i swapped the fuse with one of the fuses from my other ezb, unfortunately without success. (but good to know there is one)

I unscrewed the top... and that's where the burnt smell comes from. Nothing can be seen visually, but I guess I have to put up with it.

The question is, what can I do to make sure this doesn't happen to me again?

Am I on the safe side if I use the lipos individually?

It’s always safer to use lipo individually. The ezrobot ezb v4 was designed with lipos. And lipos are just batteries anyway, so it doesn’t matter what kind of battery.

You’d have to figure out what went wrong, so it doesn’t happen again.

I have seen low-cost/quality servos break the wires inside the servo and short. Or, the power could have been applied in reverse accidentally.

You can always try reaching out to ezrobot support and see if they can help you. It’s rare that a circuit would break entirely without any partial function. That might mean the power supply is damaged if that’s the case. You could try applying 3.3v to the ADC ports and see if it comes to life.

Do you have power in the power pins when connected to a battery? Or is there continuity between the power supply and power pins?

Otherwise, there are other ezb options, such as Arduino, and it’s more cost-effective. The esp32 could be used with an SSC-32 servo controller.

The only trouble is piecing parts together can end up as costly as an ezrobot ezb.

Wonderful information from all here. Thanks for the guidance and tips. I'd like to add a few practical and personal thoughts;

I've struggled in the past with the same issues you have @Knusel. Power brown outs, burnouts, quirky script writing.  I've also burnt up my share of components and devices. It sucks but happens. Sometimes I didn't even know what I did. It only takes a quick touch of the wrong wire (a short) to do a lot of damage or to try to draw to many amps (current) through a device. It's been my way of learning I guess but I learned quickly.

What did I learn?

*Disconnect all power before working.  *Double check my connections and wiring before I start up. And then check again. LOL.  *If I smell burnt, it's broke.  *Voltage and amps (current) are two different things. *You can feed variable amounts of voltage to a dc motor but servos are sensitive to voltage needs. Don't over volt either one.  *Keep DC voltage within all the specs of all devices and servos in the circuit. I include a servo as a device in my understanding. A servo is actually a DC motor that has a control board inside of it. *Devices "draw current (amps) from the power supply (or battery). The power supply does not feed the current. A device or motor will continue to draw amps until it gets what it wants or until the power supply burns up or dies.  *Add up all the peek amps (current) needed by all the devices and motors connected to your power supply. Then get a power supply (or battery) that can deliver at least 25% or more of the current of what is needed at peak draw. *I stopped running power for my motors and servos through the EZB. These things are current hungry as mentioned by others in this thread. When they move or simply run they can quickly rob the EZB of the power it needs to run and cause it to reset. I run all my power around the EZB (unless it's a small device that does not draw too much current). I keep my EZB on it's own independent circuit to the power supply (If you are not using the base then that circuit needs to be fused).    *The WIFI connection needs to be strong and on a channel little used by other's.

I hope this helps a little. Good luck and don't quit.

hi all

i think its best to use all ez robot parts original . can you post a picture of the bad print controller?

I would have a look to see if the reverse polarity protection diode got toasted on the EZ-Bv4 mainboard. It's a small SMD diode near where the voltage comes into the board at the Micro deans connector. I find that if you are really running the EZ-Bv4 hard with tons of current in a DIY scenario this will be the first component to go. If the diode is toast it will have a visible small hole in it. It will usually fail "open circuit". You can either replace the diode or short the diode connections if you aren't worried about reverse voltage hook up. It's an SB540 and can be replaced very easily if you know your way around electronics. If you don't then a local hackerspace or makerspace might have a hot air rework station or soldering iron and the expertise to help you out.

If it was the SWPS chip, those are very hard to come by these days. You could try injecting 3.3V on the ADC power pins as @DJ mentioned, a clever solution since only ~200mA is needed to run the EZ-Bv4 and camera.