Re: Banebots RS-775 Case Short
 

No, you're fine. I was a bit dense.

I was caught off guard by your dry sense of humor.

Re: Banebots RS-775 Case Short
 

It's just about time for some testing. Perhaps as soon as tonight. :D

Fresh out of one of my FDM machines! ;)

Re: Banebots RS-775 Case Short
 

That looks like fun. What's the polymer you used?

Re: Banebots RS-775 Case Short
 

ABS (Specifically P430) If you want more information about it check out stratasys.com or dimensionprinting.com

Re: Banebots RS-775 Case Short
 

Looks good! Are the spur gears a press fit?

Re: Banebots RS-775 Case Short
 

No slip fit with a set screw.

Re: Banebots RS-775 Case Short
 

Gearbox looks fantastic. Now I want to get our 3D printer running. I could just as easily lasercut some plates and throw a couple standoffs in there though.

Re: Banebots RS-775 Case Short
 

Same here. :) Ours should be ordered and coming in within the next 2 months. Too bad it'll be too late for this 2012 build season.

Re: Banebots RS-775 Case Short
 

We will not be using RS-775 motors this year.

It's a risk we just can't take. However, we are using 550 motors for sure this year.

-Nick

Re: Banebots RS-775 Case Short
 

Same with us.
Just need some of those p60s gearboxes...

Re: Banebots RS-775 Case Short
 

This would be sweet.

Re: Banebots RS-775 Case Short
 

Banebots called us today and asked for info on our testing, results, and motor info (printed on motors).
We found several so far that have the case shorts, yet when in use on our shooter with the CIM-U-Lator, have seen no ill effects as of yet.

Since they are willing to solve the issue and send us new ones, we plan on using them.

Re: Banebots RS-775 Case Short
 

This is a very sad day. I had high hopes for those 775s. I heard that all that was in needful in this case was to electrically isolate the motor can.

I have access to a 3D printer and some mad CAD and engineering skills, so... ...I thought I was all set.

But, two things disappoint me.

First, that what appears to be a good motor is really a ticking time bomb in many cases.

Second, Banebots. I know that they are a small company. But they just don't seem to understand what it means to a team when a their hearts are broken by something outside of their control, all the more so when the problem was known by the source of the problem.

BB has had a year to try to get to the bottom of this issue. Sorting motors is better than nothing but it hardly seems like enough given the severity of the problem.

Banebots has been a great supported of FIRST. I love a lot of their products and I love their prices (if you don't count the cost of poor quality biting you in the back when you can least afford it).

But, I am disappointed.

Joe J.

Re: Banebots RS-775 Case Short
 

This is how arms races begin.

But then I got to thinking. Brushes? We don't need no stinkin' brushes! (If only we had a speed controller that would work.)

It would be sweet seeing what you come up with, when mass-producability is thrown out the window. (Maybe not quite so sweet trying to beat you at your own game, though....)

Re: Banebots RS-775 Case Short
 

I've slept on this problem. To use the BB775s or not to use them?

I really want to use them because they should be a great motor. I think that isolating the case (from anything, including other BB775s) will limit the damage to that one motor. If I am using 2 in parallel (e.g. in a large arm application), unless both fail in the same match, I can limp through the match with only degraded performance as a result.

But... ...I don't like to go this way unless I have some way of detecting the onset of the problem and changing it at the first sign of a problem.

Has anyone tried monitoring the voltage on the case live while the robot is in action?

I am thinking that I could have put connect the case to a resistor network. For example, I could put two relatively high resistors in series between the battery and ground and tie the case to the middle of these and monitor this voltage. This monitor voltage (i.e. the case) would sit at roughly 6-8V (1/2 battery) unless a short starts and then it would start going rail to rail 12V - gnd - 12V - gnd - ...

And this is when I would replace that motor.

What do people think of this scheme?

Joe J.

Re: Banebots RS-775 Case Short
 

Joe,
Anything less than 10K is likely going to get the Crio upset at some point. Don't forget that the voltage polarity on the case will reverse when the motor direction reverses. It will also have the speed controller switching component and any brush noise that might be induced as well. You monitoring needs to compensate for high noise and 15kHz for the Jag and 150Hz for the Victors.

Re: Banebots RS-775 Case Short
 

While this is true for the relative polarity between the two motor leads, it is not so for the can. The can will be shorted to one or other of the brushes*. The voltage on the can will then be pulled hard to Vbatt when that bit of the winding touches whatever side the Jaguar is holding to Vbatt and it will be pulled hard to Gnd when the motor turns such that that same portion of the commutator is touching the side the Jaguar is holding to Gnd.

