# Serial pins, and PC USB port damaged using a USB to Serial converter (PL2303HX)

I am working in a project for getting data from a Load Cell, in the project I use a very good Shield built by a very good friend, this shield has a PGA (Programable Gain Amplifier), a Fast ADC chip, and a voltage regulator (to get 5.0 +/- 0.1 V). This shield is over an Arduino Uno, and when I get a command from Serial port I start getting and printing the time and the load cell voltage data each 1 ms, and this is working pretty nice!.

The Arduino is powered by a 120 AC to 5VDC adapter (see the photo attached), this 5 VDC are elevated to ~8 VDC by a

this was because of I wasn't able to get a 120 AC to 8 VDC adapter, and these 8 VDC (I need 8 volts for the 5.0 V regulator mentioned above) are plugged into the jack power conector of the Arduino Uno,

The data from the serial port goes to a USB to Serial Rs232 cable converter, this use a PL2303HX chip (look the link down), and this is conected to the pc with a 3 m USB extension

https://www.amazon.com/Armorview-PL2303HX-Cable-Module-Converter/dp/B008AGDTA4

The problem is that this is the second time that I heard something like an electric short and all the things conected to the Serial port is damaged, I mean the PC USB port, the Serial to USB cable Converter, the Arduino (once) and the Arduino serial port (in the other time).

Looking for what happened I opened the USB to Serial Cable and I saw something like a fingerprint of a spark (see the photos attached), and how you can see this happened in the power line. According to this I guess that this was an overvoltage or an overcurrent in the PC usb port, but the other things like mouse and keyboard didn't fail.

I was wondering if someone could help me to understand what happened, I appreciate any idea.

thanks Thanks for your answers, @Ali_Chen this is a block diagram of my circuit

I don't need exactly 8 volts, but I need 7 V or more for the power jack to power the Arduino, so I choose 8 volts, I use the booster because I couldn't find more than 5V or 12V adapters, and with the 12V regulator of the arduino gets pretty hot, so I prefer to use the booster.

@Ali Chen I saw that too, that the damage was in the power lines, and for that reason I guess that was an over voltage or over current from the pc USB port, but do you think that too?

@slightlynybbled, I had purchase a better supplier USB-TTL cable from SEED, but I buy it from Digikey,

https://www.digikey.com/product-detail/en/seeed-technology-co-ltd/321010012/321010012-ND/5487751

I know this is not as good as Adafruit once, but I am in Colombia and it is really difficult to get this things because I have to pay for shipment and some taxes when it get into the country

• Please explain why do you need the 8 V supply, and how do you apply it to your setup. Schematics in a block form will help. – Ale..chenski Oct 27 '17 at 0:00
• Other peripherals on different ports didn't fail because computer has over-current protection and shuts the USB port down so that it does not damage the controller. I think somewhere your power rails were short and therefore the tragedy. – ammar.cma Oct 27 '17 at 2:47

Try the same thing with something more trusted. Adafruit is well-trusted with the community, try one of theirs. Yes, I realize that it is $18 instead of$7, but isn't that worth your USB port, arduino, and other hardware?