Digital scale nightmare.

[Old Bob]

I had a GemPro 250 scale go schizo. After cal it would run OK for about 30min & then readings would start fluctuating up & down. Tried re-cal - no help; shut-down, re-power, re-cal -no help. Tried waiting for about an hour with the scale off. That didn't help any either so I waited 24 hours & that seemed to work but then it would go schizo again after 30min. I used this scale problem free for about 10 years so I figured it was on it's last legs but wanted to try a few more things before giving it the Heave-Ho.

I wound the power cord through a ferrite core to to see if that eliminated any stray RF or fluctuating input-power problems. I didn't see any change. Next, I powered the scale with an external DC power supply that I have. The DC output of that PS is very stable. I don't remember what the AC ripple voltage was but it's pretty quiet. That seemed to work OK. I did one reloading session (almost an all-nighter) without seeing any schizoid problems. I thought the problem was fixed but then the scale went bonkers again the next time I used it with the external DC PS. Oh well!

I have a new digital scale... a Tree Jewelry scale (+/- .02gn sensitivity) that has been rock steady since I got it. It's Chinese but seems to be well made to me.

I never use the plastic specimen/powder pans that come with scales these days. The pans I use are the metal ones from my original RCBS balance scales.