Electronics > Repair
Agilent 34401A Bubble on PCB ... can it be saved ? (SOLVED)
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coppercone2:
its not a bad analogy how it hides under ceramic and prevents a system from functioning and its hard to get out
Kleinstein:
I would still wait a little before sending the meter out to calibration. One point is waiting for settling after the disturbance from soldering. There is likely PCB stress and a disturbed humidity and this can cause some drift for the next few days / weeks.  Just after a repair there is also a slighly increased chance to get another defect, a little like with a brand new meter.

Another point is first doing a few more checks to see if the meter really works. There may be other, less visible defects / problems.
A relatively easy part to check is the input bias current, e.g. in the 10 V DC range. This can be checked from the rate a low leakage capacitor of some 10 nF charges or discharges.

Another point can be the drift during warm up. Excessive drift could point to a hidden defect. Here one may need some stable reference, so not so easy a test.
The_Spectrum.A_idiot:
Another question for the experts ,

I spoke with 2 labs today.
1 was recommended by keysight
1 is a local lab.

The recommended keysight lab said that will verify the instrument and all its functions , will give a certificate of calibration. BUT if any of the functions have any deviation will give a limited certification with a deviation factor. I would like to know if this is standard OR I didn't convey my thoughts to the guy at the other end of the line correctly?

In my mind calibration means that I am forcing the instrument to measure a known thing and replace whatever value its measuring with the proper one.

so IF I am measuring a 1M standard that is 1ppm and the instrument is 40ppm and the instrument measures 0.98M then by calibrating the instrument means I am making modifications via the software to force the meter to get the measurement from 0.98M to 1M and adjust whatever values are wrong in its memory to account for age and wear and tear , then I am testing the linearity of the instrument. If all goes well means the correction was successful.

As far as I understand what they provide is just a proof testing that indeed the instrument is measuring what is real +/- the allowed deviation or error from the datasheet. And just say that this instrument is measuring the values as close to reality. Nothing else.

Is this what calibration means in the real world ?

The local lab asked me to email them the datasheet and instrument brand and model and they will get back to me. (most probably won't be able to verify it leat alone calibrate it in the way I have it in my mind)

Let me know if there is a better way to ask what I have in mind.

Thank you in advance for your time

The Spectrum.

coromonadalix:
if the instrument normally pass self tests, you should be able to get a full certification

BUT   yes it could pass self tests (i dont know the precision of the internal tests done)    and maybe fail  if it is at the "out of tolerance" limit or goes beyond that ...

and yes you could still get a limited certification,  AND accept or refuses it,  but fee's can or could be charged to you either way  ...  (Here in my country they work like that, if it pass or fail)


the best would be find some people who can check it  BEFORE doing certifications,  maybe in the TEA thread some people could help ?

yes  some wrote, the best would be  to run the meter for a few days and try to see  if it deviates,  even a good cleaning could still leave traces ...  re re and re check ...   this meter has gone thru a lot  ... i mean a lot ...  you have to be sure

the  meter is a good piece of precision,  if it goes well, it may or will be precise for many years,  i had 3x  of them (1 xformer blown, 1 dim vfd, and one fully recapped),   the later received a full certification (but frankly it was still in the specs after a decade) ..

if the meter do and does precision measurements,  you need to get it certified,  or if its a "toy" or non precise stuff and nothing depend or need the be certified BY YOUR meter,  you can use it like this, but you'll never know  unless doing some good checks  with precision parts in the 0.5 %  0.05%  ...    i have Fluke 0.013% precision resistors  ...

if a local lab ask you specs  mmmmmmmm  i would not be sure of their capacity ... 
normally you need  Fluke calibrators or else  in the 7 or 8 digits of precision
The_Spectrum.A_idiot:

--- Quote from: coromonadalix on September 25, 2024, 04:10:13 pm ---if the instrument normally pass self tests, you should be able to get a full certification

BUT   yes it could pass self tests (i dont know the precision of the internal tests done)    and maybe fail  if it is at the "out of tolerance" limit or goes beyond that ...

and yes you could still get a limited certification,  AND accept or refuses it,  but fee's can or could be charged to you either way  ...  (Here in my country they work like that, if it pass or fail)


the best would be find some people who can check it  BEFORE doing certifications,  maybe in the TEA thread some people could help ?

yes  some wrote, the best would be  to run the meter for a few days and try to see  if it deviates,  even a good cleaning could still leave traces ...  re re and re check ...   this meter has gone thru a lot  ... i mean a lot ...  you have to be sure


if a local lab ask you specs  mmmmmmmm  i would not be sure of their capacity ... 
normally you need  Fluke calibrators or else  in the 7 or 8 digits of precision

--- End quote ---

I will run it the next month , But I need to get some precision resistors , I have a GBID ( that interface ) to capture the readings ( it even has serial ).
And maybe use 4W and 2W measurements to test said resistors.

The most difficult would be for voltage and current ( as I have no idea what can be that stable while measuring it , a battery is out of a question )

Because they said their stuff is still out on calibration aboard.

But my question was if this is normal to just verify the instrument and not adjust it via its calibration menu etc etc ...

Anyway slowly I will get it done somehow. I will email keysight too what is their normal procedure in case of non conformities ...


--- Quote ---if a local lab ask you specs  mmmmmmmm  i would not be sure of their capacity ... 
normally you need  Fluke calibrators or else  in the 7 or 8 digits of precision

--- End quote ---

My thoughts exactly ! That's why I will send it abroad.
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