Shruthi-1 not receiving MIDI (fixed)

Discontinued DIY products Shruthi
#1

Hey all,
This is my first Shruthi. Got the kit with the SMR4. I’ve gone through all the troubleshooting tips in the assembly instructions and everything checks out, except I still get no response from MIDI data being sent to the unit.

And yes, I finally plugged the cable into the IN jack as opposed to the OUT jack. Can rule that one out… >.>

#2

Optocoupler (6N13x)in the right direction ?

#3

Yep, an reading the correct voltages at the correct pins.

#4

Can you confirm a slight voltage Drop on Pin 6 when receiving heavy MIDI Data (use the PitchWhell and bend like hell…) - or better can you scope Pin 6?

#5

No drop on pin 6 at all.

#6

pin 5 continuous with ground? diode correctly oriented?

#7

yes and yes.

#8

No drop and pin 5 to GND correctly means the OpAmp isnt working… can you swap to prove?

#9

sadly, no… all the optocouplers I have access to are surface-mounted in other equipment.

#10

Tried another midi cable?

#11

A brand new MIDI cable tried. Still nothing. Ordered a stash of optocouplers from Mouser.

#12

Correct resistors around the optocoupler? too big a value and the LED won’t light enough inside the optocoupler.

#13

using what came with the kit shrugs

#14

After receiving a new batch of optocouplers and it still not working, I took a closer look at the resistors again and found that the brown and red had messed with my colourblindness and I had swapped the resistos for R18-19 with the resistors for R1 and 14. quick swap, and it works wonderfully. \\o/