(tr)uSDX Forum

hi , yesterday i assembled (tr)usdx it was right with usb power, this morning i connected it to a battery 12V and c2 capacitor near the power connector fired (it was strange becouse after i connected +pole, capacitor fired when i touched the other faston to connect at -pole before to connect it, (tr)usdx was on the table not in my hand), i disconnected all, i changed the capacitor 10mF 25V i wanted to test if all was right and i connected usdx by usb but the c41 capacitor (same value of C2) near usb connector fired. What I must do? Help me please

The only way that could happen would be with reversed tantalum caps. They act as a big fat short circuit when soldered in reversed.
Please share a detailed picture of your mainboard.

73 Manuel; DL2MAN

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C41 looks installed reversed on your PCB.... And that´s probally the root cause of your problems.
Look at my pic of a working mainboard for comparison. Watch especially for the markings on the tantalums: 73 Manuel; DL2MAN

i tested the radio with usb power and it was ok before i connect battery, it is possible? do you think i can resolve soldering 2 new capacitors? can i use normal capacitors (no smd) 10uF25V? same value but of this

Yes, you can use them, and yes, it is possible.

73 Manuel; DL2MAN

Hi Manuel, two capacitors are soldered, the radio is ok powered by usp port, but now i am afraid to connect the radio by battery pack
what is the best value (Volt, Ampere) of power supply?
I'm eager to try the radio with the antenna...
73 Peppe: IU8QGZ

You need 13V 0,6A.
Anything between 10 and 14V is ok, anything more than 0,6A is ok.
Power supply like for most other rigs is perfect (13V 20A for example)…

thank you very much Manuel
i will put the (tr)usdx between two plexiglass panels becouse i want to see all components...I like it

73 Peppe: IU8QGZ

Tantalum electrolytic and aluminum electrolytic capacitors when connected backwards will usually work for a while if you are operating on low voltages relative to the rated voltage of the caps. That's probably why it worked on the 5 Volt USB supply. But once you hit it with 12 Volts the dielectric layer couldn't handle it and they shorted out.

thanks