Electronic scales slowly breaking

[Maker]

Here's the error codes from the Furi website.

Not too helpful really, it could possibly be down to one of the resistors in the load cell drifting.

You could try measuring the output of the load cell with a multimeter, power it up and measure the voltage across S+ and S-, it should be pretty close to zero and increase with some load, not sure how high the circuitry expects it to go, probably no more than a few mV. Check E+ to E- too, should be some constant, "normal looking" voltage, you might be able to trace E+ back to a voltage regulator (Or the power supply) and determine what voltage it should be.

You could also desolder the load cell and measure each resistor individually. They're wired as a "whetstone bridge", under the epoxy there's four resistors, three normal and one designed to stretch and change it's resistance when the cell is flexed. They're wired like this:

Red and black leads are the top and bottom of the square, green and white leads are the left and right points. The resistors are probably all the same value, but if not, the ratio of R1 to R2 should be the same as R3 to R4, if one is miles out then it's probably shot, I don't think there's any saving it.

 

[voipio]

Agree. Look also at Vetek (https://www.vetek.com/precision-scale-600g001g-fr-h-bs600h-en/article). Vetek say that if you drop them an email, they will send you a manual for 'older versions'. Just tell them you have an FR-H and ask them for a list of error codes. Accidently neglect to mention that it is not a Vetek FR-H.

The vetek webpage has a download link for the manual, and in it there are details of how to calibrate, which may also work for the Ravencourt model. If you have a decent calibration weight, it might be worth a shot, since the procedure may also involve the performing of a zero compensation routine, and thus compensate for any zero drift that might have occurred over time.

 

[voipio]

From a how does this balance mechanism work point of view, looking at the design of the load cell, the pan carrier is screwed to the block on the right hand side of the load cell in the image, whilst the application of force by the pan is over the middle of the load cell assembly (which it doesn't touch). It seems reasonable to think that the induced moment resulting from adding mass to the pan will tend to rotate the right hand block anticlockwise, putting the strain gauge element over the right hand thinned section into compression, causing a reduction in its resistance. The whole thing becomes like a rectangle fixed at the bottom left, and being "leant on sideways". As a consequence, the strain gauge element over the left hand thinned section will be driven into tension, thus increasing its resistance. There may also be a similar strain gauge assembly mounted on the underside of the load cell. It may be that all four "arms" of the Wheatstone Bridge are active.

 

[knighty]

try storing it upside down (but not on the pan) when it's not in use?

see if whatever has drifted drifts back?