Re: Electronic vs Balance Beam scales
For those of you with problems holding Zero, An uninturuptable power supply (UPS for your computer, purchased at any office store) should be in your future.
While not related to scales, I deal with motion control using electronic controlers. In the field when we run into unexplainable control issues, we commonly find that some repeatability problemes are related in some way to dirty power. Could be poor grounding, fluctuating voltage, weird voltages etc.
A UPS is a good way to even out some power problems...its esentially a battery that isolates the grid from your equipment. flattens and conditions the power to be more consistant.
Another thing to look at is induced voltages related to proximity to higher voltages. (is your scale near the high voltage lines running to your panel?) I once had a customer replace all the servo drives on a machine because it wouldnt work) later found out it was sitting directly over the 27000v lines running into the factory. Moved the machine and POOF! no more problems.
On site conditions can make a huge difference to reliability...