Electronics > Beginners
Pulling my hair out. Circuit boards stop working once shipped to client and more
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Jackster:

--- Quote from: free_electron on July 01, 2019, 05:18:59 pm ---a couple of other things ( apart from the fouled up pcb spacing )

- not enough bulk capacitance in the design
- not enough local capacitance in design
- the crystal you use is a resonator. your processor fuse bits may need to be tuned for that ! check what the load capacitance and bleed resistor is in those things. you can buy those in different variants and the tuning needs to be done.
- aluminum case.... do you connect that electrically to your system ground ?

--- End quote ---

I have copied the Arduino Nano circuit. Is there design wrong or am I not placing the caps in the correct place?

The case is anodised so is not conductive. So no I do not. Should I?
free_electron:
Arduino is not exactly a case of 'proper' design. They take too many shortcuts.
That aside , what else is on your board. Anything drawing pulsed currents like muxed displays , rf transmitters etc ?
Jackster:

--- Quote from: free_electron on July 01, 2019, 06:49:48 pm ---Arduino is not exactly a case of 'proper' design. They take too many shortcuts.
That aside , what else is on your board. Anything drawing pulsed currents like muxed displays , rf transmitters etc ?

--- End quote ---

Yea I have 4-8 seven segments displays and a nrf24l01.
Psi:

--- Quote from: free_electron on July 01, 2019, 06:49:48 pm ---Arduino is not exactly a case of 'proper' design. They take too many shortcuts.
That aside , what else is on your board. Anything drawing pulsed currents like muxed displays , rf transmitters etc ?

--- End quote ---

The main problem with using arduino in a professional product is obscure bugs in the libraries.
They are written by random people who may not be very good at it.
OwO:

--- Quote from: Jackster on July 01, 2019, 04:03:44 pm ---The green PCB is correct. The Black one is one from the bad batch from PCBway.
The spacing between the holes is 1.27mm and the distance between the solder pads should be 0.375mm.

--- End quote ---

Check what the annular ring width is. It's possible their software enlarged the pads because the annular ring spec was violated.

If it took this long to triage a fault in production as simple as some shorted pins, then I would say the process needs some work too and not just the design. Were these first few boards soldered manually or did you put the whole batch to automated assembly? The contractor I use always assembles one board from each batch by hand as a sanity check before starting any automated assembly.
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