Meter board with control backpack *updated*

Finished soldering the control backpack last night, but I haven't had a chance to fire it up and test yet.  I am certain there will be problems, but an initial continuity check with a meter shows all traces to be doing what they're supposed to do.

Here's the final front and back layouts for the control board:

Top and bottom layers, as I print them for toner transfer.

It's got two TPIC6B595 shift registers with built-in darlington to sink the 11 rows of LEDs, one 74HC595 shift register that's driving 7 high-side PNP transistors to push the 3.3v up each column, and resistors for the LEDs and the transistor bases.   On one side is 11 pin headers to plug into the columns of the meters board, and on the bottom are 7 header pins for the rows.

Even through there's only 3 control wires and VCC/GND, I used a 5x2 header block to interface with the offboard microprocessor because 5x2 is the easiest ribbon cable connector to find around here, and I figure it's easiest for all of the submodules to use the same connector.  Maybe this is dumb, I'll find out eventually :)

Finally, here's a shot of this board plugged into the meters board.   I haven't cut the boards down to their final size or cleaned them up yet, that would be wasted time if the thing is broke.

I had to stand the 7-pin headerblock off the board by a few mm to get the iron in underneath.  Only afterward did I realize I could solder the headerpins 'upside down' and then just push the plastic retainer down against the board.   Live and learn.

The biggest lesson I've learned in this stage is that etching your own board is easy, but soldering to your home-etched boards can be a major pain in the ass.  Specifically, since there's no through-hole plating, you can't just solder your through-hole components on either side and be done;  you have to solder on the side where the pad connects to the trace.  If this is the same side as the component, you're stuck trying to work the soldering iron in underneath the component.   This can be really difficult, and fixing mistakes becomes even more difficult.

I will need to keep this in mind as I lay out future boards, as I really did not enjoy doing this at all and it made for a sloppy solder job.  If I can't get it right in layout perhaps I will add pads right before the component pads and solder to that, then use a wire to jump to the other side.

*update*
shit's broke,   Feels like a solder bridge somewhere, though it's of course entirely possible the whole layout is wrong.   Losing is Fun!