I have some unusual question: does someone know [![Part1][1]][1] Part2 what kind of electrical part is on that pcb (encircled)? This is a connector board (ME302C) for ASUS MEMO PAD. The part is unfortunately broken, so I cannot see any letters or something else on it. Thank You! Here is a larger picture: enter image description here

  • \$\begingroup\$ Can't tell for sure. Perhaps a better photo would help. It looks like this part. digikey.ca/product-detail/en/toshiba-semiconductor-and-storage/… Could be an opto isolator. Could be anything else too. \$\endgroup\$ – scorpdaddy Jun 28 '16 at 12:19
  • \$\begingroup\$ Closeup photo so we can see how it's connected? \$\endgroup\$ – winny Jun 28 '16 at 12:27
  • \$\begingroup\$ @winny Thanks!! I have made some bigger picture of the pcb. \$\endgroup\$ – Viktor Scherf Jun 28 '16 at 14:31
  • \$\begingroup\$ @Viktor Excellent! Michaels answer below is exactly on target. Just omit the "may" in the first sentence since we now have the pinout/schematic of sorts from your picture. \$\endgroup\$ – winny Jun 28 '16 at 14:33

That part may very well be a common mode choke part for the USB data lines (D+ and D-). The common mode choke would be used to control RF noise and emissions.

It could also be a USB diode clamp device to reduce ESD voltage spikes from the USB connection to reasonable levels.

The reference designator on the board next to the part printed in the white ink may give a clue as to which part type it is. Unfortunately it is covered in blue so it cannot be read.

Here is a typical USB port circuit schematic showing details of both of these types of components in use.

enter image description here

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  • \$\begingroup\$ Thanks a lot! Can I omit the choke when I do not have one now? I would then just solder the contacts. Would it be very bad regarding RF noise? \$\endgroup\$ – Viktor Scherf Jun 28 '16 at 14:30
  • \$\begingroup\$ @Viktor The CM choke is added for EMI compability, either suseptability from external sources, emission from the product itself and/or ESD. If you want to test it, it will most likley run fine without it. \$\endgroup\$ – winny Jun 28 '16 at 14:34
  • \$\begingroup\$ @michael-karas I will do so and report the result! \$\endgroup\$ – Viktor Scherf Jun 28 '16 at 14:45
  • \$\begingroup\$ @Viktor - I think you meant to refer to winny on your comment. But winny is right, you could carefully solder some short pieces of 30 gauge wire across the part pads (in the proper configuration of course) and get your USB port working again. \$\endgroup\$ – Michael Karas Jun 28 '16 at 14:49

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