Products > Test Equipment

[SOLVED]HP/AGILENT/KEYSIGHT 34401A 2W Ohm Problem

<< < (8/11) > >>

Dr. Frank:
Well, please make a cross check over time, with a solid short in 2W mode.
Should read <0.2 Ohm or less, and be stable over time.
That's what I expect strongly, as your instrument should be ok again, after repair.

The resistor has got 5ppm/K, so no chance that the drift of 0.2Ohm in your picture comes from heating up.. that would require 4000°C.

You obviously simply wrapped the leads of the resistor around the posts- that makes no good contact at all.
This is the most probable root cause.
Please solder that resistor to the posts.

Perhaps the jacks themselves do not make contact very well.
That could be the reason, why the 4W measurement gives stable results... looks strange,, anyhow.

4W measurements give always smaller values than 2W measurements.. So test your instrument with a short first..

As you have a low Ohm resistor, you should use 4 jacks for the resistor box anyhow, i.e. 4 pole Kelvin connection.
All the contact resistances kill the accuracy of your resistor.

Frank

coldframe:

--- Quote from: Dr. Frank on February 18, 2014, 04:51:25 pm ---Well, please make a cross check over time, with a solid short in 2W mode.
Should read <0.2 Ohm or less, and be stable over time.
That's what I expect strongly, as your instrument should be ok again, after repair.

The resistor has got 5ppm/K, so no chance that the drift of 0.2Ohm in your picture comes from heating up.. that would require 4000°C.

You obviously simply wrapped the leads of the resistor around the posts- that makes no good contact at all.
This is the most probable root cause.
Please solder that resistor to the posts.

Perhaps the jacks themselves do not make contact very well.
That could be the reason, why the 4W measurement gives stable results... looks strange,, anyhow.

4W measurements give always smaller values than 2W measurements.. So test your instrument with a short first..

As you have a low Ohm resistor, you should use 4 jacks for the resistor box anyhow, i.e. 4 pole Kelvin connection.
All the contact resistances kill the accuracy of your resistor.

Frank

--- End quote ---

All right, I will try immediately!
Thank you for the tip.

coldframe

Dr. Frank:
Ups.. don't you own a simple, short lab cable with decent plugs, to short Hi and low in 2W mode???

Frank

coldframe:

--- Quote from: Dr. Frank on February 18, 2014, 05:42:26 pm ---Ups.. don't you own a simple, short lab cable with decent plugs, to short Hi and low in 2W mode???

Frank

--- End quote ---

Dr. Frank
My apologies. I don't understand what you mean.

Dr. Frank:

--- Quote from: coldframe on February 18, 2014, 06:00:51 pm ---
--- Quote from: Dr. Frank on February 18, 2014, 05:42:26 pm ---Ups.. don't you own a simple, short lab cable with decent plugs, to short Hi and low in 2W mode???

Frank

--- End quote ---

Dr. Frank
My apologies. I don't understand what you mean.

--- End quote ---

I asked you to make a test in 2W Ohm, shorting High and Low with a simple laboratory cable with good plugs.

What you are showing, looks not so good.

If you simply do the test, you can see, if the 2W mode is working correctly and if the zero is properly calobrated, after your repair.

Frank

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod