Banebots RS-775 Case Short

[Mike Betts]

Originally Posted by JB987

I realize you get what you pay for. The problem is we really have no choice when FIRST limits the brand/model and number of motors and the brand with the most choices has such poor quality product. We don't mind paying more for better product...just wish we had the choice to do so.

I agree... I'm not defending FIRST. I'm pointing out reality (as I see it).

I've been doing this for 17 years now... FIRST has always limited "the brand/model and number of motors" and I see absolutely nothing in the tea leaves predicting a change.;

[Mike Betts]

Originally Posted by theprgramerdude

Well, we paid $5000+++ to enter a competition that limits us on what we use to certain items. I'd prefer it if those items weren't faulty. Just sayin'

And in my opinion, you paid about $4000 too much...

[Jared Russell]

Just a warning...

Both RS-775 motors that we used on our competition bot that had been "fixed" by zapping became "unfixed" by the end of the first day of qualification rounds - the case shorts returned.

[Swampdude]

Originally Posted by Jared341

Just a warning...

Both RS-775 motors that we used on our competition bot that had been "fixed" by zapping became "unfixed" by the end of the first day of qualification rounds - the case shorts returned.

Is that what was disabling daisy?

[Jared Russell]

Originally Posted by Swampdude

Is that what was disabling daisy?

The jury is still out - we pulled off anything we suspected before crating and will be doing CSI-style forensics in the coming days and weeks to get this fixed in time for Philly...

[chris1592]

Not related to a case short, but some of our 775 gearboxes for our arm motors were starting to tear up at Florida. The casing on it would start to rotate around the gears and this was tearing the inner gears up, has anyone else had this problem or had a solution to it?

We tried using hose clamps, but they only stop it from rotating so far.

The black pins that hold it from rotating would just pull out or shear off.

[Karthik]

Originally Posted by Jared341

The jury is still out - we pulled off anything we suspected before crating and will be doing CSI-style forensics in the coming days and weeks to get this fixed in time for Philly...

Jared,

I would not be surprised if the RS-775 case shorts were causing your robot to die. We have had an endless stream of issues arising from these motors. Every single motor we have ordered from Banebots has come with or developed a case short. (Some of the motors were not tested until we had already used them. It's not our standard operating practice to test motors for case shorts prior to usage. We've now adapted our procedures to assume manufacturing incompetence.) Just in Pittsburgh alone these motors led to multiple trips of our main circuit breaker, trips of the motor breaker and possibly a fried cRIO. (The cRIO is definitely fried, but we're not 100% sure it's the fault of the Banebots. Although I have no idea why we're giving them the benefit of the doubt at this point.)

I highly recommend that any team who experiences weird issues with their robot to check the resistance from the leads to the case of their Banebot motors. Please spread the word to teams who don't read Chief. We saw a lot of teams in Pittsburgh who were having issues, and had no idea it could be traced back to a case short.

[JB987]

Warning seconded...we spent 3 days dealing with case short gremlins...days we could have used programming a two tube auto!

[Jared Russell]

Originally Posted by Karthik

Jared,

I would not be surprised if the RS-775 case shorts were causing your robot to die. We have had an endless stream of issues arising from these motors. Every single motor we have ordered from Banebots has come with or developed a case short. (Some of the motors were not tested until we had already used them. It's not our standard operating practice to test motors for case shorts prior to usage. We've now adapted our procedures to assume manufacturing incompetence.) Just in Pittsburgh alone these motors led to multiple trips of our main circuit breaker, trips of the motor breaker and possibly a fried cRIO. (The cRIO is definitely fried, but we're not 100% sure it's the fault of the Banebots. Although I have no idea why we're giving them the benefit of the doubt at this point.)

I highly recommend that any team who experiences weird issues with their robot to check the resistance from the leads to the case of their Banebot motors. Please spread the word to teams who don't read Chief. We saw a lot of teams in Pittsburgh who were having issues, and had no idea it could be traced back to a case short.

Karthik,

Thanks for the reply. Unfortunately, short of vigilantly changing out the RS-775s every time we detect a case short, I'm not sure what our best course of action is right now. We can drop from 6 drive motors to 4, but the roller claw absolutely requires an RS-775. Maybe non-metallic mounting hardware could at least help reduce the risk of a case short electrifying the entire frame.

[Don Wright]

We are also finding that the case short on our 775's come back after some practice on our practice bot. We will be checking the case on the 775's after every match as part of our after match system check.

We have also found that when this happens, the two banner sensors we have very close to these motors also exhibit the flashing green light occasionally which according to the manufacturer is output overload. This causes us to lose some counts on our lift. If we move our lift by hand, no Banner issues. If the cases aren't shorted, no Banner issues.

So, if you are using the 775's and are experiencing some funny signals from sensors, this could be a suspect. Just FYI...

Unfortunately, we have no way to isolate ours from the frame...unless someone has an idea for non-conductive bolts (other than plastic)...

[Al Skierkiewicz]

Guys,
What you are describing is a perfect example of motor current running through the Crio chassis. Beside the 775 case short, you likely have a sneak path somewhere else on the robot that ties the Crio chassis to frame. When a motor drives in one direction it may be driving the current through the Crio chassis, elevating the +24 volt common rail. This can cause various Crio issues up to and including reboots. Since the sensors are/should be tied to +24 volt rail, they also experience the same power supply issues. Using 24 volt solenoids should also show up some unusual problems in the pneumatics circuits as well.

[Brandon Holley]

Has anyone who has "fixed" their shorted 775s through the zapping process, and experienced the issue returning, tried to fix the 775s again? We have a couple of backups for our competition this week, but if it looks like we're going to be constantly susceptible to failure, it would be good to know if they are "fixable" again.

-Brando

[jwfoss]

2168 had various issues with the 775s on Friday at WPI, we checked both the 775s on our lift for case shorts and they were fine. After a few matches one was clearly hotter than the other and it had burned out the connected jag.

Checked a replacement 775 for the case short and it was fine, installed it, ran for awhile again and then the same problem. Ended up running the lift with only one motor the rest of the competition.

Guess we will be trying the zap fix and hoping for the best before CT.

I am extremely unhappy with the motors right now.

[OZ_341]

I think in light of this continuing issue that FIRST needs to relax the 2011 build rules and allow the replacement of Banebot motors with legal FP motors and/or CIM motors.

It is not ethical or safe to have a faulty motor as one of the alternatives in the KOP. FIRST should relax the rules enough to allow for the removal of all Banebot motors from 2011 machines. Teams designed their robots based on the assumption that these parts met certain safety and performance standards. If this was industry, we would be experiencing a recall right now.
This is what would be right. Why should FIRST or FIRST teams expect anything less?

[Don Wright]

Yes, we zapped, and the issue returned...zapped again...return...repeat...