Electronics > Metrology

Fluke 5440A repair

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MegaVolt:
While I'm looking for a replacement resistor I tested the rest.

Some show stable hysteresis to one side. For example, the resistor in the picture adds 5ppm after each heating.

As a result after 20 turns on of the device we will have 100 ppm. I think this is a lot.

Is it worth to change such resistors?

MegaVolt:
I returned :)

1. Corrected the scheme. C5 fixed to C16.
2. I drew a board with tracks. (this file is for Photoshop layered. Let me know if you need it >50MB)

leighcorrigall:

--- Quote from: MegaVolt on September 20, 2021, 08:27:40 am ---
...


--- Quote ---For the black dot, this may be from inital selection of the parts. One finds dot's on slected chips quite a lot.

--- End quote ---
It's not like the usual dots. It looks more like it was painted over.

...


--- End quote ---

The black dot does appear on another reference board that I have. It may help distinguish one SZA263 from the other when selected resistors are being installed.

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