nuts-request at febo.com wrote:
>
> ".. internal overload: 72" might be caused by a failure on
> calibration,
> as '72' might refer to the 'dcv 10V gain' (see calibration manual p.
> 5-6).
>
> Either an ACAL failed, caused by interrupting this process, or an
> attempt to calibrate the internal 7V reference has gone wrong, also
> because of interruption, or because of unstable / inappropiate
> external
> voltage reference.
>
> Please read out cal constant 72 by "CAL? 72", on my instrument it's
> 1.00435...
> If you scroll the text to the rightmost, an additional string states
> if
> the calibration constant is valid.
>
>
> Then read out cal constant 2 by 'CAL? 2', that's the internal 7V
> reference. Should be betw0en 7,0V and 7,5 V, acc. to LTZ1000
> datasheet,
> but typ. around 7,2V. It's 7,2165..V on my 3458A. Again, scroll the
> text
> righmost, if the constant is valid.
>
> If 7V ref constant is corrupted or out of range, a basic calibration
> might help.
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