Hello, I’ve connected my servo 2040 with USB detached to the Blow ZI1200 charger (Zasilacz wielozakresowy impulsowy ZI1200 - Produkty - BLOW | Sklep internetowy) set to 4.5V and my servo 2040 burned down.
I first turned the charger on, and then after a few seconds connected the servo 2040 to the charger to prevent the initial spike. The polarity was correct.
No servos were connected to the board.
I don’t understand why it happened - can someone help me understand that?
I can see wires on the EXT connector (external power). Do you have anything connected there?
If so, you have to cut a trace if the external voltage is higher than 5V.
Thank you for the reply,
Yes, my charger was connected there, the USB was disconnected.
So, do I have to cut the trace even if I didn’t connect the USB?
Apparently I made a mistake and I used 9V setting on the charger. But I thought that if I disconnect the usb I’m still good up to 11V :(
If you don’t cut the trace, the voltage of EXT is fed into the LDO. And 9V is just too much. I think the component in your red circle is the LDO (regulator).
If you cut the trace, then the 9V (or up to 11V) is only used for the servos. The Pico always needs 3V3, which is the output of the LDO.
So, do I understand properly, that I have two options:
Is that correct?
Correct. This is also stated in the “Notes” section of the product page (Servo 2040 - 18 Channel Servo Controller). Which I didn’t read before but the schematic tells the same story.
The big question is if you can somehow cheat with this burned board. If you want to try this, this is at your own risk.
The first thing to check if the burned LDO causes some shorts between 3V3, 5V and GND (every combination). If not, you should cut the trace and then you could try to supply clean (!) 3V3 to one of the 3V3 pins. For programming you would need a data-only USB-cable. This is all under the assumption that only the LDO blew up. And there is no guarantee that this actually works.
I probably would not do it, simply because the setup is rather complicated and every time something doesn’t work you wonder if this is because of this setup or not.
Yep, I think it burned enough to trash it :D There is a short circuit between both 5V and GND and 3V3 and GND so I assume the Pico burned as well. And (as you guessed) I’m not electronics expert - if it was only the LDO I could probably re-solder it, but in such case it’s not worth it. I will buy a new servo 2040, but I wanted to first understand what did I do wrong not to burn another one.
Thank you so much for your support!