As to noise and Jag PWMing, I think this the least of our concerns. A simple filter should make that bit go away.

As to the cRio getting upset with lower than 10K, I don't see how this comes into the picture.

Some ascii art:
Vbatt
...|
100 Ohm
...|
Motor Case -- RC filter (band pass) -- cRio Analog Input
...|
100 Ohm
...|
Gnd


The band pass should remove the DC offset of 1/2 Vbatt, allow the rail to rail swings (say 1200-18000 RPM motor speed so allow 20-300Hz or so), and remove the Jaguar PWM and other junk (1000Hz and above).

I am not a EE but it seems that there may be some room for a solution in that space.

Joe J.


*well, it will be shorted to both because the motor windings connect the two, but odds are the short will happen with the wire length to one brush being much shorter than the other so it will act like a short to that one brush.

Re: Banebots RS-775 Case Short
 

Why worry about it when the robot is in action? You can't stop the game and do anything about it anyway.

Monitor the resistance between matches, change them out if it reaches a value bothers you.

Re: Banebots RS-775 Case Short
 

If power to the failing motor is cut then it may save a cRIO reboot and thus the robot will remain mobile for the match instead of being dead in the water for 30-60s.

Re: Banebots RS-775 Case Short
 

If the 775 is completely electrically isolated (via both the case and output shaft) through plastic mounting plates and either acetal gears or timing belts, will the cRIO ever actually reboot if a motor starts to go bad?

Re: Banebots RS-775 Case Short
 

I recall somewhere way back in this thread that at least one team had an issue, in rare instances, with a pair of 775s shorting together , instead of through the frame. The current draw would tank the robot's voltage and cause a reset. This may not be an issue depending on your exact setup.

Joe said "I think that isolating the case (from anything, including other BB775s) will limit the damage to that one motor." which might be an issue if multiple motors are failing/failed and short together.

I guess I skipped a few details in my thought process :p

Re: Banebots RS-775 Case Short
 

Joe,
The Crio chassis is tied to the negative lead of the battery. The power lead to the Crio is not sufficiently low impedance to prevent (nor is the boost regulator capable of overcoming) a disturbance in the power to the Crio. If anything on the Crio finds a frame fault including the Crio chassis, considerable current (not full motor current of course) will then flow on that negative wire. It appears that in the motors opened last year, the majority of shorts occurred between motor windings and the armature. How close to one end of the winding that fault occurred is anyone's guess. A few appeared to be stray solder that migrated between a brush assy and the case. Another reason for concern is the possibility of two robots with electrical faults becoming engaged with current flowing between frames.
While it appears that the Crio can operate at less than 19 volts, the spec is to operate above 19 volts input.

Re: Banebots RS-775 Case Short
 

We are not using the Banebots 775 motors.

Re: Banebots RS-775 Case Short
 

I thought the chassis of the cRio was tied to 24V.

Even if on one robot the chassis is connected to 12v and on the other it is connected to gnd, nothing would happen if these two robots touched each other. Sure, you'd be able to read 24v between the (-) terminal of the first robot and the (+) of the second if you stopped the match and walked out there with a voltmeter, but there is no complete circuit for current to flow through. Both the (+) and (-) of the same battery would have to be connected the different parts of the chassis and/or frame for any current to flow.

Re: Banebots RS-775 Case Short
 

If you don't mind me asking, who is "we"? If 254 isn't using them, that really says something, because I know they do their homework when it comes to motors.

Re: Banebots RS-775 Case Short
 

254. I'm pretty good about updating my current team info.

Re: Banebots RS-775 Case Short
 

This is actually one of most common myths in FRC, perpetuated in a blue box in the rules each year. The real reason we isolate our frame is to allow the system to survive single-fault wiring failures.

This is similar to the way the PD's prototype big brother detected chassis faults, except we pushed an active signal instead of using a resistor divider. The control system would be fine with 100 Ohms, but that'll burn three fourths of a watt. I'd bump up your impedances into the 5-20k range. You're signal quality will be unaffected but it can be smaller and safer.


No. A fully isolated but faulty 775 will not have an adverse impact on any portion of the control system electronics. I do not have any information as to whether or not this fault will have an adverse impact on the motor itself.


To the negative lead through a fuse and a self-resetting fuse. If bonus current is sent through this path, the two race to see who will blow first. The single-use fuse rarely wins, but can go with repeated abuse.

