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Need help. Identifying components. MIDI-controller repair

Hi, guys! I need help with following. My midi keyboard M-Audio CTRL49 fell off the table while the cable was connected. The connector broke several smd-components on the board (marked D2 and R26). I think but not sure that D2 is some kind of diode array (in package like SOT-363 or similar) which protects the USB. A resistor R26 between 1-3 USB legs might be used to set data transfer rate. How to find out what components should be on the board?

sorry for google translate

board photo
IMG_8361.JPG IMG_8360.JPG IMG_8362.JPG
 

Harald Kapp

Moderator
Moderator
I'm afraid there is only one way 100 % safe: the original schematic (or bill of materials, respectively).

Lacking that:
The interface will work without the protection diodes - at the risk of damaging the interface by an ESD event. You could reconstruct the required pinout of the diode array by following the traces on the PCB and assigning them to the respective pins of the diode array's case. Then find a suitable replacement with the same pinout marketed for USB protection. You'll find lots of them, e.g. here.
The resistor wil be the hard part. If you find a working keyboard, you could measure whats on that PCB and use that value for repairing your keyboard. If you do not have access to a working keyboard (or someone willing to make that measurement for you on his keyboard), then I see no way to find the correct value.
 
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