Asked — Edited

Ez-B V4 Magic Smoke


I bought a DIY kit from Hobbyking. I planned to buy a EZ-Robot kit for a while and for that price, I could not resist any longer. I had my doubts if it was really a genuine kit, but everything looked legit. I build a small two wheeled robot with it to get familiar with ARC etc. I provide power to the EZ-B V4 with a 2s lipo. Everything was working fine, till I tried to power up the EZ-B again today. Because I wanted to put the EZ-B into another robot, I had disconnected all external components. I plugged the lipo in (not fully charged at 7.6V) and at first nothing happened. No lights, no sound. Suddenly I heard a sizzling sound and noticed the well known smell. I immediatly unplugged the lipo. I removed the EZ-B from its shell, plugged it in the power base again and very briefly plugged the lipo in again. The two round components (capacitors?) on the lower board started to release their magic smoke. Is there anything I can do, before I try to contact hobbyking for replacement?

EDIT: I looked at my EZ-B v4 again and at the pictures on hobbykings and your website. While the top board is identical to the pictures, the lower board is different. It has only two capacitors instead of four. Did the lower board also get a upgrade from EZ-B v4 to V4/2? My lower board looks like the one on your EZ-B v4 comms upgrade page.


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Hello @count74,

I apologize for the delayed response, we were on a long weekend here in Canada. If you haven't already worked with Hobby King on a solution please contact our Customer Support. Please send them some pictures as well.

That's correct, the EZ-Bv4 was updated to a v4.1 main board some time ago. The most up to date version is EZ-Bv4.1/2.


Hi Jeremy, thank you for your reply. I opened a RMA with Hobbyking and they already send a replacement. Even more, they send the complete kit again :-). I just saw Hobbyking on your list of retailers, so no need to worry about a counterfeit product. Is there anything i can do to avoid releasing the magic smoke again? My understanding was, that a 2s lipo is fine as a power supply. I did a closer inspection of the lower board and it was the 8-pin IC left of the power connector that smoked (and glowed) not the capacitors. I would like to try and replace the part, could you provide the specs? The writing on top of the IC is not readable anymore.


The chip that was damaged was the switching power supply chip, the RT8299GSP. This chip is pretty robust and has a lot of protection built around it. Usually the only way it can be damaged is by a manufacturing fault. Even with reverse polarity and short circuit protection there have been some very rare events where the chip has been damaged due to these conditions. I would recommend to make sure that you are providing the EZ-B with positive voltage at the barrel plug tip and try not to create a short circuit condition on the Vin or 3.3V power rails.