I have an old desktop pc (2005), for teaching I was carrying out measurements with the multimeter in one of the two front USB ports, but with the test lead I think I made a short circuit between the 5v pin and the gnd (usb frame); I smelled the smell of burning.
Analyzing the small Nec front card (it has two USB and audio connections), and looking closely at the path of the two USB 5v (from pin 1 of the port to the red cable that will go to the MB), I see that we have in each track: a capacitor in parallel (both measure about 10nF, they seem ok to me), and then we have a resistance in series (R8 on the left and R7 on the right); without unsoldering them, I measure 1.2Kohm on the left one and 0.2ohm on the right one. At pin 1 of the two ports ok I still get the 5v.
But having smelled the smell of burning on that card, something must be broken: visually I thought it was the R on the left, while the right one looks better. But by measuring the continuity on the left I do not have (in fact the R8 is 1.2Kohm), while on the right if I try the continuity on R7 I hear the beep ... and in fact I only have 0.5ohm.
In your experience, how much should the value of these resistors be and therefore which of the two should be ok and which fault? They didn't screen print anything on the body ..
Thank you
Charlotte