How do I fix a broken electronic scale?

[NeoPTLD]

I think my scale is broken. It's set-up on a level surface and the bubble level is centered.
It is left on continuously as recommended.
The calibration adjustment was performed with a draft attached at zero and 200.000g and it goes through without errors. The spec calls for repatability of +/- 0.001g, but it's more like +/- 0.2g and the corner load is wildly off, something like +/- TWO grams.

Pic

It doesn't use a strain-gauge load cell commonly found in bathroom scales. It has a magnetic force restoration type sensor with moving parts.

 

[Paperdoc]

If you're not an instrumentation tech you might be better to have this done by a pro. But if you're used to doing some simpler work on such equipment, my suggestion is to look closely for junk or dirt that is jammed into the mechanism and causing it to hang up. Usually the top pan simply lifts off, so do that first and see if there's something under it on the case top, or maybe some junk has slipped down the opening in the top where the pan support shaft emerges. If nothing is obvious there, you will have to decide whether you feel comfortable unplugging the scale and removing the covers to look for foreign materials inside the case that might be brushed out. Either way, reconnect the power and see whether the scale behaves properly. Once those things are done, I personally would not try to change or adjust anything else. Without complete knowledge, manuals, skills and tools, your chance of damaging the unit is at least as great as your chance of fixing it. At this point it's definitely pro time.

 

[NeoPTLD]

No foreign matters in-and-out.

 

[Paperdoc]

Sorry to hear that. In you place, I'd feel forced to send the unit to a pro service company to diagnose and fix. Not cheap, but hopefully less than buying a new one.

 

[NeoPTLD]

I threw it out. I'm going to get a surplus mechanical one.

 

[Paperdoc]

I've noted your other post. At least older mechanical constant-load beam balances can be worked on by mechanically-skilled people like us. I'd be hopeless trying to fix an electronic force-balance scale, myself, as you can see.