True. This is another myth that used to be in a blue box.

Re: Banebots RS-775 Case Short
 

Erik,
I have to disagree. While the fuse internal to the Crio is meant to protect parts of the internal Crio electronics, electrical faults on the robot can cause real voltage drops across the #18 wiring used to feed power to the Crio. This is well documented over the past two years irrespective of motor issues. With these faults current merely flows through the chassis of the Crio to the negative lead and out the power connector.
Isolated (electrically) frames have been part of the rules to prevent robot to robot electrical faults from causing sparks and fire on the playing field. The potential in this scenario is the ability to provide up to 24 volts at high current, through parts of the frame and any wiring that might be in the circuit. Anyone who has been around more than a few years remembers the spectacular displays, smoke, hot (incandescent) wiring and yes even some flame that occurred prior to the inclusion of this rule.
Jason, the common myth is that robot to robot contact usually includes not only the robot frame but appendages or robot parts when tipped over, which have reached inside another robot. This is the second or third path that most people forget. In some cases, current will continue to flow even after the robot is disabled and the main breaker has been opened. It is why inspectors are so critical when checking the insulation on all electrical connections.

Re: Banebots RS-775 Case Short
 

Al, Eric's post was rather long, and it's unclear which part of it you are disagreeing with. Would you please quote the portion you are disagreeing with?

Re: Banebots RS-775 Case Short
 

I could only disagree with Eric's response to my quote and answer Jason's question.

Re: Banebots RS-775 Case Short
 

Ordered either late on the 16th or on the 17th. Received my order yesterday. Shipped on the 6th business day, arrived 2 days later. Beautifully packed, good fit and finish on all parts, no shorted motors (out of 3 775s). Looking forward to trying it out. :)

Re: Banebots RS-775 Case Short
 

I'll add to this -

I ordered 3 775s and some 4:1 planetary gearboxes from BB on 1/10. Received the whole order, well packaged, on 1/13. All the motors passed our EE's load testing, and now they're being used in test beds with the programming team.

For me, BB has stepped it up quite a bit this year. No bad surprises so far.

Re: Banebots RS-775 Case Short
 

So you are saying

1) The voltage polarity on the case will reverse when the motor direction reverses?

and

2) Electrically isolating the robot frame does not allow the system to survive an armature-to-case short in a motor?

If I've misunderstood, could you please clarify.

Re: Banebots RS-775 Case Short
 

I have been following this thread all season, ( of course after placing an order of what we could afford (2 775 BB and 775 BB gearboxes). If and maybe when we receive them, and they do have case shorts, living in a place where 2nd day air means 2 weeks (Really not exaggerating, unfortunately), shipping back for a refund and maybe working BB is not an option.

What I have gathered is that:

Run a 12 Volt across the each of the leads to the case and hope for the best?

Mount motors and such to lexan/Derlin if all else fails.

Anything else?

Re: Banebots RS-775 Case Short
 

No,
I disagree with a statement of myth. At the time that faults were first noted on FRC robots, the IFI control system was being used. It does not have a conductive case. However, robots with any electrical faults to the frame could under certain conditions cause current to flow between robots.

The polarity of the voltage present on the case of a failed motor can change depending on where in the motor the failure occurs. If the fault occurs with internal wiring/brush assy and the case of the motor is tied to the negative lead of the battery (or near that potential) when operated in one direction. Then a motor reversal in this case is likely to put the case at near the positive lead of the battery. If the motor winding alone is the source of the fault, then the polarity on the case will change with rotation and will vary with duty cycle supplied to the motor. There are other variables as well depending on the nature of the fault, such as in a motor where the commutator is bridged by solder splash or two windings are shorted together.

For those just reading the thread and those actively participating, please remember that motor failure is a common occurrence in motors other than the Banebots 775. Mishandling, improper mechanical design and stray metallic debris all contribute to these failures every year. While a failed motor in and of itself may not keep you from competing, other wiring errors will add to the fault and affect your ability to play. Consider for instance, a failed motor on a robot with an insulated Crio but a camera that has not been mounted with the same care. The camera and wiring, and the PD power supply will be affected.

Re: Banebots RS-775 Case Short
 

I'm trying to clearly understand what your intended meaning is.

"cause real voltage drops across the #18 wiring" strongly implies that you mean due to additional current through those wires caused by the fault condition. Was that your intended meaning?

