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Topic-icon FBL2360 - Quad Encoder Counting while motor stopped

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2 years 6 months ago #29533125 by methods

blake wrote: ... Can you share the datasheet or model of the encoder you've been working with?


I will check back in a week or three with a root cause analysis.

* Lousy Encoder
* Cold solder joints or poor connections
* Short to case somewhere? (forgot to check for that)
* Wire run too long, not twisted, not shielded
* Noise in the system... I was powering from a DCS 60V 18A power supply (good chance), Its a stiff bastard but smoke has come out of the back... so may be noisy now.
* Noise radiated from the RoboteQ plastic case (conductive paint?)
* Ground Loop or noise coming from Laptop RS-232 dongle
* Mechanically loose encoder wheel or pickup (vibrating.... tho this would show in more than the 1,1 case)
* Just plain bad luck


As for part numbers... if I get a chance to dissect I will post a part number if it can be found.

I will beat the drum I always beat for the new engineers out there... If you have parts coming out of China dont trust part numbers. Especially dont trust part number variants... like the 85C version vs the 125C version. If you are having product turn-key'ed out of China you need to unit test across your entire Voltage range, Load Range, and especially Temperature range. This is no BS. A simple Power-Up test or end of line test will result in great sorrow in your future.... because the counterfeit parts WORK (generally speaking) ... they just dont meet spec.

It is VERY common to find a part labeled high end (Fast, wide temperature range, stable) when in fact it is the lowest form of part available.
Example: OpAmps

So basic functionality at ambient and nominal works fine.
Crank the voltage up, run at max temp and max speed... see what happens.
Usually 8 or 10 engineers chasing their but for hours, days, weeks.....

You were warned ;-)

We dont turn key out of China. I love China and buy all sorts of things... like JST Cable Assemblies... but we source our parts from reputable vendors where pedigree can be established. Digikey, Mouser... these guys move a lot of parts and dont have time to fool around with bad stuff. Some of the others... end run suppliers... you never know what you might get, how it was stored, what it was mixed with, etc.

Your best friend if you accept the risk:
Octopart.com

-methods

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