Protek DMM calibration procedure?

[IanB]

This seems to be one of those pieces of "secret" information that I can't find by Googling. I bought a Protek 6500 DMM that reads 4.9986 V against a 5.000 V reference. It is within the accuracy spec of ±(0.03%+6 digits), but the lack of exactness still offends me. I would like to tweak the calibration to make it read at least between 4.999 and 5.001 V, but I can't find out how. Does anyone have this information, or know where I might look?

For calibration the meter has a push button on the rear covered by a calibration sticker. I imagine that pressing this button puts the meter in a calibration mode in which the front panel buttons get different functions. But I don't want to experiment. Since it is an inexpensive meter for hobby use I also have no interest in paying for professional calibration. If I could read the calibration instructions I could at least decide whether to have a play or leave well alone...

[alm]

What's the uncertainty in the reference? Are you actually improving accuracy or just making your equipment consistent, which may decrease accuracy?

Sorry, no clue about the calibration procedure. Did you try asking Protek?

[Neilm]

I would be wary of trying to adjust the instrument you have so it reads 5.0V on your 5.0V referance. It might very well make the instrument go out of spec elsewhere.

Neil