Digital Board recommendation

The 4 holes on the outside edge on the midi socket should be plated through holes connected to gnd, right now they are just holes. Those pins serve as strain relief for the midi connector and there are also shielded midi connectors that have those connected to a metal shield. Not being able to solder them down will put a fair amount of strain on the solder joints of the midi connector pins when connecting and disconnecting… I just scraped off the solder mask and soldered mine down to the gnd plane.

There is also a midi connector on the market that has a bigger footprint than the usual ones and will interfere with the opto and related components (only significant for self sourcers like me I guess)

I know about this problem, and this is a compromise I had to make to support a specific “feature” of the Shruthi-1: the schematics can be edited/modified with the freeware version of Eagle.

@altitude: I suppose you want to solder them and not glue them in case of substitution, am I right?

@muldee I just scraped away the solder mask and soldered them to the ground plane (easy fix) I dont know how well gluing them would work. Without those pins secured, when you plug and unplug a midi cable, you will be pushing/pulling on the pins soldered to the board . Something to consider since it will likely fail at some point. I cant even count the number of times I have repaired this or that socket since it was not properly mechanically fastened and broke a solder joint or lifted a trace off the board

@pichenettes: Elaborate?

@altitude: Eagle has a limit on the rectangular area on which you can place parts on your PCB. If this exceeds a certain area, the software must be registered. I own an Eagle licence but I want to make it possible for people to open and edit the board file, so I stick to the “freeware zone”.

However, now that you have told about scratching the solder mask, I think I can “simulate” what you did without putting a pad - if I directly draw a circle on the Bottom stop layer (which decides what the solder mask covers and what it doesn’t). Basically, the same trick as the one I use to have the श्रुति logo on the board.

Sure, just a pad within the area that you can bend and solder the leads to would work fine…

oh dear, i was wondering about those four holes there, too, but ignored them since there was nothing there to solder those pins to.

so i just could have scraped away some of that black surface of the pcb around those holes instead?

i wish i had known this before soldering in the lcd - now it covers those holes and i’m not sure i’m up to unsoldering it again right now. although i guess i will have to at some point to prevent the midi sockets from coming lose…

Well, I was worried of the “weakness” of midi ports but I’ve assembled the shruthi anyway… then I changed my mind and I have glued the four edge holes with a very small drop of epoxy bi-component sealant. Now midi ports are well anchored.

This can be a good solution for those who have already mounted the Lcd.

The altitude method is the best (of course) because it let the midi ports to be unmountable if required.

Here is a pic of how I secured mine:

@altitude: here’s how I modified the PCB (big rounded zone of copper exposed around the holes).

ok, so this will be control board v0.6? when will it go into production? the next run of kits which we are currently waiting for will still be the old version, right?

The v0.6 of the board will probably be ready for the december batch. I had one prototype done but there are other things I want to fix in it (including this MIDI connectors thing) and that did not make it into the first proto. Here is a summary of the changes:

  • Silkscreen correction for the 10k resistor
  • Improved routing, changed the position of some bypass caps
  • The ISP connector is now oriented on the top of the board, so you only have to remove the top cover to hack an already assembled unit
  • Shift register output. Use it to drive extra LEDs in your case, digital switches on the filter board (:wink:) or a mysterious device fcd72 is working on
  • GND / +5V connectors at a few strategic places
  • The middle holes have been removed - I think the assembly is quite robust already with 4 spacers

Yeah! Its definitely mysterious!

(edited) Oh, I forgot its also a bit of magic in it… heres a brief glimpse of the half finished heart of the Proto:

1000 thanks to Olivier for including my suggestions into firmware 0.92 and board revision 0.6 to make the mess above work (hopefully)! The last time i had that much fun it was probablly illegal…

come on, what is it ???

You’ll love it!