Re: Banebots RS-775 Case Short
 

Yes

Re: Banebots RS-775 Case Short
 

I don't see how a motor case short can cause an increase in current in the cRIO negative power lead if the cRIO chassis is electrically isolated from the robot frame.

Perhaps someone could post a sketch showing the current path.

Re: Banebots RS-775 Case Short
 

This isn't the appropriate thread for this, and I'd appreciate if this side bar could be split off.

In a double fault scenario, additional current can flow from the motor, through the chassis, into the cRIO frame, through the cRIO's fuse, out the connector, through the return wire, into the PD, through the PD's self-resetting fuse, to the negative return of the battery.

The question is a matter of timing: Which protection cuts out first? The four in play here are the cRIO fuse, the cRIO power supply undervoltage lock out (UVLO), the PD's self resetting fuse (PTC), and the return wire experiencing a rapid gaseous state transition.

My claim is that the PTC is doing what I designed that circuitry to do, and that it is cutting out first. It heals when the fault clears, and then the cRIO begins to reboot, as my fellow NI engineers designed it to.

Re: Banebots RS-775 Case Short
 

You need to think of the Crio power supply wiring as a resistor. While the entire motor current will not flow in the negative lead of the Crio (if it is tied to robot frame), what current does flow will affect the power input at the Crio. It only has to drop enough voltage to cause the Crio to reboot. When that occurs, all Crio output is disabled and there is no current flow through the motor.

Re: Banebots RS-775 Case Short
 

We both agree that that wiring link is resistive and that the voltage it develops does eat in to the 24V supply's margin. We disagree on how much voltage is developed, how much margin the supply has, and how quickly the PTC blows.

The current necessary to cut out the entire margin budget is orders of magnitude beyond the points the protection devices cut in.

The PD schematic and design package are available for review on usfirst.org . If anyone is interested, please run the math.

Re: Banebots RS-775 Case Short
 

Eric,
All we are really worried about is the voltage change at the power input to the Crio. There does not need to be a trip in the PD. It is like adding huge amounts of ripple in linear power supply. All that has to happen is for the power at the Crio to upset the internal power sense and the Crio reboots. Considering that switching PWM is a significant component in the current in this line, the internal regulators of the Crio likely give up pretty easy. I suppose it is also possible that the 24 regulator gets fooled into restarting but I really doubt it. Added to the switching, you have sometimes huge amounts of RF generated by the brushes and switching, particularly in the Jag.

Re: Banebots RS-775 Case Short
 

Al, I'm trying really hard not to be rude, but the math simply does not hold up. It looks like we'll have to agree to disagree unless you can provide evidence to support your theory that the UVLO fires before the PTC. I still believe it is behaving as it is designed to and how the math indicates it must.

Don't get me wrong, I understand what you are driving at. It is a perfectly valid theory, it just doesn't hold up in this situation. For this system, the current/time profile to trigger the PTC is much much smaller than the current/time profile to trigger a UVLO: On the order of 100-750x smaller, depending on the shape of the pulse.

Re: Banebots RS-775 Case Short
 

Just got our 550's and 775's. Not sure if I should be scared or not...

Re: Banebots RS-775 Case Short
 

To what are you referring to as UVLO?

Re: Banebots RS-775 Case Short
 

Under Voltage Lock Out. This is the generic term for a processor or device shutting itself down when it doesn't have sufficient voltage to guarantee correct behavior.

Re: Banebots RS-775 Case Short
 

Eric,
The PD is very well designed and works very well. Without any valid data I cannot tell you which trips first since the effect is the same, that is Crio reboot. With the relatively low impedance of the motor wiring back to the PD compared to the higher impedance of the Crio power wiring, it would appear that the majority of the fault current would flow back through the motor wirin when we first observed this fault, we were prototyping with a small motor that we had removed from a battery operated vacuum. The motor case was intentionally wired to one of the wires. I don't think the motor drew more that 10 amps.

Re: Banebots RS-775 Case Short
 

An update from 222. Our shooter using 2 775s has been working flawlessly. We have been periodically checking the 775s to make sure they check out ok. We've put about 60-70 shots through it between last week and this weekend. So far so good.

Re: Banebots RS-775 Case Short
 

Same here! 256 has had no problems with our 775's.

Re: Banebots RS-775 Case Short
 

On a more positive note, I received 6 RS-775-18's today from Banebots. All test out fine!

