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Author: Subject: Ohaus Scale Jumping back and forth
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[*] posted on 21-9-2019 at 19:07
Ohaus Scale Jumping back and forth

Hey all, so after 8 trustworthy years, my old Ohaus adventurer scale has started to finally slightly malfunction. It has now started to jump up and down after I tare it from -20 to + 20 mg bouncing back and forth between these numbers.

Has anyone encountered such an issue? What is the lifespan of a 0.001g Ohaus adventurer table top version mg scale, generally? Are they serviceable at all or would it just be worth scouring labx again for one?
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[*] posted on 22-9-2019 at 05:28
General approach ;

As the scales/balance seem to be mostly working ok,

1) what happens when there is a weight other than zero on the balance ?

2) check the power pack for stable dc supply
OR supply 12Vdc from a different source.
(I believe that it is 12 Vdc but check, and observe polarity if using a different supply)

3) it is common for electrolytic capacitors to degrade over 5 years or more,
open up the scales and look for bulging capacitors and look around the base of capacitors for signs of leakage,
look for overheated resistors etc.
you or someone that you know can help, replace all small electrolytic capacitors (note polarity)

4) whilst open check for circuit corrosion, dust, dirt, insect debris etc.

5) remove and replace all internal connectors where practicable
(they sometimes become loose or corroded)

6) reduce the illumination level of the backlight or if possible switch off or disconnect the backlight electronics
(that could be making interference due to worn out lighting)

7) disable the auto-tare / auto-zero / zero-tracking feature.

CAUTION : Hobby Chemist, not Professional or even Amateur
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[*] posted on 22-9-2019 at 18:03

Lifespan is mostly determined by where it's set up A scale can last for years and years in the right conditions, or less than a year in poor ones. I think 10 years is the example given as such in the lab book I have, I'll double check tomorrow. Could be more.

I can't give you advice, the only Ohaus scale I ever had was in worse shape than yours when I got it. Ended up in the bin:( good luck!
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