Products > Test Equipment
[SOLVED] 34401a - Cal Error 707
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jlmoon:
Thank you,  I think I am going to order some of the 4897-x series.. I like the idea of streamlined cable exits when stacking them in a complex test arrangement..

Zucca:
Correct guys those are Pomona 1825-0 black 1825-2 red, I made those cables by myself with these wires:

http://www.mouser.com/Search/ProductDetail.aspx?R=6733-2virtualkey56520000virtualkey565-6733-2
http://www.mouser.com/Search/ProductDetail.aspx?R=6733-0virtualkey56520000virtualkey565-6733-0

I spent a lot more than china stuff, but I´m so happy. Moreover you get the length you want... I can only suggest those cool toys.
Zucca:
Quick update, I opened the unit.
The front 4W resistance measure becomes stable with correct values and stop to drift when I press down the entire plastic red front terminal block against the pcb.
I will look at the pcb tracks and do further measures. The solder joints looks good, but after I will try to resolder the terminal inputs.

Worst case the sense lines copper inside the terminal block is cracked.

It's becoming interesting now... I suspect the owner before me played basketball with this unit...
I will post pictures soon.
gaijin:
Would be nice if it was a joint, if it's the block it can be ordered through Agilent.
Zucca:
No!

The front terminal block joints look and measure good:







mmmm...

I also reflow them but the issue was still there...

I then started to follow the sense tracks and, hello 24K resistors... why when I press you the sense line goes from open circuit back to good?
So I reflowed all those six 24K bastards. Actually it looks like three of them had a bad joint (they were invisible to me, I could spot nothing with my naked eyes).

Here after the reflow surgery:


Below now the stable measured series (3x24K) values on the sense lines front and rear (didn´t touch the six 24K on the back):
                     
rear low      72.310 [KOhm], offset 0.43%
rear high     72.319 [KOhm], offset 0.44%
front low     72.070 [KOhm], offset 0.10%                          
front high    72.279 [KOhm], offset 0.39%                            


I got the same problem like coldframe here (thanks again Dr. Frank to point me there)

https://www.eevblog.com/forum/testgear/hpagilentkeysight-34401a-2w-problem/45/

Final check:



passed  :-+

Now I will contact the lab and see if they agree this unit is now back in business.

Bastard 24K Resistors! I allow myself to declare that not only the front/rear switch but also those 24K sense resistors are a weak point of our beloved 34401a.

Finally a big thank to the new big brother on the top which helped to rescue the little one.

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