Re: Banebots RS-775 Case Short
 

2175 has had 775s chugging through some shooter tests that we "borrowed" from last year's robot, and they've had no problems so far. Haven't done any case short tests since we first got them last year. However, because there are so many other motors available, we're going with 550s on the competition shooter just to avoid the headache other teams have experienced, and keep the 775s around for other testing. The 550s are just 20W less powerful than the 775s, and we think we can get by.

Re: Banebots RS-775 Case Short
 

Although I doubt you'll be running them at max power for any length of time (at least I hope not), let's do some numbers anyway just for grins:

at max power of 251 watts, the 550-12 generates 267 watts of waste heat.

at the same power output of 251 watts, the 775-18 generates only 141 watts of waste heat.

the mass of the 550-12 is 218 grams. the mass of the 775-18 is 337 grams.

the ratio of waste heat to mass is therefore

550-12: 267/218 = 1.22

775-18: 141/337 = 0.42

Re: Banebots RS-775 Case Short
 

Yep, these are going somewhere where they're seeing mostly intermittent duty (not at max power when free wheeling, probably powering shooter down when collecting balls), so we aren't concerned about the heat. But it's interesting to see that comparison.

Re: Banebots RS-775 Case Short
 

Has anyone received any 775s recently who can comment on the condition in which the motors arrived?

Re: Banebots RS-775 Case Short
 

We received 12 RS-775-V18 motors.

Test ran unloaded for 20 min
Checked for Case Short - none

Then we started using one on the shooter.. After some testing, case shorting was detected. That motor is begining to degrade and run at a higher temperature. We plan to use it till it drops. We want to develop a replacement and reliability plan for the motors in this application.

We implemented modifcations to improve cooling of the motor based on of the other threads. These included a spacer between motor and the CIMulator to permit air flow into the motor and cooling fins on the motor case.

Re: Banebots RS-775 Case Short
 

Team 907 has just received two RS-775-18's
One has a case short.

so, 50% failure rate
:mad:

Andrew Paul
907 Mentor
EYCI

Re: Banebots RS-775 Case Short
 

re motors coming from factory shorted

Wow. Even after last years feedback, the manufacturer has still not solved the problem. Worst still they apparently are not even doing simple QA tests on them before shipping. We (or Banebots) need a new motor supplier. I have 6 of these on order and I can't see how I can risk using them.

Re: Banebots RS-775 Case Short
 

As Banebots has pointed out, they do run tests on their motors before shipping them out and advise any teams who receive bad motors to contact them asap. It's my opinion that motor defects upon receipt are the result of poor packaging (the shipment of 775s we received yesterday had pieces of broken Styrofoam, which I assume was there hold the 775s stable during transit).

We received a shipment of 4 775s yesterday, none of which had case shorts and were fully functional.

Re: Banebots RS-775 Case Short
 

This problem has been notoriously intermittent, and I don't know of a good way to know whether a particular motor doesn't have the issue. Detecting a case short is a certain way to know that there is a problem, but not detecting the short doesn't mean that there isn't a problem. Rotating or jostling the motor can hide or expose the defect.

I'm of the opinion that the "case-zap" method doesn't fix or clear anything, it just shakes things up hard enough to push the defect back into hiding for a bit. It can then pass bench testing until something else causes it to express again.

I'm willing to believe that Banebots is performing best faith QA, and that the defect is too finicky to be caught by their testing. My suggestion is to teams is to treat all of these motors as defective regardless of testing and isolate them appropriately or switch to a different motor.

Re: Banebots RS-775 Case Short
 

Team 3135 placed initial order for a pair of CIM-U-lator=>775 gearboxes recently (on Feb 1st)), along with a total of four 775 motors. Because of the internal shorting problem, we wanted to have spares.
Expecting at worst maybe one in four to test bad, our order arrived today with THREE SHORTED MOTORS (zero ohms) out of four. We are bailing out on using the 775 motors for ANYTHING EVER AGAIN. I hope we can get a replacement pair of DUAL 550 CIM-U-lator gearboxes shipped ASAP. Banebots may be testing these 775 motors, but if so, USPS is killing them in transit. Packing was adequate but not very good considering the known issues. The motors should have been rolled up with multi layer bubble pack surrounding them, and they were not.

