gm5x5x5 midi in 4 not working

Testing/Troubleshooting
1

High,

Yesterday I finished my gm5x5x5 project from last bulkorder, Version 1.1.

Everything seems to work fine except for my forth midi input. If I put a signal in witch works on the other inputs, it’s not working on input 4, no flashing LED’s nor midi input in my software. I checked everything, changed both corresponding IC’s, still nothing. Anybody any idea?!

Greetings,

Roel

2

first i would check the optocoupler…in my last order of 10 pcs. i got 3 broken ones…so maybe that one is dead…just swap it with a working one and check again.

3

Check the soldering of the pin 21 on GM5 chip too

4

Thanks for the answers.

I swept the optocopler with a working one with no result.

I measured pin 21 (counter clockwise from the spot) and soldering seems OK.

But thanks anyway!