PreenFM > preenfm2 and preenfm3

resisitor network orientation?

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benjaminr:
Hello!
My name is Ben, very excited about this synth! I've built a few little synths and things before (atmega and teensy based mostly), but this is my first ever PCB build!

My question is: which holes on the PCB correspond to the common grounds for the resistor networks?

I'm just troubleshooting/diagnosing and am not confident in my initial assumption that the square holes are ground (I used 16 10k resistors and just made my own networks, so it's not as simple as lining up the arrows). From looking at different sources it seems like sometimes these networks' common terminal is on pin 1 and sometimes on pin 9?) My local shop doesn't stock 9 pin networks so I bought a couple 11 pins today and trimmed off two of the leads, so I'll probably plop though in instead of messing around with all the extra solder points.
 
Not sure if this is where my issue is (blank screen, 3 solid leds), but I want to be sure I've got it right before moving forward with diagnostics. Lol I'll likely have another question or two if I can't get it figured out.

Thanks so much Xavier for your work on this project, it sounds like a terrific synth and I'm very excited to get to playing with it! :D :D :D

(edits: spelling)

Xavier:

Hi Ben,

16 10k resistors to replace the network, nice   ;)

Do you have the building doc ?
http://ixox.fr/preenfm2/build-it/thebuild/
Search for "network" and you'll see the network resitor picture in place.

But i don't think a problem with the network can lead to a blank screen.
Don't hesitate with your questions, that's what this forum is for.

Xavier

benjaminr:
Hey, thanks for the reply!
Yeah, I followed the build doc for the whole assembly, but for the part with the resistor networks it just shows the networks being placed according to the dot on pin 1. I just wanted to confirm that the square through hole is indeed the ground pin/common terminal for the network (I'm like 90% sure it is, but on the website for the resistor networks I bought yesterday it says the last pin is the ground so I'm just not confident.
I'm at work now so sorry if I'm slow to respond!

Xavier:

--- Quote from: benjaminr on January 04, 2019, 12:26:10 AM ---I just wanted to confirm that the square through hole is indeed the ground pin/common terminal for the network

--- End quote ---

OK i see. Yes it is !

You can easily check with a multimetre how your network is built.
10 K ohm between the common pin and any other one.
20 K ohm between any of other pins.

benjaminr:
Awesome! Yeah I had the networks themselves figured out was just tripping about the orientation in the PCB. Looks like I had then right in the first place lol. (Square solder pad always means ground, right?) Thanks so much for the replies! Gonna reflow all my connections tonight and check my component values and then I'll probably have more questions! :)
 I'm in Vancouver, Canada so it's currently 630 am for me

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