Through a series of unfortunate events, our jaguars controlling our CIM motors were wired incorrectly. V+ and V- was inserted into M+ and M- and vice versa. So the robot went crazy when we simply flipped the switch to turn it on. One jaguar caught fire internally. (Which we initially attributed to metal shavings).
When correctly wired, the jaguars still allow current to pass through them when their is no signal present, effectively landing us in the same situation were we had them wired incorrectly.
In addition, two more jaguars had their magic white smoke leave them.
In hindsight, with current running in the opposite direction unimpeded, plus the white smoke (and fire), I think all of 4 jag’s connected to the CIMs are ruined, even though they still power up.
Is this assessment correct?
How would I test the jaguars with a multimeter? I’m thinking about testing resistance across V+ and M+
Also, I’m thinking about opening the jaguars up to inspect the damage. Good idea?
One of our mentors is a power EE, but is out of town on personal business. When he gets back, I’m going to ask for his opinion on our situation.
first of all. you need new jaguars. thats for sure.
here we have 2 fried jaguars. but we were able to get few from a team that not playing this year.
know if you have a good electronics equipment (one of our sponseres have that). you can use the exact electrical digram (you can found them on the jaguar website). and then to find the exect “burned” chips…
we have done that. and we found out that it will cost us only 8$ to replace those parts (wich is 10% from the price of a new jaguar). the only bad part is that it will take the new chips up to 16 weeks to get here so we will have more working jaguars for next year
Also, we’ve learned the hard way to be carefull about going full forward to instantly full reverse on the drive system. We blew all four of our Jaguars when our programmers decided to “stress test” the robot before they had ramping code included. We did indeed find the week spot in the chain…the Jaguars.
Huh? I’ve NEVER seen that happen before. I mean, sure, there’s a lot of back-current that gets generated when you try to stop a motor quickly, but I’ve never seen it blow a Jag.
On a related note, though, at Champs a couple years ago we had some “ghost” in our drivetrain where if we didn’t do ramping code we’d brown-out the entire electrical system. Then again, we were using Victors and not Jags, but I don’t blame the Victors - we literally swapped out every electrical component (except the motors) and never got rid of it.
I made the same mistake my rookie year, except it was Victors.
Expensive mistake, but no team I have ever been on has ever repeated it. every electrical board gets inspected twice (at least) before being turned on.
I think the jags are done for, unless you do as reuven suggested in which case you could probably fix them (especially if you have an EE mentor). I wouldn’t consider them “competition worthy” if I were you, but they are definitely worth the effort.
wow, what wheels were you using, we have a pretty vicious gear ratio and we break traction and slide before we stall anything. we are 12.34 - 1 with 6 inch traction wheels.
This is key. Before we handed plugged the board in for the first time, we literally traced every wire and looked at each individual component as a group (and I checked it again myself between meetings) to ensure everything was wired properly. We managed to fry a Jag last year in the exact same way as described here… all because we replaced one (don’t remember why), plugged it in wrong, and were in a hurry.
Ditto, we made that mistake a couple of years ago and then got hit with it again this year (by a different team member who got excited and in a hurry as well). Triple check EVERY single wire no matter who is trying to push you faster. When they do politely ask if they are willing to purchase the new jags out of their personal account if something gets fried…
wow, what wheels were you using, we have a pretty vicious gear ratio and we break traction and slide before we stall anything. we are 12.34 - 1 with 6 inch traction wheels.
Our Jaguars blew with our six wheel drive robot with 6 inch Plaction wheels being direct driven by Supershifters. I don’t know if it was in high or low gear or some combination of the two. Anyway, not an unusual drive train. If it were just one Jag I’d chalk it up to random defects but all four blew after the stress test that lasted a minute or two. They weren’t set to brake mode, by the way.
Two years ago we killed two Jaguars doing nothing we could place. After working with the Luminary Micro guy who was on-hand at FLR for over an hour, I finally just said “Switch to Victors. They work!” We did, and they did.
We’re using Jags for our drive this year in the hopes that they do a bit better and the first generation, but at the least sign of trouble we’re switching to Victors.
Both Jags and Victors use power FETs in the motor drive output. These devices contain a internal diode across the source drain terminals and when voltage is applied to the motor terminals, the diodes will conduct. This high current is manifested by the smoke released during your power on. Unfortunately all four controllers are damaged. I am guessing these were Black Jags.
They were older gray jaguars. New black replacements are in the mail.
Our problems were probably two-fold.
Do the black wires in the power distribution board go to a “common ground”? The Jaguars were also hooked up to the board rather indiscriminately. The V+ and V- did not come from the same 40 AMP breaker.
The black leads are connected to power supply common. There is a layer (maybe two layers) of copper foil that tie all black WAGOs and the negative lead of the battery together. The black leads do not need to come from the same pair but it makes your life and mine a lot easier.
AMEN!!! We didn’t blow up any Jaguars last year, but our lifting mechanism kept on tripping the INTERNAL breaker on the Jag… the Snap-action wasn’t tripping, just the Jag… So we changed it to a Victor, and didn’t have a single problem the rest of the year… We even demoed our bot at the MO State Fair running about 40 matches in 8 hours… victors worked fine… Blew a Jag though!!!
Matt,
There is no internal breaker on the Jag. There is an over current sense that puts the jag into fault and disables the output for about 3.5 seconds.
