I don't know what it is with the sabertooth controllers, but I've seen many end up breaking like that.

Sorry, I don't manage my LinkedIn account.

Basically they said it's because of a ground loop caused by adding the reference ground between the 0v and the controller when the Sabertooth and controller are powered from the same source.

I have a new one coming and they have agreed to try and fix the old one free of charge. So can't fault that for service.

My thought is that it would be a fairly common situation and both the EZB and Sabertooth documentation specifically mention the requirement for a ground reference but no mention of the risk a ground loop could cause.

How are they able to determine a ground loop? That would mean you have resistance on the common ground between devices: https://en.wikipedia.org/wiki/Ground_loop_(electricity)

I do not believe the person you spoke to has experience in electronics. However, you are getting it repaired, but I am not confident that is the case.

You see, absolutely everything in an electronic circuit requires a common ground. This is irrelevant to how many power sources there are. There can be one power source or sixty-five million power sources - common ground is mandatory. If a common ground were not implemented in the circuit, the components on the circuit would indeed not function correctly and most likely be damaged.

A common misunderstanding is associated with what counts as ground. The ground is a point in the circuit designated by the circuit designer as the point against which all circuit voltages are measured. The ground can also be known as 0(zero)V. The ground is often but does not have to be the negative pole of the supply. Ground could be the positive pole of the supply or the midpoint of a split supply. The ground is not a point on a particular component; for example, the battery's negative (or positive) pole is not ground.

So if they're telling you that there should not be a gnd connected between the sabertooth and ezb controller, they should not be in the position of advising customer support.

I totally agree that's why I was looking to take this maybe to some option of PM but there's no Private message function on Synthiam (Future option maybe) to share their responses.

My experience with ground loops usually is in relation to inducing interference in RF lines, I work in Comms and Nav systems.

I don't see how this could have contributed to the failure in the DC system, and the circuit I have. My concern is that I follow their advice and the new controller blows.

My only other thought was that the motor cut-off switches in some way contributed to this, as during power up I had them in the off (open position) it allows me to freewheel the droid with the battery disconnected and not worry about the sabertooth regenerative system. However, that's a fairly common setup from what I have seen from R2 builders.

As I mentioned in the first post I'm really at a loss as to what caused this.

Sorry I can’t help people individually, or I’d never have time to breath haha

if they say it’s a ground loop, check the resistance between the sabertooth’s gnd and controller gnd. Show them there’s no resistance. Explain it must be a defective controller.

it would also be useful if you knew what component was damaged. That would tell us what broke and therefore lead to what could have happened to break it (or prove faulty component)

Lol, understood. It was mainly as I don't like talking negatively about a company in a public forum, and a was nervous this may come off that way.

All of the bucks pass through ground so they are all at the same potential, same as the Sabertooth. It all makes no sense to me.

I've posted up the details in the R2 builders club and see what people say, I know others are wired the same way with no issues.

Wow, what a cool robot! I love it! I've been off line this past week with no power or internet due to Hurricane Ian. I live in Cape Coral, Fl and just got back service. When I logged back on to this forum your post blew my mind.

I'm very interested in your struggle to overcome your issues. I've used a lot of Sabertooth motor controllers with and without a kangaroo and this it the first time I heard of one blowing up. DJ says he has knowledge of this happing to others and I sincerely believe him. His guidance in these matters can be trusted. You're in good hands. LIke DJ, I have a hard time believing a ground loop could cause this. Most likely a weakness in the Sabertooth or some component attached to it. I'd first point to the Sabertooth being faulty. They have protection built in to keep power issues and shorts from killing them and keep this from happening. I hope you find the cause and report back to us. I've always felt that the Sabertooth family is built like a tank and I never worried about this kind of thing happening. Until now.

You mentioned you were talking to the Robotshop. I assume you also contacted DE since you say someone is repairing it for free for you. Which company did you get the ground loop info from? I've contacted DE's customer service many time and have always found them to be very responsive, quick and helpful.

Good luck with resolving your issues. I'll keep watching this thread with much interest.

Hi Dave, glad things are coming back online for you, we were just hit by Fiona the other week. Luckily only without power for 10 hours, some are still out.

I'm interested in how your sabertooth is connected with regards to power. Do you use an ezb or auduino, how are the components wired?

My diagram is below hopefully pdf to jpg doesn't lose too much quality.

Robotshop just let Dimesion take over and they supplied the recommendation and the offer to repair.

I've checked all other components and wiring now and everything works and nothing seems out of spec. Everything I've read seemed to indicate that these units were pretty bulletproof, apart from cross connections or driving thr motors with the battery out.