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Doing some repair work on a Yamaha FGDP-30 finger drumming instrument, and I came across this unpopulated footprint on the main PCB

pcb image with unpopulated footprint

The CN999 label and proximity to the main IC lead me to believe it may be some kind of debugging or programming port. It's a bit larger than the Micro USB footprint found elsewhere on the board, but I'm not discounting the possibility it is also a USB footprint of some kind. I'd just love to be able to toss a header on and see what it can be used for!

Additional Info: Per the comments/responses, here are a few more clues:

  • The pin pitch seems to be 1.25/1.27mm
  • The IC its connected to isn't well documented, its a SWX03S from Yamaha, which seems to maybe be a Renesas platform
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    \$\begingroup\$ It it some manner of standard straight terminal header like something from JST, pitch looks about 2mm but always hard to tell from pictures. Measure the pitch with calipers. As for what it is used for, nobody can guess that without any context or documentation. \$\endgroup\$
    – Lundin
    Feb 21 at 7:16
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    \$\begingroup\$ You are probably correct in identifying it as a debugging port. Call me a pessimist, but it seems like a fairly convenient way to brick your device rather than do anything useful or cool with it. \$\endgroup\$
    – vir
    Feb 21 at 7:18
  • \$\begingroup\$ A photo of the IC might perhaps reveal what kind of programming interface it uses. Like standard SWD for Cortex M, which would fit into a 5 pin custom connector. Likely this is some SoC thing but maybe with an ARM core on board. \$\endgroup\$
    – Lundin
    Feb 21 at 7:22
  • \$\begingroup\$ The pitch seems to be 1.27mm based on a nearby SOIC16 flash that seems to have identical pitch (waiting for new batteries for my calipers). The IC is a Yamaha branded SWX03S which I suspect is a Renesas arch chip. Added those details to the original post! \$\endgroup\$
    – Nick Badal
    Feb 23 at 16:42

2 Answers 2

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Some kind of surface mount vertical receptacle, probably a debugging port. Something like this (depending on pitch size, could be an SH model, or other):

https://www.digikey.com/en/products/detail/jst-sales-america-inc./B5B-PH-SM4-TB/926834

B5B-PH-SM4-TB

I suggest not trying to interact with it, as it's highly unlikely to not brick your board, as other comments have said.

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  • \$\begingroup\$ I think you've nailed it! GH series was the right match for the pin pitch, will mark as solved once I can compare the part in person shortly! \$\endgroup\$
    – Nick Badal
    Feb 23 at 17:16
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The JST series was the clue I needed to find the GH line and compare the footprints and find the header on Digikey

Will mark their answer as the solution once the parts arrive and I can confirm its an exact match!

seemingly matching jst gh footprint

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