Discussion Category: Balances
MT5 giving Err Load
We have just obtained a surplus MT5, which was in a working industrial lab for many years. Its basic function seems good; the menu displays are what I expect, the draft shield moves properly, etc. At present it disagrees by about 1 mg with a recently-calibrated analytical balance on the mass of a 650 mg weigh boat.
However, when I initiate a self-calibration, it fails. I get a 'cal 0' message, then 'cal', and at this latter stage the 'delta' radial indicator suggests that the load is near the upper limit for the balance. This 'cal' indication disappears, and then after a few seconds I get an 'Err Load' error indicator.
I have removed and cleaned the balance pan twice. It's not pristine, but it seems pretty doggone good. As far as I can tell it doesn't have anything stuck to its post. I can weigh a little bit of tissue and get a reading of 126 micrograms with the expected behavior, with no indications that the movement of the balance pan is restricted.
What other than a dirty pan can cause the Err Load message? Is it likely that the reference weights are dirty or damaged? Can anyone suggest diagnostic checks that would be useful?
Thank you!
-George.