Electronics > PCB/EDA/CAD

Could it be a bad motor?

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Ok, got a bit of a mystery at work going on... normally I can work these things out but this ones getting silly..
I repair robotic lights for events/concerts etc..
In this fixture, there is one effect wheel, which is moved via a stepper motor and uses a hal sensor at bootup to locate itself to its "zero" location..
The problem is that it doesnt seem to locate itself at boot...
So.. hal sensor changed, wiring checked, motherboard replaced.. scoped the 5v rail and it was  a bit messy so swapped the psu board.. still nothing...
I've traced the hal sensors signal as far as I can on the main board before it dissapears into a programmable IC and everything is fine.. but like I said, I changed the motherboard and that is irrelevant now.. But the main thing is that I have seen on the scope, the hall sensor reacting as it should through the entire wiring loom and through its isolator etc etc.
When I operate the fixture it works PERFECTLY, just not centered properly.... so technically the motor is working as it should.

Just looking for daft ideas as where else to look because today I pretty much exhausted the ones I can think of!!


Intermittent wiring loom perhaps?  Breaks in the wiring are pretty common in moving head fixtures.

Changed the magnet? Put it in back to front.

The magnet is eppoxied into its effect wheel...

And I traced the signal through the motheboard by turning the wheel so magnet was over and away from the hal sensor.. its a normally 5v, 0v with magnet .... and its operating perfectly...

You can see why Its got me scratching my head!! technically the entire system "works" and what I cant proove I've swapped out!


--- Quote from: David_AVD on November 05, 2012, 09:24:24 pm ---Intermittent wiring loom perhaps?  Breaks in the wiring are pretty common in moving head fixtures.

--- End quote ---

mmm possibly!!  I will admit I always test it with the lens straight up... yet it resets/self tests with the lens down towards its base!!


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