Shruthi XT MIDI borked

so it looks like i fried something while testing my freshly built XT. did everything as in the guide, but did not assamble the box before testing. i sandwitched the two boards and didn’t realize, that the 7905 and 7805 heat sink metals touch the XT motherboard. in the case of the 7805, it’s not that serious, as the heatsink is just GND, but the 7905 heatsink is the same as the INPUT pin. this unfortunately touched the optocoupler at pin 7.

when i powered it up, the screen went up, but none of the controls worked. so i disconnected it and assambled it in the box, after another power up everything seemed to work. everything apart from MIDI in that is :C

just ordered a couple of optocouplers, let’s hope it’s just that and not the RX pin of the MCU…

maybe a warning in the assembly docs about sandwiching the bare boards without spacers would be a good idea?

so no victory candy for me : |

The MCU isn’t that expensive either.

A “don’t do this” guide would be never ending. At the end of the day when people do something stupid they learn something. The fear of not doing something stupid again instils a more careful approach to DIY. Checking and double checking.

The controls not working doesn’t really sound like the optocoupler, more like a 165 died. Not sure about the XT specifics but on the regular Shruthis that’s the usual victim of inter board shorts.

the controls work fine, it was just for the first power up, i guess it grounded some pins of the 165. after putting it into the box, the controls worked, i could also get sounds from it via the “let’s jam” thing with some sequences. all pots and switches work. i could try out everything. only when i connected it to my laptop via midi it didn’t receive any messages. also the optocoupler feels a little warmer than the other chips.

165 are cheap, Hypnotoad says: “buy them in tens”

replaced the 6N137 and my midi works now, yaay victory candy