Neo550s acting weird

So, got weird behavior… it seems to have a dead spot. It runs perfectly open loop, but feedback only works if doesn’t start with the “O” up.
The phase connectors are all fully pushed in and have the expected small back and forth range. Encoder connector looks fine.

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Sounds like a single phase could be burnt / dead to me…

Visible as startup issues from specific locations. Generally from stalling and exceeding current limits in high load or under geared, I had a software limit of about 45 amps last year but we still burnt At least three. (Students replaced them twice without telling me, so we didn’t root cause in the lab and got bit again at competition…)

I hadn’t contacted Rev about it because it’s pretty clearly our own fault

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I wouldn’t use a limit higher than 20A on a 550.

Actually, I retract that, when we had a dead phase we could reproduce startup/spin-up issues from specific locations in open loop, under load.

If your open loop testing is also no load, then I’d say dead phase is still possible.

Seems to be a bad SparkMax… tested with a known good and it worked. Argh!

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Oh, and open look testing is under load.

Any dead phase could be in the controller, FWIW.

I wonder if I can figure out a way to test for this. Hmmmmmm. Thinking about current transformers… Mwah, ha, ha!

This behavior is very consistent with a touchy Anderson Power Pole connection.

Technically there is still the possibility that the connectors on the original MAX were causing the issue. From your original post it sounds like you read our Anderson Power Pole guide, but it wouldn’t hurt to double check the original connections.

Please send us an email at [email protected] if you haven’t already, especially if double checking and re-crimping the original controller doesn’t resolve the issue.

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I get similar weirdness on a different motor, and every motor I try on that spark runs rough. I set up a rig with current transformers and got funny motor current. Those are red/green LEDs, so it’s very weird that we get solid red and green sometimes. That’s telling me that the bridge is half fried!

@dyanoshak I will pull the controller connectors out of their shells when I can get at them again…

Its looking more like a damaged SparkMax; the wires on the SparkMax look well crimped, and I got similar behavior on multiple motors. Not perfect, but certainly good enough, and fully inserted!
I’ll post more as I learn, and I’m also going to bash together NEO tester 1 shortly. image|199x186

It is very hard to see the crimp quality on the white and black wires with the low resolution photo. However, it looks like there are extra strands on the white wire that can be interfering with how the contact sits within the housing, even if it is fully inserted. It also looks like there are strands within the gap between the large and small flaps of the contact on the black wire, which can also interfere.


What I have seen personally and with many other users, if the contacts aren’t close to perfect, it can greatly affect how the contacts mate in the housing.

Some critical tips to ensure the best possible Power Pole crimps:

  • Strip only enough wire that is needed for the big flaps. No wire should sit in the gap between the big flaps and the small flaps.
  • Do not solder PP45 contacts. Solder can wick into places that can interfere.
  • Inserted contacts should have some “wiggle” or “give” when inserted in the housing. This allows for the spring to do what it is supposed to do. If the wire you have has especially thick insulation, this can sometimes affect the amount of play in the housing.

I’m not discounting that there may have been something damaged within the MAX, but I want to help completely rule out a connector problem.

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