[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.





More information about the Time-nuts_lists.febo.com mailing list