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No LEDs lit on 64x64 matrix
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No LEDs lit on 64x64 matrix

by tobobo on Sat Jan 09, 2021 9:26 pm

I have an adafruit 64x64 matrix + Matrix hat with RTC, and after going through the guide I have no pixels lit at all on the matrix. I am a novice with soldering, and I wonder if I somehow messed up the board while doing my initial soldering job—though it appears that all pins are connected and I don't see any obvious shorts.

I'm using raspberry pi os lite on a raspberry pi 400.

I've tried running the matrix demo with options
Code: Select all | TOGGLE FULL SIZE
sudo ./demo -D0 --led-rows=64 --led-cols=64

and
Code: Select all | TOGGLE FULL SIZE
sudo ./demo -D0 --led-rows=64 --led-cols=64 --led-slowdown-gpio=4


to no avail.

I'm wondering if there are some troubleshooting steps I can take before assuming I messed up the matrix HAT. I have a multimeter, but I'm not sure what to be looking for. Does anybody know of some troubleshooting steps I could take, or other ways to diagnose the issue with the display + HAT? thanks!

tobobo
 
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Re: No LEDs lit on 64x64 matrix

by adafruit_support_carter on Mon Jan 11, 2021 12:49 pm

Please post some photos of the HAT showing the soldering job. We can take a look and let you know if that may be the issue. It could still be other things, but that'd be the best first step.

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Re: No LEDs lit on 64x64 matrix

by tobobo on Mon Jan 11, 2021 10:43 pm

Thanks for the response!

As I mentioned, I'm new to soldering, and I can tell just by looking at it that I did a shoddy job at best—I wouldn't be surprised if I need a whole new board. I was certainly struggling but I tried to get it so that there was at least a connection between the pin and the hole—though I certainly can't say the solder points are shiny or smooth. Thanks for taking a look.

IMG_3958.jpeg
IMG_3958.jpeg (185.08 KiB) Viewed 33 times


IMG_3959.jpeg
IMG_3959.jpeg (128.74 KiB) Viewed 33 times


IMG_3960.jpeg
IMG_3960.jpeg (176.93 KiB) Viewed 33 times

tobobo
 
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Joined: Sat Jan 09, 2021 9:07 pm

Re: No LEDs lit on 64x64 matrix

by adafruit_support_carter on Tue Jan 12, 2021 12:27 pm

Thanks for posting the photos. Based on those, some kind of soldering issues seems most likely. In case you haven't found this yet, we have a guide on soldering:
https://learn.adafruit.com/adafruit-gui ... ring/tools

The common problems photos from that guide is a really good reference:
https://learn.adafruit.com/adafruit-gui ... n-problems

It looks like you may have some "insufficient wetting" on a few pins. The amount of solder looks plenty - maybe even a bit much. So initially, don't worrying about adding more solder. Try going back in with your soldering iron and "reflowing" the pins. This just means heating it back up so the solder flows again. But as you do this, pay attention to trying to get heat on both the pin and and the pad. That way the solder will "wet" out onto both when it starts flowing.

Be patient with it. Soldering isn't super tough, but does take some initial "getting used to it". Hope this helps!

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Re: No LEDs lit on 64x64 matrix

by tobobo on Wed Jan 13, 2021 11:07 pm

Thanks for the help! The troubleshooting section was definitely helpful. I took a shot at reflowing the solder pins and here's the result. I think it's looking a bit better.

IMG_3965.jpg
IMG_3965.jpg (156.77 KiB) Viewed 21 times


IMG_3966.jpg
IMG_3966.jpg (106.35 KiB) Viewed 21 times


I tested the pins for the HUB75 connector on the HAT/RTC board, and I thought the voltages I was seeing were a little odd. With the orientation in the photo above, the voltages were as follows (when compared to the ground coming from the LED matrix).

Code: Select all | TOGGLE FULL SIZE
5V 5V 0  0  0  0  0  5V
0  0  0  0  0  0  0  0 


Does this seem normal? I was a bit surprised that any of the pins had 5V (but I'm very new to this as you can tell)

tobobo
 
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Joined: Sat Jan 09, 2021 9:07 pm

Re: No LEDs lit on 64x64 matrix

by adafruit_support_carter on Thu Jan 14, 2021 12:43 pm

That could be OK. The outputs are level shifted to 5V.

Good job on the soldering. It does look much better. I'd say just try the matrix again and see what happens.

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Joined: Tue Nov 29, 2016 2:45 pm

Please be positive and constructive with your questions and comments.