[volt-nuts] 3458A resistance calibration

[Electronics and Books]

my 3458 was getting troubles with the calibration of the zero. As volts where no problem and ohm were pretty accurate, my conclusion was that there is basicly nothing wrong. the calibration stopped at the ohm-10. so it must be in the sense lines somewhere. on de dc print there where 2 big resistors (Dale ?) in the sense lines. with a magnifying glass i could spot litle cracks in the solder. after heating with some fresh solder the fault was over.

i have red several times that the standard resistor for ohms should be of a better type. In my 1998 production unit it is a vishay vhp101 40k. that must be one of the better ones that were made by vishay. in an older 1994 unit there was no brand or recognisable type code on it.

Regards

Frans


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