FOLLOW-UP - GOOD NEWS
Banebots agreed to send us by overnight ship two back plates that would let us convert the CIM-U-llator gearboxes over from RS775 to RS550 (single or dual). Right now it's only for lack of the big gears and output shafts that is slowing down CIM-U-lator deliveries, but the aluminum plates are in stock. So, this lets us use dual 550 motors instead of 775s.
So, they sold us the two back plates for the price of one complete CIM-U-lator, and 3 extra mounting kits were also included.
BTW, for those waiting for 550 CIM-U-lators to ship, they would not move us to the head of the queue to swap a single 550 CIM-ulator gearbox for our one unusable 775 gearbox simply because of the three shorted 775 motors, even though we offered to overnight return the one of the 775 CIM-U-lator to get a 550 replacement. They understood that we no longer trusted using 775 motors, even free replacements, so, instead they proposed getting us the 550 backplates .
With this compromise, we are happy and feel taken care of by Banbots.

-Dick Ledford

Re: Banebots RS-775 Case Short
 

I am glad to finally hear a few positive comments about Banebots in this thread. The RS775 has been a problem for everyone using it in the FIRST applications, but that's the way things work when you use a part in something other than its intended application (it's probably intended for harbor freight battery-operated drills, where you shouldn't be surprised if you lose part of a winding and a short to the motor case has no other negative effect). Banebots has been responsive whenever we have contacted them, and I like their planetary gearboxes. The 64:1, 16:1 and 4:1 gearboxes differ only in their ring gear length, so you can buy some 64:1 gearboxes and some shorter ring gears before build season starts, and be ready for most situations with very little money spent. I haven't found similar functionality for similar prices elsewhere.

Re: Banebots RS-775 Case Short
 

For a robotics application, non-FRC, my team got several 775-18 motors (the 775-12 is being discontinued). Tests are pending for shorts; they will be used in a critical system. Yes, we made sure to get spares. (And the packaging? Motors in styrofoam, and packing peanuts filled the rest of the box except maybe where the P60 gearboxes were--USPS Priority Mail box.)

Re: Banebots RS-775 Case Short
 

Banebots should be doing a dielectric test with a HiPot tester, not merely a resistance check with an ohmmeter.

Re: Banebots RS-775 Case Short
 

I believe in giving credit where credit is due - especially when I pointed out banebots flaws so often before.

It seems they're learning. Returns are easy and aren't argued at all. The banebots we've gotten (8) have not had any case shorts.

I'll be retesting the ones we've been running on our shooter tonight- they've run for probably 20-24 hours of actual spinning time and if they haven't developed shorts now, they probably never will.

So, right now I'm giving banebots a golf clap for having improved their return mechanism, and seemingly doing a pretty fair job of quality checking their product.

In point of fact, I've had as many problems with AM products as I have with banebots this year. Of course, AM has so much good will built up with me they could probably just forget to ship something and I'd give them a pass!

Re: Banebots RS-775 Case Short
 

So do I, but I think you missed my point.

Banebots claimed they are doing 100% testing of the 775-18's.

Since teams continued to receive case-shorted motors after that policy was implemented, it's a strong indicator that they are not doing HiPot testing, which would be the appropriate testing for this type of problem.

Re: Banebots RS-775 Case Short
 

Just to confirm, the RS-550 doesn't have the same problem?

Re: Banebots RS-775 Case Short
 

It's never been detected, to my knowledge. Just the RS-775 (I think just the RS-775-18, to be more specific).

Re: Banebots RS-775 Case Short
 

We had a 550 with a case short. Don't know if it came that way or if the short developed from over heating. Our shooter is driven by two 550s in a CIM-U-LATOR that's been modified to allow air flow to the vents on the motor face. I've been told that the motors got pretty hot during one extended practice session, but continued to work fine. Then at our first competition, we failed the continuity test during inspection. We traced it to one of the 550s.

Re: Banebots RS-775 Case Short
 

Has anyone else had an issue with the PG-71 gearmotor's 775 shorting?

Re: Banebots RS-775 Case Short
 

We've had no such issue, but the only PG-71 we have is the one we received from the KoP; we found Banebots/FPs to suffice for all our motor needs.

Of the 10-odd 550s and 775s we ordered this year, none had case shorts. Whether case shorts will develop is something only time can tell.

Re: Banebots RS-775 Case Short
 

We have the same deal. All Banebots motors, 550s and 775s, work beautifully, and have been throughout the whole build season.

The only problem we've had with our order was when someone accidentally smashed the shaft of our CIM-U-LATOR gearbox somehow (I think it was a freshman).

Re: Banebots RS-775 Case Short
 

The testers report that they're all good motors, and they've been run-tested. I'll report back if we end up with any issues.

Re: Banebots RS-775 Case Short
 

How did the testers test them? Just with an ohmmeter?