geekhack

geekhack Projects => Making Stuff Together! => Topic started by: GreenFortGriot on Tue, 08 October 2019, 08:00:46

Title: Help fixing power of a PCB (Akai Mpk249 midi Keyboard)
Post by: GreenFortGriot on Tue, 08 October 2019, 08:00:46

The usb port 2.0 type B female connector used to power the midi keyboard broke off the PCB Board. i soldered a new connector onto the pcb board. When i try to power on my Midi keyboard, I get this message.

[attachimg=1]

The problem is not the usb ports on my MacBook. When i plug in other usb devices they work. The model of the PCB board is a AKAI TWPC13A00901. Here is a photo of the board (stock photo).

[attachimg=2]

This second zoomed in photo displays a blue square shows the power button. the red square that shows the usb connector. The model of the USB connector is a USB Port 2.0 Connector Type-B Female. It has 4 pins & 2 anchors. That is the problem area.

[attachimg=3]

I removed the usb connector that i recently soldered on to figure out the problem. With information i gathered these are the issues. The top and bottom hole on the right seem to be cracked. there are no more solder pads. multiple torn runs. I colored in the trace areas around where the connector is supposed to go. That seems to to be another problem area. I need additional assistance. Thank you.

[attachimg=4][attachimg=5][attachimg=6][attachimg=7]

Title: Re: Help fixing power of a PCB (Akai Mpk249 midi Keyboard)
Post by: suicidal_orange on Tue, 08 October 2019, 19:09:52

Interesting first post, this forum is usually about typing keyboards not musical ones :))

Luckily USB is USB and bad soldering is bad soldering (no offense) so let's have a look.  First thing to check - does the cable fit the same way up in your new connector as the original?  If the pins were swapped that's one good way of confusing a computer, though 'too much power' suggests a short between ground and 5v probably because the holes cracked through.  From here on I'm assuming the connector is the same as the original.

It looks like the trace from R32 is still attached to the via (hole) next to the 6 of the R136 label, if it is you can solder a wire between the top left pin of the connector and the right side of R32 (your red line) and it won't know any difference.

Same with your blue line - if the via above the right of D8 is still attached to it's right leg solder a wire from the pin to the leg and all good.

Your turquoise and orange lines are actually gaps between traces, the thick one in the middle (your yellow line) is the trace, it's thicker than the two above because it's the power line while the others are for data.  There is no good picture but it looks to be heading towards the end of the yellow capacitor - hopefully you can see with the board in your hand.  If in doubt try and get a picture with it in focus, if you're sure - you guessed it - solder a wire between the pin and the chip.

The last pin is ground so it connects pretty much everywhere.  Your green line to C70 should work, if you want to be really sure look up the pinout for the chip the other side of C70 to check its top right pin is ground.  I would have but I can't make out the writing...

One last thing - when I say 'solder' you might like to get someone else to do it, soldering to small factory soldered components can be tricky and looking at the damage you've done you (or maybe your soldering iron) might not be up to it.

Good luck!

Title: Re: Help fixing power of a PCB (Akai Mpk249 midi Keyboard)
Post by: praxis87 on Sun, 20 October 2019, 19:20:14

While it looks pretty bad, assuming you didn't fry any of the other components on the board, it shouldn't be too bad to fix.  You just need to physically attach your replacement connector to the board (probably with glue at this point) and run jumpers for vbus, gnd, d+, and d-.  I agree with suicidal_orange on suggesting you get some help with that.  Some computer repair shops will do soldering for a reasonable fee.